Hydraguide HGF Series Hydrostatic Steering System 318, 322, 330, 332, 420, 430 Parker Service (SM2753) 318 322 330 332 420 Service(SM2753)

User Manual: 318, 322, 330, 332, 420, 430 Parker Hydrostatic Steering System - HGF Series Service (SM2753) WFMFiles.com

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Hydraulics

Hydraguide™
Hydrostatic Steering System
HGF Series Service Procedure
Service Manual 2753

Hydraulic Pump/Motor Division

HGF Design Features Illustration

Port Cover
Port Manifold

Isolation Manifold
Metering Ring
Rotor Set
Upper Cover Plate

Hex Drive Assembly
Valve Springs
Valve Set

Drive Link
Commutator Set
Drive Plate
Thrust Bearing

Upper Cover & Jacket
Tube Assembly Set

Input Shaft/Wheel Tube

Hydraguide™
HGF Design Features

The model HGF Hydraguide™ power steering unit is Ross' most recent addition to its series of hydrostatic
steering products. The HGF combines several advanced features designed to meet industry's needs for improved
steering of its construction, industrial, and agricultural vehicles.
• An ultra compact and light weight package designed for easy installation with fluid connections at the lower end of
unit.
• An open center fast response rotary plate type valve (spring centered) with options of open or closed cylinder ports
and "power beyond".
• Small eccentric rotor set provides smooth operation.
• Lower optional noise levels.
• Column (jacket tube) and input shaft/wheel tube integral to unit for improved column/unit alignment. Lengths tailored
to user requirements.
For operation, the HGF system requires the following components:
• an engine-driven pump,
• a relief valve,
• a cylinder or cylinders,
• a reservoir and filter,
• suitable fluid lines or hoses, and
• the HGF hydrostatic unit.
The driver has power steering control at all times, so long as system components work together, system integrity
is maintained, and adequate fluid is present. If there is a failure in the high-pressure circuit, a loss of power steering
will result. The HGF, however, is designed to have some manual steering capability, depending on the installation. If
you can't manually steer the vehicle without using extraordinary measures, such as leaving your seat, or pushing with
your legs, don't try it. Some vehicles may be impossible to steer manually because of their weight and size. Repair
the failure in the power circuit.
WARNING: SUCH EXTRAORDINARY MEASURES SHOULD NOT BE USED IN ATTEMPTING TO MANUALLY
STEER THE VEHICLE, AS THEY MAY GENERATE FORCES IN EXCESS OF 125 FT. LBS. (169 N m),
THEREBY DAMAGING THE UNIT INTERNALLY, WHICH COULD RESULT IN A COMPLETE LOSS OF
STEERING.

Table of Contents
Page

Definitions .....................................................................................................................................................1
Introduction ...................................................................................................................................................2
Design and Operation...................................................................................................................................3
HGF Hydraguide Steering System .............................................................................................................. 4
Troubleshooting Guide................................................................................................................................. 5
Troubleshooting Checklists ...........................................................................................................................6
Component Alignment Groove Illustration (Fold-Out) ................................................................................7B
Exploded View (Fold-Out) ......................................................................................................................... 7C
Tools and Material Required for Servicing ....................................................................................................8
Torque Chart.................................................................................................................................................8
Disassembly and Inspection .........................................................................................................................9
Assembly ....................................................................................................................................................21
Hydraulic Fluid ........................................................................................................................................... 36
Filling and Air Bleeding the System ............................................................................................................36
Tips for Maintaining the System ................................................................................................................ 37
Warnings for Proper Steering System Operation .......................................................................................37

WARNING: ALL STEERING MECHANISMS ARE LIFE AND LIMB ITEMS. AS SUCH, IT IS
IMPERATIVE THAT THE INSTRUCTIONS IN THIS BOOKLET ARE FOLLOWED TO THE LETTER.
FAILURE TO OBSERVE THE PROCEDURES SET OUT IN THIS PAMPHLET MAY RESULT IN LOSS
OF STEERING.

ii HGF Series Service Procedure

Definitions
NOTE:

A NOTE provides key infor mation to make a procedure easier or quicker to
complete.

CAUTION:

A CAUTION refers to procedures that must be followed to avoid damaging the HGF
or other system components.

WARNING:

A WARNING REFERS TO PROCEDURES THAT MUST BE FOLLOWED FOR THE
SAFETY OF THE VEHICLE DRIVER AND THE PERSON INSPECTING OR
REPAIRING THE HGF.

Disclaimer
This Service Manual has been prepared by Ross for reference and use by mechanics who have been trained to repair
and service steering components and systems on commercial and non-commercial vehicles. Ross has exercised
reasonable care and diligence to present accurate, clear and complete information and instructions regarding the
techniques and tools required for maintaining, repairing and servicing the complete line of Ross HGF "Hydraguide"
Hydrostatic Steering Units. However, despite the care and effort taken in preparing this general Service Manual, Ross
makes no warranties that (a) the Service Manual or any explanations, illustrations, information, techniques or tools
described herein are either accurate, complete or correct as applied to a specific HGF steering unit, or (b) any repairs
or service of a particular HGF steering unit will result in a properly functioning steering unit.
If inspection or testing reveals evidence of abnormal wear or damage to the HGF steering unit or if you encounter
circumstances not covered in the Manual, STOP–CONSULT THE VEHICLE MANUFACTURER'S SERVICE MANUAL AND
WARRANTY. DO NOT TRY TO REPAIR OR SERVICE AN HGF STEERING UNIT WHICH HAS BEEN DAMAGED OR
INCLUDES ANY PART THAT SHOWS EXCESSIVE WEAR UNLESS THE DAMAGED AND WORN PARTS ARE
REPLACED WITH ORIGINAL EQUIPMENT REPLACEMENT AND SERVICE PARTS AND THE UNIT IS RESTORED TO
ORIGINAL EQUIPMENT SPECIFICATIONS FOR THE HGF STEERING UNIT.
It is the responsibility of the mechanic performing the maintenance, repairs or service on a particular HGF steering
unit to (a) inspect the steering unit for abnormal wear and damage, (b) choose a repair procedure which will not
endanger his/her safety, the safety of others, the vehicle, or the safe operation of the vehicle, and (c) fully inspect and
test the HGF steering unit and the vehicle steering system to insure that the repair or service of the steering unit has
been properly performed and that the steering unit and system will function properly.

HGF Series Service Procedure

Introduction
Service Manual for Model HGF
This service manual has one purpose: to guide you in maintaining, troubleshooting, and servicing the HGF
Hydraguide power steering valve.
Material in this manual is organized so you can work on the HGF and get results without wasting time or being
confused. To get these results, you should read this entire manual before you being any work on the HGF.
The next section of this manual, Design and Operation, treats the major parts of the HGF and explains how they
function together. The knowledge you acquire from reviewing this section should assist you in solving your steering
problem.
This manual also contains troubleshooting information and checklists. With them, you can diagnose a steering
problem without removing the HGF from the vehicle. If you must service the HGF, the checklists will help you to
determine where the problem may be.
The three-column format of the Disassembly and Inspection, and Assembly sections will make it easier for you to
service the HGF. Column 1 gives a brief key for each procedure. Column 2 explains in detail the procedure you
should follow. Column 3 illustrates this procedure with photographs. Pay special attention to the notes, cautions, and
warnings.
A fold-out page with an HGF Hydraguide exploded assembly view is provided in this manual. The component part
names and item numbers assigned on this exploded assembly view correspond with names and item numbers (in
parentheses) used in the disassembly and assembly procedures set forth in this manual. When this exploded
assembly view page is folded out, you can easily identify components and locate their relative position on the
exploded assembly view as you follow the disassembly and assembly procedures.
As you gain experience in servicing the HGF, you may find that some information in this manual could be clearer or
more complete. If so, let us know about it. Don't try to second guess the manual; if you are stuck, contact us.
Servicing the HGF should be a safe and productive procedure, in order for the unit to deliver the reliable, long-life
operation engineered into it.

HGF Series Service Procedure

HGF: Design and Operation
(See HGF Design Features and Design Illustration)

Satisfactory performance of the overall hydraulic system
requires a well-engineered installation. The hydraulics
must meet the design features of the vehicle and
contribute to the operation for which the vehicle was built.
Make no changes to the steering system without first
consulting qualified factory service personnel. Ross
Gear extends engineering advice and welcomes
requests for assistance.
Engineering contacts can provide information on such
hydraulic components as pumps, cylinders, and fluid
lines. The HGF control unit works best with a balancedarea cylinder design.
HGF: Design
The HGF Hydraguide unit consists of a fluid control valve
section and a fluid metering section. These are
hydraulically and mechanically interconnected inside the
unit.
Control Valve Section: Operation
The HGF Hydraguide uses a servo-reactive (feedback
control) valve which is centered by two sets of three coil
springs. The valve regulates pressure and directs pump
flow to the steering cylinder or cylinders. The valve is of
the open-center type: when in the neutral position, it
allows fluid to flow from the pump to the pressure port,
through the HGF unit to the return port, and back to the
reservoir.
The valve is available in open- or closed-cylinder

configurations, each of which brings its own advantages
to bear in the hydraulic system.
Open Cylinder: cylinder ports are open to the metering
pump, allowing road or ground reaction to rotate and
recenter the valve, as the vehicle's steering geometry
provides recentering forces. When the driver completes
a turn, the steering will recenter, as happens, for
example, in most automobile power steering systems.
Closed Cylinder: cylinder ports are blocked to the
metering pump, preventing road or ground reaction from
rotating and recentering the valve. The driver must steer
to "straight ahead" or another position. This design is
useful in a vehicle which must remain turned while the
driver takes his hands off the steering wheel to operate
other controls.
Metering Section: Operation
The metering section performs three functions:
• It meters (measures) fluid to the cylinder or cylinders:
• It maintains the ratio of hand wheel turns to the
direction of the steered wheels; and
• It acts as a pump for manual steering in the event highpressure fluid does not reach the HGF unit.

HGF Series Service Procedure

HGF Hydraguide™ Steering system

Return
Pressure

OPEN CENTER
HYDRAGUIDE™ STEERING

HGF Series Service Procedure

POWER BEYOND
HYDRAGUIDE™ STEERING

Troubleshooting Guide
NOTE:

Before troubleshooting a steering problem, check service literature published by the
vehicle and component manufacturers. Follow their instructions, if given, for
checking any component but the HGF Hydraguide unit.

Preparation
Make your troubleshooting easier by preparing as
follows:
• work in a clean, well-lighted place;
• have proper tools and materials nearby:
• have a space set aside where you can lay components,
parts, and tools; and
• have an adequate supply of clean petroleum-based
solvent.
WARNING: SINCE THEY ARE FLAMMABLE, BE
EXTREMELY CAREFUL WHEN USING ANY SOLVENT.
EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE
INJURY OR DEATH.
WARNING: WEAR EYE PROTECTION AND BE SURE
TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR
PRESSURE REQUIREMENTS.
Preliminary Checks
For all their complexity, hydraulic systems are often
trouble-free. The steering problem an operator
complains of could be caused by something other than
the hydraulic components.
Thus, once you have determined the problem and test
driven the vehicle (if possible), start with the easy-tocheck items.
On some vehicles, the conditions of the tires, especially
on the steered wheels, may affect steering. Make sure
pressures are at manufacturer's specifications. Make
sure tires are balanced and that they show no signs or
damage or severe wear. Check that they are mounted
properly.
Check steering and front end linkage. Broken, loose, or
binding parts could cause certain steering problems.

See if something in the steering column is loose or
binding.
If belts are present, check all of them. A tight belt could
also be glazed and a slipping belt doesn't always squeal.
In addition, the following could also contribute to a
steering problem:
• an overloaded vehicle;
• parts damaged from impact not properly repaired, or
that should have been replaced; and
• improper replacement parts.
Hydraulic Components
If you think the problem is caused by a hydraulic
component, start by checking the easy-to-reach items.
Check all hoses and lines for cracks, hardening, or other
signs of wear. Reroute any usable hoses that are kinked,
severely bent, or that rest against hot engine parts. Look
for leaks, especially at couplings. Replace any hoses or
lines that don't meet system flow and pressure ratings.
Next, go to the reservoir and filter or filters. Check fluid
level and look for air bubbles. Examine the filter; if it's
clogged, follow manufacturer's instructions for cleaning or
replacing it. A filter with a minimum 25 micron filtration is
recommended for the HGF system.
Visually check other components to see if they are
loosely mounted, show signs of leaks, or other damage
or wear.
It may be necessary that you perform hydraulic tests on
the pump and other hydraulic components. To do so,
consult the manuals published by the vehicle or
component manufacturers.

HGF Series Service Procedure

Troubleshooting Checklists
1. NOISE
NORMAL NOISE
A low hissing from the HGF control valve section during a turn
A noise from the system relief valve when it is actuated
Pump growl from some types of power steering pumps
ABNORMAL NOISE
A squealing noise during a turn may indicate that the belt or belts should be tightened or replaced
A clicking noise during a turn may indicate that some component is loose and shifting under load.

II. POSSIBLE STEERING PROBLEMS AND CAUSES
STEERING WANDER
Different size tires
Tire pressure incorrect or unequal left to right
Loose or worn steering linkage parts
Improperly adjusted or worn wheel bearings
In some vehicles, front end out of alignment
NO RECOVERY FOR OPEN-CYLINDER UNIT
Tire pressure low
Steering linkage parts binding
Tight front axle kingpins
Steering column binding or misaligned
SHIMMY
Improperly mounted tire or wheel
Components in steering linkage loose, worn, or out of adjustment
Wheels or brake drums out of balance
Wheel bearings improperly adjusted
Air in the hydraulic system
HIGH STEERING EFFORT IN ONE DIRECTION
Vehicle overloaded
Low hydraulic system pressure
Excessive system heat causing HGF plate valve to stick. See checklist under Excessive Heat.

HGF Series Service Procedure

HIGH STEERING EFFORT IN BOTH DIRECTIONS
Different size tires
Vehicle overloaded
Low hydraulic fluid level
Low flow or pressure from pump
Components in steering linkage binding
Restriction in fluid return line, or line too small
LOST MOTION (LASH) AT THE STEERING WHEEL
Steering wheel loose on column
Components in steering linkage loose or worn
HGF unit loose at mounting
Air in hydraulic system
EXCESSIVE HEAT [200° F MAXIMUM (93.3°)]
Undersized replacement hose or line
Kinked or severely bent hose or line
Restricted oil coolers
Restricted recentering of HGF unit
Excessive fluid flow

WARNING: IF THE HYDRAULIC SYSTEM FLUID BECOMES OVERHEATED [IN EXCESS OF 200°F (93.3° C)],
SEALS IN THE SYSTEM CAN SHRINK, HARDEN, OR CRACK, THUS LOSING THEIR SEALING ABILITY.

HGF Series Service Procedure

HGF COMPONENT ALIGNMENT GROOVE ILLULSTRATION

COMPONENTS OF THE HGF UNIT WITH ALIGNMENT GROOVES MUST BE
ASSEMBLED SO THAT THEIR ALIGNMENT GROOVES ARE POSITIONED AS
ILLUSTRATED FOR THE UNIT
TO FUNCTION CORRECTLY

IF THE HGF UNIT BEING DISASSEMBLED HAD A CONTACT
BRUSH ASSEMBLY, NOTE THE RADIAL POSITION OF IT'S
HOLE RELATIVE TO ALIGNMENT GROOVED SIDE OF THE
UNIT BEFORE DISASSEMBLY AND REASSEMBLE IN THE
SAME RADIAL POSITION.

HGF Series Service Procedure

HGF Exploded Assembly View-Typical

HGF Series Service Procedure

Item Number
1
2
3
3A
4
5
5A
5B
6
6A
7
7A
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
Jacket]
47
51
Jacket]
52

Description
Nut 5/16 UNF 24 (4)
Port Cover
Seal Ring (5)
Seal Ring (White)
O’Ring (3), (4) or (5)
Ball-7/32 inch (6mm) dia.
Relief valve cartridge
Coil spring
Plug
Hex plug
O’Ring, Plug & O’Ring assy.
O’Ring
Port Manifold
Spring, 3/4 inch (19mm) (3)
Hex Drive assy.
Alignment Pin (Needle Brg.) (9)
Valve Ring Matched Set
Valve Plate
Spring, 1/2 inch (13mm) (3)
Isolation Manifold
Drive Link
Metering Ring
Screw, Hex Socket Hd (11)
Seal, Commutator
Commutator Cover
Commutator Ring
Commutator
Spacer–Drive Link
Rotor Rotor Assy–Matched Set
Stator
Drive Plate
Spacer–Thrust Bearing
Thrust Bearing
Face Seal
Seal Spacer
Upper Cover Plate
Input Shaft/Wheel Tube
Retaining Ring
Washer–Retaining Plate
Retaining Plate
Matched Set
Upper Cover & Jacket Assy.
Bushing
Seal
Special Bolt, 5/16 24UNF-2A
Nut
Screw
Contact Ring Assy.
Contact Brush Assy.
Screw & Lock Washer
Washer [for 1-3/4 inch (45mm)

}

Horn Wire Cable Assy.
Spacer [for 1-1/2 inch (38 mm)
Ball 9/32 inch (22mm)

Items # 44, 45,46, 51 are not part of HGF service
assembly unit. They must be purchased as
separate items of order.

7D
HGF Series Service Procedure

Use with HGF Assembly View–Typical
2-8
Port Cover & Port Mainfold Kits
HGF 016015 X1(5 line) HGF 016016X1 (4 line)

1
Nut 5/16 UNF (4)
G103025

5
Ball 7/32 dia.
G453569

4
“O”Ring (5)
032758

6-7
Plug and “O” Ring
415585-A1

12-13
Valve Ring-Valve Plate Matched Set
HGF 014000 A1
20
Commutator Cover
HGF 014001

Seal Kit
SK 000097

(

3
032755 (5)

HGF
08
10
12
16
20

35
Washer
028493

4
032758 (5)
38
Bushing
063042

10
Hex Drive Assy
HGF 013001 A1

7
032645
39
Seal Dust
402405

27
Spacer Thrust Bearing
4773000

31
Seal Spacer
477297
7A
032750

11
Alignment Pin
040147 X1
19
Seal Commutator
032724

26
Drive Plate
HGF 013000

30
Back-up Ring
032770

3A
032832

3A
Seal Ring (White)
032832

16
Drive Link
HGF 013002

15
Isolation Manifold
HGF 015000

29
Face Seal
032763

34
Retaining Rings
401465
Items ‰

9 & 14
Spring Kit
401443X1
(3) 401443
(3) 401608

21-22
Commutator-Commutator Ring
HGF 014002 A1

28
Thrust Bearing
069020

3
Seal Ring
032755 (5)

32
Upper Cover Plate
HGF 016012
19

032724

29
478046

)

All other column parts per specification.

18 (11)

24-25

40(4)

Metering Ring
HGF019007
HGF019008
HGF019009
HGF019010
HGF019011

Screw Hex
0213470100
0123480112
0213470125
0213470150
0123470175

Rotor Assy.
HGF087000
HGF107000
HGF127000
HGF167000
HGF207000

Spacer Drive Link
4773010022
4773010034
4773010047
4773010072
4773010097

Special Bolt
0213810406
0213810406
0213810431
0213810456
0213810481

Tools Materials Required for Servicing
HGF Service Manual
HGF service ass'y fixture (See Figure 1)
Clean, petroleum-based solvent
Vise
Pliers
Screw driver
Blunt ended punch
6 pieces of .007 inch (.18 mm) shim stock, approximately

Figure 1

.5 inch (13 mm) wide x 1.5 inch (38 mm) long.
External retaining ring pliers
Tape, plastic electrical

CONVERSIONS
INCHES
mm
4.6
0.18
9.5
0.375
51.0
2.0
82.6
3.25
101.6
4.0
203.2
8.0

Breaker bar
Sockets: 1/2, 7/8 inch
3/32 inch Allen wrench socket
T-30 Torq socket
Slot type screw driver socket
5/16-24 UNF hex nut (4) required
3/4 inch (19 mm) to 7/8 inch (22 mm) bearing puller
Clean grease
Light weight oil
Torque wrenches: 11–13 in. lb. & 25–35 ft.lb. or Newton Meter
Feeler gauge .003 in. (.08 mm) or .005 in. (.13 mm)
(See disassembly procedure #37)
Electrical continuity checking device

Torque Chart
Part Name
Socket Head Cap Screws
Plug and O-Ring Ass'y
Plug and O-Ring Ass'y
Hex Nut 5/16-24
Jam Nut 5/8-18
Jam Nut 13/16-20 UNEF

Exploded View
Item Number
18
6, 7
6A, 7A
1
41
41

Torque
11-13 in-lbs. (1.24-1.47 N m)
8-12 ft-lbs. (11-16 N m)
25-35 ft-lbs. (34-48 N m)
18-22 ft-lbs. (25-30 N m)
25-30 ft-lbs. (34-41 N m)
30-40 ft-lbs. (41-55 N m)

HGF Series Service Procedure

HGF: Disassembly and Inspection
Preparation before disassembly
Before you disassemble the HGF Hydraguide unit or any
of its parts, read this entire manual. It provides important
information on parts and procedures you will need to
know to service the HGF.
When disassembling any of the parts, use a clean work
bench. Wash all parts in clean petroleum based solvent
and blow them dry. Keep each part separate to avoid
nicks and burrs.
WARNING: SINCE THEY ARE FLAMMABLE, BE
EXTREMELY CAREFUL WHEN USING ANY SOLVENT.
EVEN A SMALL EXPLOSION OR FIRE COULD CAUSE
INJURY OR DEATH.
WARNING: WEAR EYE PROTECTION AND BE SURE
TO COMPLY WITH OSHA OR OTHER MAXIMUM AIR
PRESSURE REQUIREMENTS.
WARNING: REMOVE STEERING WHEEL WITH A
STEERING WHEEL PULLER AFTER REMOVING
WHEEL NUT. DO NOT LOOSEN WITH HAMMER, AS
THIS COULD DAMAGE UNIT INTERNALLY.
Before you disconnect any hoses, clean off all outside
dirt from around the fittings. Plug the port holes and
hoses immediately after you disconnect the hoses and
before you remove the HGF from the vehicle. This is to
prevent foreign matter from entering the HGF and
damaging it when you clean and reassemble it.

Remove contact brush
assembly & related
components

Remove any contact brush cover (49) contact brush
cover seal (48) and related screw and lock washers (50),
and disconnect any horn wire connection to the HGF
unit. Next, remove nuts from the mounting bolts, blow the
unit dry and place it on a work bench.
Components throughout this assembly are stacked on
four bolts and held in alignment with alignment pins
designed to be a slip fit into the components. Use the
minimum force necessar y and maximum care to
separate or assemble the components.
The HGF Hydraguide unit has several components that
are of brazed laminate construction, plates and parts
bonded together per manently to for m an integral
component that is not subject to disassembly for service.
Disassemble the HGF unit only to the extent shown in
this manual.
CAUTION: Do not force or abuse closely fitted parts,
or you may damage them. Use only genuine Ross or
OEM approved service parts.
The components, required to service an HGF unit and
their service part numbers are available from authorized
OEM par ts distr ibutors or other author ized HGF
distributors.

1. Remove screw and lock washers
(45) and contact brush assemblies
(44) and washers (46) or spacer
(51) from the upper cover and
jacket tube assembly (37) if the
HGF unit is so equipped. See
FIGURE 2.

Figure 2

HGF Series Service Procedure

Place HGF unit in
service fixture

NOTE

Loosen plug assembly

Remove port cover nuts

2. To avoid distorting or
damaging the HGF unit, do
not clamp it directly into a
vise. Clamp a service
assembly fixture described
in FIGURE 1 securely in a
vise, See FIGURE 3, and
place the HGF unit, input
shaft/wheel tube first, into
the service assembly fixture.
Attach the unit to the fixture
with four 5/16-24 UNF nuts.
See FIGURE 4.

NOTE: Before beginning the
disassembly of HGF unit, study the
relative positions of the alignment
grooves on the side of the components
in the assembly. Also, note the jacket
tube contact brush cover hole radial
position relative to the side of the unit
with the alignment grooves. The
relative alignment groove positions on
the components and the jacket tube
contact brush cover hole positions
must be maintained at reassembly.
Refer to the alignment groove graphic
on fold-out.

3. Loosen plug (6) or hex plug
(6A) assembly in the port
cover (2) for disassembly
after the port cover is
removed from the unit. Use
an appropriate type
screwdriver, T-30 Torx driver
or 7/8 inch hex socket. See
FIGURE 5.

Figure 3

Figure 4

Figure 5

4. Remove the four retaining
nuts (1) from the port cover
(2) assembly. Be careful not
to damage the protruding
ports. See FIGURE 6.
Replace any nut that has
damaged threads or hex.

Figure 6
HGF Series Service Procedure

Remove port cover

5. Grasp the port cover (2)
assembly and lift it from the
unit. Discard three, four, or
five seal rings (4) and seal ring
(3) or if included white seal
ring (3A). See FIGURE 7.
Remove loose check ball (52)
from top of port manifold (8) if
included.

Remove plug

6. If included, remove the
loosened plug (6) and o-ring
(7) assembly from the port
cover. Be ready to catch the
steel check ball (5) as it falls
from its cavity. Discard o-ring
(7). See FIGURE 8.

Remove hex cap &
relief valve cartridge &
spring assy.

Inspect port cover

7. Inspect the port cover (2) for
port fitting sealing surface
scratches and thread damage.
Replace port cover, if these
conditions are evident.

Remove port manifold

8. Carefully lift the port manifold
(8) (3 plates bonded together)
from the unit. See FIGURE 9.

NOTE

Remove springs
NOTE

Inspect springs

6A. If included, removed the
loosened hex plug (6A) and oring (7A) from the port cover
(2). Discard o-ring. Remove
relief valve cartridge (5A) and
spring (5B) assembly. A bent
or lost spring (5B) can be
serviced separately. See
FIGURE 8A. Do not try to
disassemble relief valve
cartridge (5A).

HGF Series Service Procedure

NOTE: Be prepared to catch
three springs (9) which may
become disengaged when
removing the port manifold.

Figure 7

Figure 8

Figure 8A

9. Remove three springs (9) from
the port manifold (8).
NOTE: The unit has two different
length spring sets. The set you have
just removed from the port manifold
are three-quarter inch (19 mm) long.
Keep this set of three springs
separate from the next set of three
springs to be removed.
10. Inspect the springs for bent or
distorted coils. If a spring is
broken or deformed, all six springs
in the unit should be replaced.

Figure 9

Inspect port
manifold

CAUTION

11. Inspect the ground surfaces of
the port manifold (8). You
should notice a "normal"
polished pattern due to the
rotation of the valve plate (13)
and hex drive assembly (10).
All edges should be sharp and
free of nicks and burrs. The
surfaces of the port manifold
should be free of scratches or
scoring. If any of these wear
conditions exist, replace the
port manifold.
CAUTION: Many components
in the unit have finely ground
surfaces. Be careful not to
nick or scratch these surfaces.

Remove valve ring

12. Remove the valve ring (12),
discard the two seal rings (3).
See FIGURES 10 and 11. The
valve ring should be free of
nicks and scoring.

Remove valve plate

13. Remove the valve plate (13) by
lifting it from the isolation
manifold (15).

Inspect valve plate

14. Inspect the slot edges and
ground surfaces. If the valve
plate (13) shows nicks or
scoring or the edges are not
sharp, it must be replaced.
See FIGURE 12.
NOTE: The valve ring (12)
and valve plate (13) are a
matched set and must be
replaced as a set.

NOTE

Remove springs

NOTE

Figure 10

Figure 11

Figure 12

15. Remove three springs (14)
from the isolation manifold (15)
pockets. See FIGURE 13.
NOTE: The unit has two
different length spring sets.
The set you have just removed
from the isolation manifold is
one-half inch (13 mm) long.
Keep this spring set separate
from the set removed from the
port manifold (8).

Figure 13
HGF Series Service Procedure

Inspect springs

16. Inspect the springs (14), for
bent or distorted coils. If a
spring is broken or deformed,
all six springs in the unit must
be replaced. See FIGURE 14.

Figure 14
Remove hex drive
assembly

17. Remove hex drive assembly
(10) from drive link (16). See
FIGURE 15.

Inspect hex drive
assembly

18. The pin in the hex drive
assembly (10) should not show
wear and must be firmly
pressed in place. The sides of
the hex and the slot should
not have grooves or scoring. If
the hex drive assembly (10)
shows signs of this type of
wear, it must be replaced.

Remove alignment pins

NOTE

Figure 15

19. Remove the two alignment
pins (11) that align the port
manifold (8), valve ring (12)
and isolation manifold (15).
See FIGURE 16.
NOTE: A service kit of nine
alignment pins (11) is available for
servicing the unit.

Figure 16
Remove isolation
manifold

20. Remove the isolation manifold
(15), (four plates bonded together).
See FIGURE 17.

Figure 17
13

HGF Series Service Procedure

Inspect isolation
manifold

Remove alignment pins

21. Inspect the ground surfaces of
the isolation manifold (15).
You should notice a "normal"
polished pattern due to the
rotation of the valve plate (13)
and on the opposite side a
"normal" polished pattern due
to the action of the commutator
cover (20) and commutator
seal (19). The holes and
edges should be free of nicks.
The manifold surfaces should
be free of nicks or scoring. If
the manifold has developed
any of these conditions, it must
be replaced.

Figure 18

22. Remove the two isolation
manifold-metering ring
alignment pins (11). See
FIGURE 18.
23. Remove the drive link (16)
from the unit. See FIGURE 19.

Figure 19
Inspect drive link

24. Inspect each end of the drive
link (16). The four crowned
contact surfaces should not be
worn or scored. Replace if
wear or scoring is evident.

Remove & inspect
metering ring

25. Remove the metering ring (17)
and discard the two seal rings
(3). See FIGURE 20. If the
metering ring bore is scored, it
should be replaced.

Figure 20
Remove metering
package

CAUTION

26. The "metering package"
components are held together
with eleven hex. socket head
screws. Lift the metering
package from the assembly,
and place it on a clean surface.
See FIGURE 21.
CAUTION: Do not clamp the
metering package in vise, as
this could damage the
components.

Figure 21
HGF Series Service Procedure

Remove commutator
seal

27. Remove and discard the
commutator seal (19) from the
commutator cover (20). See
FIGURE 22.

Figure 22
Remove cap screws

28. Remove the eleven hex.
socket head screws (18), that
hold the metering package
together. See FIGURE 23.
Use a 3/32 inch Allen wrench.
Inspect screws for thread and
socket damage and replace as
required.

Remove commutator
cover

29. Lift the commutator cover (20)
from the metering package.

Figure 23
Inspect commutator
cover

30. Inspect the ground surfaces of
the commutator cover (20).
You should notice a "normal"
polished pattern due to the
rotation of the commutator
(22). If the cover has nicks,
burrs, or scoring, it must be
replaced. See FIGURE 24.

Figure 24
Remove commutator
ring
CAUTION

31. Remove commutator ring (21).
See FIGURE 25. Inspect for
cracks, burrs, and scoring.
CAUTION: Handle commutator
ring with care, as it is easily
broken.

Figure 25
15

HGF Series Service Procedure

Remove commutator

CAUTION

32. Remove the commutator (22)
from the rotor (24). See
FIGURE 26.
CAUTION: Five alignment pins (11)
connect the commutator to the
rotor with a slip fit. Care and
minimum force should be used to
separate the two components.

Figure 26
Remove alignment pins

33. Remove the five alignment
pins (11). See FIGURE 27.

Remove & inspect drive
link spacer

34. Remove drive link spacer (23).
See FIGURE 28. Replace it, if
it is grooved or worn.

Inspect commutator

35. The commutator (22) is made
up of two round plates pinned
and bonded together as a
permanent assembly and is
not subject to further
disassembly. Inspect the
ground surfaces of the
commutator. The holes and
edges should be free of nicks.
The ground surfaces should be
free of scoring. The edges
should be sharp.

NOTE

Inspect rotor set

NOTE

NOTE: The commutator (22)
and commutator ring (21) are a
matched set. If either is worn
or damaged, you must replace
the set.

Figure 27

Figure 28

36. With the rotor set (24, 25) lying
on the drive plate (26), the
rotor (24) should rotate and
orbit freely within the stator
(25). The commutator side of
the stator face must be free of
grooves or scoring.
NOTE: The rotor (24) and
stator (25) are a matched set.
You must replace them as a
matched set, if either is worn
or damaged.

HGF Series Service Procedure

Check rotor to stator
"tip" clearance

Remove rotor set

NOTE

Inspect drive plate

CAUTION
Remove face seal
and spacer

NOTE

37. Check the rotor (24) lobe "tip"
to stator (25) lobe "tip"
clearance, using the
appropriate feeler gage. See
FIGURE 29. The rotor lobe,
directly across from the rotor
lobe tip being gaged, (see
pointer FIGURE 29) must be
centered between stator lobes
during the gaging process. A
rotor and stator that is .75
inches (19 mm) or less in
height has a maximum
allowable "tip" clearance of
.003 inches (.08 mm). A rotor
and stator that is 1.00 inch
(25.4 mm) or more in height,
has a maximum allowable "tip"
clearance of .005 inches (.13
mm). A rotor and stator that
exceeds the maximum
allowable "tip" clearance, must
be replaced.
38. Remove the rotor set (24, 25),
from the drive plate (26). The
drive plate side of the rotor set
also must be free of grooves or
scoring.

Figure 29

Figure 30

NOTE: Handle the rotor set
carefully to avoid nicks and
scratches.
39. The rotor side of the drive plate
(26) should show the "normal"
spiral pattern due to rotor
movement. Inspect the thrust
bearing side of the plate for
brinelling (dents) or spalling
(flaking). The flat sides of the
input shaft engagement hole
should not be grooved or worn.
If any of these conditions are
present, the drive plate (26)
must be replaced. See
FIGURES 30 and 31.
CAUTION: Protect seal
surface from damage.

Figure 31

40. Remove face seal (29) and face
seal spacer (31) from upper cover
plate (32). See FIGURE 32.
Discard the face seal (29).
Retain metal spacer (31).
NOTE: Back up ring (30) may be an
integral part of face seal (29) on some HGF
units. Old style seal may have back-up ring;
remove and discard.

Figure 32
17

HGF Series Service Procedure

Remove thrust bearing
& spacer

41. Note position of bearing spacer
undercut (groove-side down).
Remove thrust bearing (28) and
bearing spacer (27) from upper cover
plate (32). See FIGURE 33.

Inspect bearing and
spacers

42. Inspect the thrust bearing (28)
for brinelling (dents) or spalling
(flaking), if either exists, or if
one of more of the rolls is lost
or broken, replace the bearing
assembly. See FIGURE 33.
Replace seal spacer (31) or
bearing spacer (27) if worn or
broken.

CAUTION

CAUTION: The thrust bearing
assembly (28) will have 16 or 17 rolls
evenly spaced in a roller cage that
can hold 32 or 34 rolls or the thrust
bearing will have a full complement
of 32 or 34 rolls. The bearing
assembly with 32 or 34 rolls should
not be replaced with a bearing
assembly that has 16 or 17 rolls.

NOTE

NOTE: For reassembly purposes,
note the radial position of the
alignment grooved edge of the upper
cover plate (32) relative to the jacket
tube contact brush hole if the unit is
so equipped.

Remove and inspect
upper cover plate

CAUTION
Remove dirt and water
seal

Remove input
shaft/wheel tube

NOTE

Figure 33

Figure 34

43. Remove the upper cover plate (32)
(four plates bonded together). Inspect
the upper cover plate. You should
notice some polishing due to the
action of the seal. The plate should
be free of brinnelling (dents) or
spalling (flaking). If it is damaged, the
upper cover plate must be replaced.
See FIGURE 34.
CAUTION: Protect seal area.
44. Slide the seal (39) from the
jacket tube. If the seal is worn
or damaged, it must be
replaced. See FIGURE 35.

Figure 35

45. Remove the input shaft/wheel
tube (33) assembly, sliding it
out of the upper cover end of
the assembly. See FIGURE 36.

NOTE: If the input shaft/wheel
tube assembly has 7/8
serrations or contact ring
assembly (43), the washer (35)
and retaining plate (36) will be
removed with input shaft/wheel
tube assembly.

Figure 36
HGF Series Service Procedure

Inspect input
shaft/wheel tube subassembly

NOTE

Remove retaining ring

47. Using appropriate external
retaining ring pliers, remove the
retaining ring (34) from the input
shaft/wheel tube (33). See
FIGURE 37. Discard, if deformed
or broken.

Remove retaining plate

48. Remove washer (35) and retaining
plate (36) from input shaft/wheel
tube (33) or upper cover and jacket
assembly (37). Discard, if
deformed or damaged. See
FIGURE 38.

NOTE

Remove horn cable and
contact ring assemblies

46. Inspect the input shaft/wheel tube
(33) and sub-assembly
components as assembled.
Inspect input shaft/wheel tube for
worn or damaged serrations,
wheel nut threads, bearing
diameter, and flats on the lower
end. Inspect the other
components of the sub-assembly
for wear damage. If the subassembly includes horn cable
assembly(ies), check its electrical
functions with an appropriate
continuity checking device. If this
sub-assembly passes inspection,
set it aside, and go to disassembly
procedure number 50. If it does
not pass inspection, continue with
disassembly procedure number
47.
NOTE: There must be electrical
continuity (connection) from the upper
terminal of horn cable assembly (47)
to the contact ring of the contact ring
assembly (43). There must not be any
electrical continuity (connection) from
horn cable assembly terminal or
contact ring assembly to the input
shaft/wheel tube (33) or other
components.

HGF Series Service Procedure

Figure 37

Figure 38

Figure 39

NOTE: Retaining plate (36) cannot be
serviced separately, but is a part of an
upper cover and jacket tube assembly
service kit.

49. Remove tape, horn cable
assembly (47), screw (42), and
contact ring assembly (43)
from input shaft/wheel tube
(33) if the unit is so equipped.
Replace broken or electrically
defective components. See
FIGURES 39 and 40.

Figure 40

NOTE

NOTE: The relative positioning of the
contact ring(s) (43) should be noted
before removal for reassembly
purposes.

Remove upper cover
and jacket tube
assembly

50. Remove the upper cover and jacket
tube assembly (37) and lay the
assembly on the bench. See FIGURE
41.

Inspect upper cover
and jacket tube
assembly

51. The jacket tube has been pressed into
and welded to the upper cover plate
support tube such that the retainer
plate (36) is flush with the upper cover
plate surface when seated against the
jacket tube. Any signs of looseness or
movement of jacket tube in the upper
cover support tube will require
replacement of upper cover and jacket
tube assembly (37), retainer plate (36)
and bushing (38) as a set. A loose or
worn input shaft/wheel tube bushing
(38) in the upper cover and jacket tube
assembly can be serviced separately.

Remove worn bushing

52. If the bushing (38) is to be replaced,
place the upper cover and jacket tube
assembly (37) in a vise with the vise
jaws clamping firmly on the jacket
tube without deforming the jacket
tube. Using an appropriate type of
pliers, "uncrimp" or relieve the two
crimped areas on the bushing end of
the jacket tube. Remove the bushing
using a bearing or seal type puller and
discard the bushing. Set the upper
cover and jacket tube aside to await
assembly. See FIGURES 42, 43.

Remove and inspect
bolts

WARNING

53. Remove the nuts holding the four
bolts (40) to the fixtures and remove
the bolts. Bolts with the square
shoulder or the threads damaged
such that the nuts cannot be properly
torqued must be replaced. See
FIGURE 44.

Figure 41

Figure 42

Figure 43

WARNING: USE ONLY GENUINE
OEM APPROVED REPLACEMENT
PARTS. THE USE OF IMPROPER
PARTS COULD CAUSE A LOSS OF
STEERING WHICH COULD LEAD TO
AN ACCIDENT.

The HGF disassembly is complete.

Figure 44
HGF Series Service Procedure

HGF: Assembly
Replace gaskets, seals
and O-Rings

Replace all seals and "O" rings with new
ones each time you assemble the HGF
unit. Be sure the seal and "O" rings
remain seated correctly when components
are assembled. See FIGURE 45.

NOTE

NOTE: A seal kit with all required seals
except the column and jacket seal is
available for service. The seal (39) is
available separately.

Clean and dry parts

Before you reassemble the HGF, wash all
parts in clean petroleum based solvent.
Blow them dry with compressed air.

WARNING

WARNING: SINCE THEY ARE
FLAMMABLE, BE EXTREMELY
CAREFUL WHEN USING ANY SOLVENT.
EVEN A SMALL EXPLOSION OR FIRE
COULD CAUSE INJURY OR DEATH.

WARNING

WARNING: WEAR EYE PROTECTION
AND BE SURE TO COMPLY WITH OSHA
OR OTHER MAXIMUM AIR PRESSURE
REQUIREMENTS.

Place bolts into fixture

1. Place four bolts (40) into fixture
with shortest threaded end of bolts
through the fixture holes. Secure
bolts to fixture with four 5/16 24
UNF nuts. Tighten nuts to secure
assembly to fixture but loose
enough to turn bolts and facilitate
stacking of components. See
FIGURE 46.
2. If the bushing (38) was removed
from the upper cover and jacket
tube (37) for replacement, press a
new bushing (38) into the upper
end of the jacket tube with the end
of the bushing that has recesses
toward the jacket tube. This may
be done using an arbor press or
clamping on the jacket tube per
disassembly step 52 and using the
wood handle end of a hammer.
The bushing must be seated firmly
in the jacket tube and below the
end of the jacket tube. "Crimp" the
end of the jacket tube over the
bushing in two places
approximately 90° away from the
original crimped areas, using pliers
and/or a blunt ended punch. See
FIGURES 47 and 48.

Assemble new bushing

HGF Series Service Procedure

Figure 45

Figure 46

Figure 47

Figure 48

Stack upper cover and
jacket tube assembly

NOTE

3. Apply clean grease to bushing (38)
and stack upper cover and jacket
tube assembly (37) on the four
bolts (40) with the jacket tube
pointing down through the hole in
the fixture. Make sure the square
shoulder of the bolts engage the
square holes in the upper cover.
See FIGURE 49.
NOTE: If contact ring assemblies
and horn wires are not required,
go to assembly Step 6.

Install contact ring
assembly

4. Install the contact ring
assembly(ies) (43), if required,
onto the input shaft/wheel tube
(33) into the same position as
before disassembly. See FIGURE
50.

Install horn cable
assembly

5. Insert horn cable assembly (47)
spade terminal end first into the
steering wheel end of the input
shaft/wheel tube (33) so that it
exits from the horn cable outlet
hole. Push the horn cable spade
terminal onto the contact ring (43)
terminal connector. Be sure it is a
good, firm connection. Position
the horn cable protector sleeve so
that it protects the horn cable from
any sharp corner where it exits the
horn cable outlet hole. Position
and fasten the contact ring
assembly (43) with screw (42).
Use about 1 1/2 turns of tape
around the input shaft/wheel tube,
horn cable and contact ring to hold
the horn cable in place. See
FIGURE 51. Check for electrical
continuity (connection) required
from horn cable assembly (47)
upper terminal to contact ring of
contact ring assembly (43). There
must not be electrical continuity
(connection) from upper horn
cable terminal or contact ring to
input shaft/wheel tube (33). Also,
see FIGURES 99 and 100.

CAUTION

Figure 49

Figure 50

Figure 51

CAUTION: Failure to check the electrical
functions of the input shaft/wheel tube,
horn cable assembly before it is
assembled into the HGF unit, would
require another complete disassembly
of the unit if proved electrically defective
after the HGF unit is assembled.
HGF Series Service Procedure

Install retaining plate
and washer

Install retaining ring

Install input shaft/wheel
tube

6. Apply small amount of grease to
the recessed face of retainer plate
(36) and to washer (35). If the
input shaft/wheel tube (33) is 3/4
inch (19 mm) diameter with no
contact ring assembly (43), place
the retainer plate into the upper
cover and jacket assembly (37)
with recessed retainer face out.
Place washer (35) against
recessed face of retainer plate.
If input shaft/wheel tube (33) is 7/8
inch (22 mm) diameter on the hand
wheel end or has a contact ring
assembly (43), slide the retainer plate
(36) then the washer (35) onto the
retaining ring groove end of the input
shaft/wheel tube, past the ring
groove. The recessed face of the
retaining plate must be toward the
washer. See FIGURE 52.
7. Install retaining ring (34) onto input
shaft/wheel tube (33) using the
appropriate external retaining ring
pliers. See FIGURE 53.

Figure 52

Figure 53

8. Slide input shaft/wheel tube (33)
assembly into upper cover end of
upper cover and jacket tube
assembly (37) and through the
bushing (38) until the retaining ring
(34) bottoms against washer (35)
which bottoms against retainer
plate's (36) recessed face and the
retainer plate seats against the
end of jacket tube. See FIGURES
54 & 55.

Figure 54
Install upper cover plate

9. Assemble the upper cover plate
(32) over the four bolts (40) and
input shaft/wheel tube (33) onto
the upper cover and jacket tube
assembly (37) with the highly
polished surface up and the edge
with the alignment groove in the
same position relative to the jacket
tube contact brush cover hole as
noted before disassembly. See
FIGURE 55. (Reference
alignment groove graphic--fold-out
page.)

Figure 55
23

HGF Series Service Procedure

Grease upper cover
plate face

10. Apply clean grease to the face of
the upper cover plate (32), to the
drive plate end of the input
shaft/wheel tube (33) and to the
face seal (29). See FIGURE 56.

Figure 56
Install face seal

11. Install face seal and spacer (31)
assembly over end of input
shaft/wheel tube (33) onto upper
cover plate (32). See FIGURE 57.

Figure 57
Assemble
package

metering

12. Place the drive plate (26) on a
clean lint-free surface with the
eleven tapped holes facing up.
Place the rotor set (24,25) on top
of the drive plate with the five pin
holes facing up. Rotate the stator
(25) until the eleven hex. socket
head screw relief slots are aligned
with the tapped holes in the drive
plate. See FIGURE 58.

Figure 58

HGF Series Service Procedure

Install spacer

13. Apply a small amount of clean
grease to spacer (23) and insert it
into the drive slot in the rotor (24).
See FIGURE 59. The grease will
aid in retaining the spacer during
other assembly procedures.

Figure 59

Figure 60
Install commutator

CAUTION

14. Place the commutator (22) on top
of the rotor (24). Be sure the
correct surface, shown in FIGURE
60, is toward the rotor. Align the
five holes and press the five
alignment pins (11) in place. See
FIGURE 61.
CAUTION: Make sure the five
alignment pins are pressed below
the surface of the commutator (22).

Figure 61
Lubricate the
commutator

15. Place a few drops of oil into each
recess in the commutator (22). See
FIGURE 62.

Figure 62
25

HGF Series Service Procedure

Install commutator ring

16. Place commutator ring (21) either
side up on top of stator (25). Align
commutator ring screw recesses
with stator screw slots. See
FIGURE 63.

Figure 63
Install commutator
cover

17. Place commutator cover (20) on
top of commutator ring (21) with
flat surface toward commutator.
Align screw holes in cover, with
screw holes in drive plate (26).
See FIGURE 64.

Figure 64
Install cap screws

NOTE

18. Screw the eleven hex. socket
head cap screws (18) loosely into
metering package. See FIGURE 65.
NOTE: The commutator ring (21)
must be concentric with drive plate
(26) within .005 inch (.127 mm) total
indicator reading after tightening the
eleven hex. socket head cap screws
(18). The next two procedures are a
method of achieving the concentricity.

Figure 65
Align commutator ring
concentrically with
drive plate

19. Place the metering ring (17) on a
hard flat surface. Place the
assembled metering package into
the metering ring with the
commutator cover (20) down, such
that the drive plate is partially out
of the metering ring. (A suitable
wood block under the metering
package will hold it in this
position.) See FIGURE 66.

Figure 66
HGF Series Service Procedure

Place one piece of .007 inch (.18
mm) shim stock approximately .5 inch
(13 mm) wide x 1.5 inch (38 mm) long
between the metering ring and drive
plate in three places approximately
equal distance around the outside
diameter of the drive plate. Place
another piece of the .007 inch (.18
mm) shim stock between the drive
plate and each of the three pieces of
shim stock already in place. Lift the
metering ring and metering package
and remove the wood block. Push
the metering package and shims into
the metering ring until the drive plate
and shims are at least flush with the
metering ring. See FIGURE 67.

Tighten hex socket
head cap screws

WARNING

Install drive link

CAUTION

HGF Series Service Procedure

20. Reverse the metering ring (17)
and metering package as a unit on
the flat surface. Push down on the
metering package until the drive
plate is on the flat surface. Be
sure the cap screws (18) are loose
enough to allow the commutator
ring (21) and drive plate (26) to
align themselves concentrically in
the metering ring bore. Gradually
tighten the eleven cap screws,
following the sequence shown in
FIGURE 70, at least twice until a
final torque of 11-13 inch pounds
(1.24 to 1.47 N m) is reached.)
See FIGURES 68 and 69.
Remove the metering package
and shims from the metering ring.
Discard the shims.
WARNING: USE CARE AND EYE
PROTECTION WHILE ADDING AND
REMOVING SHIMS FROM
METERING RING AS THE SHIMS
WILL BE UNDER SPRING TENSION
AND COULD FLY INTO THE AIR
CAUSING INJURY.

Figure 67

Figure 68

Figure 69

21. Inser t large tang of the dr ive link
(16) into the slot in the rotor (24).
See FIGURE 70.

CAUTION: An incorrect (reversed)
assembly of the drive link will
prohibit the assembly of the hex
drive (10) in step 35.

Figure 70

Check rotor movement

22. Grasp the drive link (16) and rotate
the metering package by hand to
make sure the parts do not bind.
The rotor (24) should orbit inside
the stator (25). If they bind,
disassemble the metering
package, correct the cause, and
repeat the assembly and
concentricity procedures. See
FIGURE 71.

Install metering ring

23. Apply clean grease to the metering
ring seal ring (3). Position the seal
ring in the metering ring seal
groove opposite to the end with
the alignment pin holes. Stack the
metering ring (17) into place, over
the four bolts (40), with the seal
ring towards the upper cover plate
(32), and an alignment pin hole on
the metering ring in line with and
on the same side as the alignment
groove on the side of the upper
cover plate. See FIGURE 72.
This is required so that the other
components can be aligned
correctly.

CAUTION

Install bearing spacer

Figure 71

Figure 72

CAUTION: Be sure the seal ring (3)
does not slip from position.

24. Place the bearing spacer (27) onto
the face of the upper cover plate
(32). Position of undercut is
down. See FIGURE 73.

Figure 73
Install bearing

25. Lightly grease roller thrust bearing
(28), and place it on the upper
cover plate (32), inside the bearing
spacer (27). See FIGURE 74.

Figure 74
HGF Series Service Procedure

Install metering
package

26. Inspect the exposed face of the
drive plate (26) making sure it is
clean and lint free. Apply a small
amount of clean grease on the
drive plate. Place the "metering
package", drive plate side first,
into the metering ring (17).
Revolve the input shaft (33) or
metering package until the hole in
the drive plate (26) engages the
end of the input shaft and the drive
plate is seated on the thrust
bearing (28). When properly
seated, the metering package will
be below the surface of the
metering ring. See FIGURES 75
and 76.

Figure 75

Figure 76
Install commutator seal

27. Grease the new commutator seal
(19) and place it into the
commutator cover (20) seal
groove. The rubber portion (the
softer side) of the seal with the
yellow mark must be placed into
the seal groove. See FIGURE 77.

Figure 77
Install metering ring
seal ring

28. Apply clean grease to the metering
ring seal ring (3). Place the seal ring
into the metering ring seal ring
groove. See FIGURE 78.

Figure 78
29

HGF Series Service Procedure

Install alignment pins

29. Place two alignment pins (11) into
the metering ring (17). See
FIGURE 79.

Figure 79
Install isolation
manifold

Install two alignment
pins

30. Stack the isolation manifold (15) (4
plates bonded together) onto the
metering ring (17), aligning the
grooves on the side of the
manifold with the grooves on the
side of the upper cover plate (32)
and the alignment pin holes with
the alignment pins in the metering
ring. The isolation manifold
surface without the recessed slots
must be placed toward the
metering ring. See FIGURE 80.

Figure 80

31. Install two alignment pins (11) into
the isolation manifold (15). See
FIGURE 81.

Figure 81
Install 1/2 inch springs

NOTE

32. Place the three 1/2 inch (13 mm)
springs (14) into the spring
pockets of the isolation manifold
(15). See FIGURE 82.
NOTE: Two different length springs
are used in the unit. Be sure to use
the 1/2 inch (13 mm) length springs
(14) during this part of the assembly.

Figure 82
HGF Series Service Procedure

Install valve ring

CAUTION

33. Apply clean grease to a seal ring
(3) and place it in the valve ring
(12) recess that will face down
when installed. Install the valve
ring over the bolts and alignment
pins with seal ring facing the
isolation manifold (15). See
FIGURE 83.
CAUTION: Be sure seal ring is
seated correctly after valve ring is
assembled.

Figure 83
Install hex drive
assembly

NOTE

34. Place hex drive assembly (10),
pin side up, through the hole in the
isolation manifold (15). The slot in
the hex drive must be engaged
with the small tang of the drive link
(16). Turn the input shaft/wheel
tube to assist the engagement.
See FIGURE 84.
NOTE: If hex drive does not readily
assemble on drive link, see CAUTION
note after assembly step 22.

Figure 84
Install valve plate

HGF Series Service Procedure

35. To install the valve plate (13)
correctly, first carefully study
FIGURES 85 and 86 for
positioning of the valve plate (13)
spring slots and its other cavities in
relation to the spring and spring
recesses on the isolation manifold
(15). Be sure to use the alignment
grooves on the side of the isolation
manifold for orientation. Place the
valve plate (13) with the surface that
reads "shaft side" down over the hex
drive assembly (10) aligning the three
spring slots centrally over the three
springs placed in the spring recesses
of the isolation manifold (15). The
valve plate spring slot with the small
cavity and then the words "port side"
centrally below it as pointed to in
FIGURE 85, must be placed over the
spring and spring recess in the
isolation manifold at the top (at 12
o'clock) as shown in FIGURES 85
and 86. Adjust the valve plate
position radially to centralize the
spring slots over the springs and the
spring recesses in the isolation
manifold.

Figure 85

Figure 86

CAUTION

CAUTION: The unit will not
function if the valve plate is not
positioned on the isolation
manifold exactly as shown in
FIGURE 86. If the valve plate
spring slots, isolation manifold
spring recesses and springs are
not centrally aligned in this step,
the springs could be damaged
when the port manifold is placed
on the assembly.

Figure 87
Install valve ring seal
ring

36. Apply clean grease to the valve
ring seal ring (3). Install seal ring
in the valve ring (12). See
FIGURE 87.

Install 3/4 inch springs

37. Place port manifold (8) valve side
up on a clean surface. Install
three 3/4 inch (19 mm) springs (9)
into the spring pockets. See
FIGURE 88.

Install port manifold

38. Apply a few drops of oil to the
valve plate (13). Align the grooves
on the side of the port manifold (8)
with the grooves on the side of the
isolation manifold (15) and
assemble the port manifold with
the springs toward the valve plate
(13). Be careful not to pinch a
spring during installation. The two
alignment pins (11), in the valve
plate, will engage the holes in the
port manifold. The pin on the hex.
drive assembly (10) must engage
the center hole in the port
manifold. See FIGURE 89.

Install check ball

Figure 88

Figure 89

39. Install new "O" ring (7) on plug (6),
insert check ball (5) into check ball
hole in port cover (2). Be sure ball
(5) is seated in bottom of check
ball hole. Turn plug assembly (6,
7), into port cover (2) until ball (5)
is retained. See FIGURE 90.

Figure 90
HGF Series Service Procedure

Install relief valve
cartridge and spring
assy. and hex plug

Place seals on por t
cover

CAUTION

40.

If required, place new O-Ring (7A)
onto hex plug (6A). Apply clean
grease to the O-Ring. Place the
rounded nose of the relief valve,
cartridge assembly (5A) into its
bore in the port cover (2). Place the
small end of coil spring (5B) on the
small pin on the back of the relief
valve cartridge assembly so it is
held in place. Install the hex plug
so the valve car tridge and coil
spring fit into the bore in the hex
plug. See FIGURE 8A. Tighten the
hex plug to 25-35 ft. lbs.
Apply clean grease to the three,
four or five O-Rings (4), and seal
ring (3) or white seal ring (3A) as
required. Place the new O-Rings
(4) and seal ring (3) or (3A) into
their proper location in the port
cover (2). See FIGURE 91.
CAUTION: If white seal ring (3A)
was removed from port cover (2),
a new white seal ring must be
assembled into the port cover.
The seal ring (3A) and seal ring (3)
are not interchangeable.

Install check ball

41A.If a check ball (52) was
removed from unit, place it in hole
in the port manifold (8).

Install port cover

42. Align a groove on the side of the
port cover (2) with the grooves on
the side of the port manifold (8)
and place the port cover (2) into
position. See FIGURE 92.

Install nuts

Figure 91

Figure 92

Figure 93

43. Install nuts (1) onto bolts (40).
Tighten each one gradually until
resistance is felt. Torque to 18-22
ft. lbs. (24-30 N m) in sequence
shown. See FIGURES 93 and
94. Torque plug (6) to 8-12 ft. lbs.
(11-16 N m). See FIGURE 95.

Figure 94
33

HGF Series Service Procedure

Install dirt and water
seal

44. Apply a small amount of clean
grease on the lip of the seal (39).
Install the seal onto the jacket
tube and input shaft/wheel tube.
See FIGURE 96.

Figure 95
Make final assembly
check and remove unit
from fixture

45. Make final check of the relative
groove positions on the side of the
unit using the component
alignment groove graphic on page
9B (fold-out) for comparison.
Disassemble and correct any
misassembly. Remove the four
nuts holding the unit to the fixture
and remove the unit. Make sure
shaft rotates by hand. See
FIGURE 97.

Figure 96
Assemble contact
brush and related parts

46. Place HGF unit on a clean
working surface. If required,
assemble spacer (51) [for 1 1/2
inch (38 mm) jacket tube only],
contact brush assembly (44)
washer (46) [for 1 3/4 inch (44
mm) jacket only] and screw and
lock washers (45). See FIGURES
98, 99, and 100. Check for the
required electrical continuity
(connection) from the horn cable
assembly (47) upper terminal to
the contact brush (44) terminal as
the input shaft/wheel tube is
rotated. There must not be any
electrical continuity (connection)
from the upper horn cable terminal
or contact brush terminal to any
other exposed part of the HGF
unit, including the body of the
contact brush.

Figure 97

Figure 98
HGF Series Service Procedure

Figure 99
TYPICAL
7/8" (22 mm) Input Shaft/Wheel Tube
1 1/2" (38 mm) Jacket Tube

New Horn Contact Design
7/8” (22 mm) Input Shaft/Wheel Tube
1 1/2” (38 mm) Jacket Tube

THIS COMPLETES THE ASSEMBLY OF HGF UNIT WITH THE
EXCEPTION OF WHEEL NUT (41), CONTACT BRUSH COVER
SEAL (48), CONTACT BRUSH COVER (49), AND RELATED
SCREW AND LOCK WASHERS (50) WHICH MUST AWAIT
INSTALLATION OF STEERING WHEEL AND ELECTRICAL
SOURCE CONNECTION. REF. FIGURES 99 AND 100.
CAUTION: IF THE INSTALLATION APPLICATION HAS A
JACKET TUBE (COLUMN) SUPPORT CLAMP, IT IS
EXTREMELY IMPORTANT THAT THE UPPER COVER AND
JACKET TUBE ASSEMBLY ALIGN WITH THIS CLAMP IN THE
FREE STATE. IF MISALIGNMENT IS EVIDENT, THE HGF
UNIT MUST BE SHIMMED AT THE MOUNTING SURFACE TO
ELIMINATE THIS MISALIGNMENT, OR DAMAGE TO THE HGF
UNIT MAY RESULT.

HGF Series Service Procedure

Hydraulic Fluid
Keep the steering system filled with one of the following:
• Automatic Transmission Fluid Type "F"
• Automatic Transmission Fluid Dexron II
• Hydraulic fluid as recommended by the vehicle manufacturer

WARNING: MAINTAIN THE PROPER FLUID LEVEL IN THE SYSTEM RESERVOIR. DO NOT MIX OIL TYPES.
A MIXTURE OF OIL TYPES OR AN UNAPPROVED OIL, COULD DETERIORATE THE SEALS, CAUSING
LEAKAGE THAT WOULD CREATE A LOSS OF POWER STEERING, COMPLETELY DRAIN OLD OIL FROM
THE SYSTEM BEFORE CHANGING TO ANOTHER FLUID. IT IS SUGGESTED ALSO THAT YOU FLUSH THE
SYSTEM WITH CLEAN OIL.

Filling and Air Bleeding the System
NOTE: For steps 1 and 2, do not turn the steering wheel.
1. Fill the reservoir nearly full. Crank the engine for 10 seconds without, if possible, allowing
the engine to start. If the engine does start, shut it off immediately. Do this procedure 3
times, each time checking and refilling the reservoir.
CAUTION: Do not allow fluid to drop significantly or to run out of the reservoir. This will
induce air into the system.
2. Start the engine and let it idle for 2 minutes. Shut the engine off and check the fluid level in
the reservoir.
NOTE: For step 3, have someone turn the steering wheel while you check the reservoir.
3. Start the engine. Steer the vehicle from full left to full right several times, all the while
adding fluid. When you are finished, add fluid to the fill line in reservoir.

HGF Series Service Procedure

Tips for Maintaining the Hydrostatic Steering System
Top up fluid level in reservoir as necessary.
Maintain correctly inflated tires.
Always use a puller to remove the steering wheel. Do not use a hammer, torch, or crow bar.
Investigate and correct immediately any play, rattle, shimmy, or other unusual occurrence in
the steering system.
Remove cause of steering column misalignment.
Encourage all drivers or operators to report any malfunction or accident that may have
damaged a steering system part.
Do not attempt to weld any broken steering component. Replace the component with original
equipment only.
Do not cold straighten, hot straighten, or bend any steering part.
Prevent dirt or other foreign matter from entering the hydraulic system. Clean off around filler
caps before checking oil level.
Investigate and correct any external leak in the steering system, no matter how minor the leak.
Comply with manufacturer's specifications for cleaning or replacing the filter.

WARNINGS for Proper Steering System Operation
WARNING: DO NOT WELD, BRAZE, OR SOLDER ANY STEERING SYSTEM COMPONENT.
WARNING: MAXIMUM OPERATING PRESSURE MUST NOT EXCEED VEHICLE MANUFACTURER'S
RECOMMENDED PUMP PRESSURE CAPACITY.
WARNING: ALWAYS CAREFULLY INSPECT ANY STEERING SYSTEM COMPONENT THAT MAY HAVE
BEEN STRUCK OR DAMAGED DURING OPERATION OR IN AN ACCIDENT. REPLACE ANY COMPONENT
THAT IS DAMAGED OR THAT IS QUESTIONABLE.

Ross extends close technical cooperation and assistance. If steering problems occur which you cannot solve, please
contact our Ross Field Service Department. Our phone number and address are on the back cover of this manual

HGF Series Service Procedure

Notes

HGF Series Service Procedure

Ross Operations
2745 Snapps Ferry Road
Greeneville, TN 37745 USA
Phone:
(423) 639-8151
Fax:
(423) 787-2418

b&b #962252—25

11/96

Source Exif Data:

File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.3
Linearized                      : Yes
Create Date                     : 1999:08:25 09:59:02
Producer                        : Acrobat Distiller 3.0 for Windows
Author                          : Pump Motor Division
Creator                         : QuarkXPress  4.04: LaserWriter 8 8.6
Title                           : Hydraguide HGF Series Hydrostatic Steering System
Modify Date                     : 2000:07:30 16:53:56-04:00
Subject                         : Service Manual
Page Count                      : 46
Page Mode                       : UseOutlines
Page Layout                     : SinglePage

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Hydraguide HGF Series Hydrostatic Steering System 318, 322, 330, 332, 420, 430 Parker Service (SM2753) 318 322 330 332 420 Service(SM2753)

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