BRAKE SYSTEM

S6.00-7.00XL (S135-155XL, S155XLS,

S135-155XL

2

) [B024, C024]

PART NO. 897393

1800 SRM 452

SAFETY PRECAUTIONS

MAINTENANCE AND REPAIR

• When lifting parts or assemblies, make sure all slings, chains, or cables are correctly

fastened, and that the load being lifted is balanced. Make sure the crane, cables, and
chains have the capacity to support the weight of the load.

• Do not lift heavy parts by hand, use a lifting mechanism.

• Wear safety glasses.

• DISCONNECT THE BATTERY CONNECTOR before doing any maintenance or repair

on electric lift trucks. Disconnect the battery ground cable on internal combustion lift
trucks.

• Always use correct blocks to prevent the unit from rolling or falling. See HOW TO PUT

THE LIFT TRUCK ON BLOCKS in the Operating Manual or the Periodic Mainte-
nance section.

• Keep the unit clean and the working area clean and orderly.

• Use the correct tools for the job.

• Keep the tools clean and in good condition.

• Always use HYSTER APPROVED parts when making repairs. Replacement parts

must meet or exceed the specifications of the original equipment manufacturer.

• Make sure all nuts, bolts, snap rings, and other fastening devices are removed before

using force to remove parts.

• Always fasten a DO NOT OPERATE tag to the controls of the unit when making repairs,

or if the unit needs repairs.

• Be sure to follow the WARNING and CAUTION notes in the instructions.

• Gasoline, Liquid Petroleum Gas (LPG), Compressed Natural Gas (CNG), and Diesel fuel

are flammable. Be sure to follow the necessary safety precautions when handling these
fuels and when working on these fuel systems.

• Batteries generate flammable gas when they are being charged. Keep fire and sparks

away from the area. Make sure the area is well ventilated.

NOTE:

The following symbols and words indicate safety information in this

manual:

WARNING

Indicates a condition that can cause immediate death or injury!

CAUTION

Indicates a condition that can cause property damage!

Brake System

Table of Contents

TABLE OF CONTENTS

General ...............................................................................................................................................................

1

Description and Operation ................................................................................................................................

1

Brake Booster and Master Cylinder .............................................................................................................

1

Service Brake Assembly ................................................................................................................................

3

Parking Brake................................................................................................................................................

3

Brake Shoe Assemblies Repair .........................................................................................................................

4

Remove and Disassemble ..............................................................................................................................

4

Clean ..............................................................................................................................................................

5

Inspect ............................................................................................................................................................

5

Assemble and Install .....................................................................................................................................

5

Master Cylinder Repair .....................................................................................................................................

6

Remove ...........................................................................................................................................................

6

Disassemble ...................................................................................................................................................

6

Clean and Inspect ..........................................................................................................................................

7

Assemble ........................................................................................................................................................

7

Install .............................................................................................................................................................

8

Brake Booster Repair.........................................................................................................................................

8

Remove ...........................................................................................................................................................

8

Disassemble ...................................................................................................................................................

8

Clean and Inspect ..........................................................................................................................................

8

Assemble ........................................................................................................................................................

9

Install .............................................................................................................................................................

10

Brake System Air Removal ...............................................................................................................................

10

Brake Pedal Adjustment ...................................................................................................................................

10

Brake Shoes Adjustment ...................................................................................................................................

11

Parking Brake Adjustment ...............................................................................................................................

11

Brake Booster Relief Valve Check.....................................................................................................................

11

Troubleshooting..................................................................................................................................................

12

This section is for the following models:

S6.00-7.00XL (S135-155XL, S155XLS, S135-155XL

2

) [B024, C024]

©2004 HYSTER COMPANY

i

"THE

QUALITY

KEEPERS"

HYSTER

APPROVED

PARTS

1800 SRM 452

Description and Operation

General

This section has a description and the repair proce-
dures for the parts of the brake system. These parts
include the brake booster, master cylinder (see Fig-
ure 1), and brake shoe assemblies.

The brake system on this series of lift trucks uses
a hydraulic actuator (brake booster) to actuate the
master cylinder. The operation of the brake booster
decreases the foot effort necessary to apply the
brakes. The oil flow from the outlet of the steering
control unit is used to operate the brake booster.

1.

BRAKE BOOSTER

2.

INLET FROM STEERING CONTROL UNIT

3.

OUTLET TO HYDRAULIC TANK

4.

MASTER CYLINDER

5.

INLET FROM RESERVOIR

6.

OUTLET TO WHEEL CYLINDERS

Figure 1. Brake Booster and Master Cylinder

Description and Operation

The brake system consists of service brakes and the
parking brake. The service brakes have the brake
pedal, booster and master cylinder, and a brake as-
sembly at each drive wheel. The parking brake has
the hand lever assembly, cables to each service brake
assembly, and a lever in the service brake assembly
to mechanically move the brake shoes.

The operator pushes the brake pedal to apply the
brake. This action pushes the push rod of the booster
to move the plunger. When the plunger moves, it
moves the piston. When the piston moves, it allows
the pressure from the steering pump to enter the
booster and help move the piston.

As the piston

moves, it moves the piston rod to move the piston of
the master cylinder. Brake fluid is forced through

the brake lines to the wheel cylinders.

The fluid

forces the pistons of the wheel cylinders to move the
brake shoes against the brake drums to stop the lift
truck.

When the operator releases the latch and pulls the
parking brake lever, the cables move the lever to
move the brake shoes against the brake drum to
keep the lift truck from moving.

BRAKE BOOSTER AND MASTER
CYLINDER

The operation of the brake booster and master cylin-
der is shown and described in Figure 2.

1

Description and Operation

1800 SRM 452

A. BRAKES NOT APPLIED

HYDRAULIC OIL FLOWS FROM STEERING CONTROL UNIT TO INLET OF BRAKE VALVE. HYDRAULIC
OIL FLOWS FREELY BETWEEN PLUNGER AND PISTON AND RETURNS TO HYDRAULIC TANK FROM
OUTLET.

B. BRAKES APPLIED

WHEN THE BRAKES ARE APPLIED AND ENGINE IS NOT RUNNING, PLUNGER PUSHES AGAINST
PISTON. PISTON AND PISTON ROD PUSH AGAINST PISTON IN MASTER CYLINDER TO ACTUATE
BRAKES.
WHEN THE ENGINE IS RUNNING, HYDRAULIC OIL FLOWS THROUGH BRAKE VALVE.
MOVEMENT OF PLUNGER RESTRICTS FLOW OF OIL BETWEEN PLUNGER AND PISTON. HYDRAULIC
PRESSURE BEHIND PISTON INCREASES AND PUSHES ON PISTON AND PISTON ROD TO MOVE
PISTON IN MASTER CYLINDER. OIL PRESSURE BEHIND PISTON DECREASES THE EFFORT AT BRAKE
PEDAL TO APPLY BRAKES. AS PISTON FOR MASTER CYLINDER MOVES, BRAKE FLUID FLOWS FROM
OUTLET TO WHEEL CYLINDERS. RELIEF VALVE PROVIDES A 2300 kPa (332 psi) LIMIT TO HYDRAULIC
PRESSURE IN BRAKE VALVE.

1.

BRAKE VALVE (BOOSTER)

2.

INLET

3.

PLUNGER

4.

PISTON (BRAKE VALVE)

5.

PISTON ROD

6.

OUTLET TO HYDRAULIC TANK

7.

MASTER CYLINDER

8.

PISTON (MASTER CYLINDER)

9.

OUTLET TO WHEEL
CYLINDERS

10. INLET FROM BRAKE

RESERVOIR

11. RELIEF VALVE

Figure 2. Brake Booster and Master Cylinder Operation

2

1800 SRM 452

Description and Operation

SERVICE BRAKE ASSEMBLY

A service brake assembly is used at each end of the
drive axle housing. See Figure 3. Each service brake
assembly has a wheel cylinder at the top of each
back plate. A shoe guide and guide springs keep the
shoes against the back plate. Return springs hold
the brake shoes tight against the wheel cylinder and
the adjuster mechanism.

1.

BACK PLATE

2.

SHOE GUIDE

3.

WHEEL CYLINDER

4.

RETURN SPRING

5.

GUIDE SPRING

6.

BRAKE SHOE

7.

AUTOMATIC
ADJUSTER
MECHANISM

8.

BRAKE LEVER

9.

BRAKE LINK

Figure 3. Service Brake Assembly

When the piston of the wheel cylinder is moved by
fluid pressure from the master cylinder, the piston
moves the brake shoes to contact the drum. The pri-
mary shoe starts to turn with the brake drum. This
action pushes the secondary shoe tight against the
brake drum. This servo action increases the force ap-
plied to the brake drums.

The automatic adjuster mechanism turns the ad-
juster wheels to adjust the clearance between the
brake shoes and the drum. The adjuster mechanism
operates when the lift truck is traveling in forward
or reverse. When the brakes are applied, the brake
shoes move toward the brake drum. When the bot-
tom of a brake shoe moves away from the adjuster

mechanism, the adjuster wheel moves away from
the adjuster plate. When there is clearance between
the shoe and drum, the adjuster plate can move and
engage the next tooth of the adjuster wheel. The
springs on the adjuster plate cause the adjuster
plate to rotate when the brake pressure is released.

PARKING BRAKE

The parking brake uses the service brake shoes. See
Figure 4. Additional linkage pushes the shoes apart
when the hand lever pulls the cables. On units with a
powershift transmission and a MONOTROL

®

pedal,

the hand lever also operates a switch to allow the key
switch to energize the starting circuit for the engine.

1.

HAND LEVER

2.

CABLES TO BRAKE SHOES

3.

SWITCH

Figure 4. Parking Brake Assembly

3

Brake Shoe Assemblies Repair

1800 SRM 452

When the parking brake is applied, the switch de-en-
ergizes the circuit for the MONOTROL pedal and the
Forward and Reverse solenoids. This action puts the

transmission in NEUTRAL. The starting circuit for
the engine is energized when the parking brake is
applied.

Brake Shoe Assemblies Repair

REMOVE AND DISASSEMBLE

WARNING

Brake linings can contain dangerous fibers.
Breathing the dust from these brake linings
is a cancer or lung disease hazard.

Do not

create dust!

Do not clean brake parts with

compressed air or by brushing. Use vacuum
equipment approved for brake dust or follow
the cleaning procedure in this section. When
the brake drums are removed, do not create
dust.

Do not sand, grind, chisel, hammer, or change
linings in any way that will create dust. Any
changes to brake linings must be done in a re-
stricted area with special ventilation. Protec-
tive clothing and a respirator must be used.

1.

Tilt the upright back and put blocks under the
outer upright weldments. Tilt the upright for-
ward to raise the tires from the floor.

2.

The wheels, hub, and brake drum can be re-
moved as an assembly. See Figure 5.

3.

Remove the capscrews that hold the axle shaft to
the hub. Remove the axle shaft.

4.

Remove the seal from the hub. Remove the nuts
for the bearings from the axle housing. Slide the
wheel, hub and brake drum from the axle hous-
ing.

5.

Use spring pliers to remove the shoe return
springs. See Figure 3. Remove the clips at the
backplate for the guide springs.

Remove the

guide springs.

6.

Disconnect the parking brake cable from the
parking brake lever. See Figure 3. Remove the
brake shoes.

7.

If necessary, the adjuster mechanism and wheel
cylinder can be removed from the backplate. See
Figure 3. The backplate can be removed from the
axle housing.

1.

AXLE HOUSING

2.

AXLE SHAFT

3.

HUB

4.

BEARING CUP

5.

BEARING CONE

6.

BRAKE DRUM

7.

SEAL

8.

LOCK NUT

9.

LOCKWASHER

10. ADJUSTMENT NUT
11. WHEEL NUT
12. BRAKE ASSEMBLY
13. WEAR SLEEVE
14. GASKET
15. TAPERED

CAPSCREW

16. WHEEL

Figure 5. Drive Axle and Brake Assembly

4

1800 SRM 452

Brake Shoe Assemblies Repair

CLEAN

WARNING

Brake linings can contain dangerous fibers.
Breathing the dust from these brake linings
is a cancer or lung disease hazard.

Do not

create dust!

Do not clean brake parts with

compressed air or by brushing. Use vacuum
equipment approved for brake dust or follow
the cleaning procedure in this section. When
the brake drums are removed, do not create
dust.

Do not sand, grind, chisel, hammer, or change
linings in any way that will create dust. Any
changes to brake linings must be done in a re-
stricted area with special ventilation. Protec-
tive clothing and a respirator must be used.

1.

Do not release brake lining dust into the air when
the brake drum is removed.

2.

Use a solvent to wet the brake lining dust on the
parts of the brake. If a solvent spray is used, do
not create dust with the spray.

3.

When the dust is wet, clean the parts. Put any
cloth or towels in a plastic bag or an airtight con-
tainer while they are still wet. Put an DANGER-
OUS FIBERS warning label on the plastic bag or
airtight container.

4.

Any cleaning cloths that will be washed must be
cleaned so that the fibers are not released into
the air.

INSPECT

CAUTION

Do not use solvent to clean the wheel cylinder.
Do not get oil or grease in the brake fluid or on
the brake linings. Use a brake cleaning fluid to
clean the linings and the brake hydraulic parts.

1.

Clean all metal parts except the linings and the
wheel cylinder with solvent.

2.

Check the bore of the wheel cylinder for corro-
sion, pitting or scratches.

Replace the wheel

cylinder if there is any damage.

3.

Check the return springs for defects. Inspect the
backplate for wear where the brake shoes touch
the backplate.

4.

Inspect the brake shoes for cracks or damage. If
the linings or shoes are worn or damaged, replace
the brake shoes. It is recommended that if one
brake shoe is replaced, both brake shoes on the
wheel should be replaced.

NOTE: If the brake drums require turning on a
lathe, do not remove more than 1.5 mm (0.060 in.)
from the diameter. The maximum inside diameter
of the brake drum, including wear, is 316.82 mm
(12.473 in.).

If the diameter is larger than this,

replace the brake drum.

5.

Inspect the brake drum for deep grooves or other
damage on the surface for the brake shoes. Use
sandpaper to smooth the grooves on the brake
drum surface.

ASSEMBLE AND INSTALL

1.

Install the wheel cylinder and shoe guide on the
backplate. See Figure 3. Install the adjuster
mechanism on the backplate. Use the following
procedure to adjust the adjuster mechanism:

a. Check the clearance between the adjuster

plate and the adjuster wheels. See Figure 6.
Use shims between the adjuster wheels and
the housing until the clearance is 1.04 to
1.34 mm (0.041 to 0.053 in.). This adjust-
ment is important for the correct operation
of the automatic brake adjuster.

1.

ADJUSTER WHEEL

2.

ADJUSTER PLATE

3.

SHIMS

Figure 6. Automatic Adjuster Mechanism

5

Master Cylinder Repair

1800 SRM 452

NOTE:

If the lift truck does not have frequent hard

braking applications and the position of the brake
pedal is low, the brakes are not adjusting enough.
Change the shims at the adjuster wheel so that there
is a clearance of 1.50 mm (0.059 in.) at the arrows
(see Figure 6).

NOTE:

If the lift truck has frequent hard braking ap-

plications and the brakes are too tight, the brakes
are not adjusting correctly. Change the shims at the
adjuster wheel, so there is a clearance of 1.80 mm
(0.071 in.) at the arrows (see Figure 6).

2.

Install the backplate on the axle housing. Install
the tapered sleeves and the nuts. Tighten the
nuts in the cross pattern to 55 to 80 N•m (41 to
59 lbf ft), then tighten the nuts in the same cross
pattern to 110 to 125 N•m (81 to 92 lbf ft).

3.

Install the lever for the parking brake on the
brake shoe. See Figure 3. Install the brake shoe.
Install the parking brake link. Connect the park-
ing brake cable to the lever.

4.

Install the guide springs and install the clips on
the back of the brake plate. See Figure 3. Install
the shoe return springs.

5.

If removed, install the hub, brake drum and
wheels on the hub. See Figure 5. Tighten the
nuts for the brake drum and wheels to 610 to
680 N•m (450 to 500 lbf ft).

6.

Lubricate the inner wheel bearing with grease,
then install the inner seal in the hub. See Fig-
ure 5.

CAUTION

Do not damage the seal when installing the
wheel and hub assembly.

7.

Slide the wheel and hub assembly on the axle
housing. See Figure 5. Lubricate the outer wheel
bearing with grease and install the bearing on
the axle housing.

8.

Install the bearing adjusting nut. See Figure 5.
Tighten the nut to 200 N•m (150 lbf ft) while
turning the hub. Loosen the nut to less than
27 N•m (20 lbf ft). Tighten the nut to 35 N•m
(26 lbf ft). Lock the adjusting nut at this position
or tighten the nut to the first position where the
lockwasher fits. Install the lock nut and tighten
it to 135 N•m (100 lbf ft).

9.

Use a sealant on the flange of the oil seal and
install the outer seal in the hub. See Figure 5.
Use a sealant on the axle flange and install the
axle shaft. Tighten the capscrews to 165 N•m
(122 lbf ft). Check the differential oil level and
fill as described in the section Periodic Main-
tenance 8000 SRM 393.

10. Fill the brake reservoir and remove the air from

the brake system and adjust the brakes as spec-
ified in Brake System Air Removal, Brake Pedal
Adjustment, and Brake Shoes Adjustment in this
SRM.

Master Cylinder Repair

NOTE: It is recommended that when the master
cylinder is repaired or replaced, replace the brake
booster seal shown in Figure 9.

REMOVE

1.

Disconnect the brake line at the master cylinder.
Cover the end of the brake line. Disconnect the
wires at the brake switch. Disconnect the hose
from the reservoir. Put a plug in the end of the
hose.

2.

Remove the capscrews that hold the master
cylinder to the brake booster.

DISASSEMBLE

WARNING

The piston has a compressed spring behind it.
Remove the piston carefully. Make sure to hold
the spring in position so it cannot cause dam-
age or injury to someone.

CAUTION

Use a cleaning fluid made for brake parts when
cleaning the master cylinder.

1.

Remove the retaining ring from the end of the
master cylinder. See Figure 7. Carefully remove
the piston and spring from the bore.

6

1800 SRM 452

Master Cylinder Repair

1.

HOUSING

2.

RETAINING RING

3.

SEAL

4.

PISTON

5.

SPRING

6.

CUP WASHER

7.

SEAL SUPPORT WASHER

8.

CHECK VALVE

9.

SPRING

10. FITTING

Figure 7. Master Cylinder

2.

Remove the seals from the piston.

3.

Remove the fitting, check valve, and spring.

CLEAN AND INSPECT

CAUTION

DO NOT use an oil solvent to clean the master
cylinder, wheel cylinder, or brake linings. Use
a solvent approved for cleaning brake parts.
Do not permit oil or grease in the brake fluid
or on the linings.

Inspect the bore of the master cylinder for holes or
scratches. Replace the master cylinder assembly if
there is damage.

ASSEMBLE

NOTE:

Lubricate the parts of the master cylinder

with clean brake fluid.

1.

Install the seals and cup washers on the piston.
See Figure 7. Install the spring and the piston
in the master cylinder. Be careful not to cut the
seal when installing it in the bore.

2.

Install the retaining ring for the piston.

3.

Install the spring, check valve, and fitting.

7

Brake Booster Repair

1800 SRM 452

INSTALL

1.

Put the master cylinder in position on the brake
booster and install the capscrews for the master
cylinder.

2.

Connect the brake lines and wires. Connect the
hose to the brake fluid reservoir. Fill the reser-
voir and remove the air from the brake system as
described in Brake System Air Removal in this
SRM.

Brake Booster Repair

REMOVE

1.

Disconnect the brake pedal from the brake
booster at the push rod.

2.

Remove the air cleaner, battery and battery tray.

3.

Disconnect the hydraulic lines at the brake
booster. Put caps on the open lines.

4.

Disconnect the brake lines and wires at the mas-
ter cylinder. See Figure 8. Disconnect the hose
from the reservoir at the master cylinder. Put a
plug in the end of the hose.

5.

Remove the capscrews that hold the brake
booster to the bracket. Remove the brake booster
and master cylinder as an assembly.

1.

BRAKE BOOSTER

2.

INLET FROM STEERING CONTROL UNIT

3.

OUTLET TO HYDRAULIC TANK

4.

MASTER CYLINDER

5.

INLET FROM RESERVOIR

6.

OUTLET TO WHEEL CYLINDERS

Figure 8. Brake Booster and Master Cylinder

DISASSEMBLE

1.

Remove the master cylinder from the brake
booster.

2.

Remove the dust cover and push rod. See Fig-
ure 9.

3.

Remove the retaining ring and washer for the
plunger. Remove the plunger from the retainer.

WARNING

The retainer has a compressed spring behind
it. Make sure to hold the spring in position so
that it cannot cause damage or injury to some-
one.

4.

Remove the retainer from the housing.

5.

Remove the piston, spring, and piston rod from
the housing.

6.

Remove the seals and O-rings from the parts of
the brake booster.

7.

If necessary, remove the parts of the relief valve
from the housing.

CLEAN AND INSPECT

WARNING

Cleaning solvents can be flammable and toxic,
and can cause skin irritation.

When using

cleaning solvents, always follow the recom-
mendations of the manufacturer.

Clean the parts of the brake booster with solvent.
Check the surface of the machined parts for wear and
damage.

8

1800 SRM 452

Brake Booster Repair

1.

PUSH ROD

2.

DUST COVER

3.

RETAINING RING

4.

WASHER

5.

RETAINER

6.

PLUNGER

7.

BOOSTER SEAL

8.

PISTON

9.

PISTON SEAL

10. PISTON ROD
11. ROD SEAL
12. SLEEVE
13. O-RING
14. SCREW
15. RELIEF PISTON
16. SPRING

17. GUIDE
18. SHIM
19. PLUG
20. SNAP RING
21. SPRING
22. HOUSING
23. RELIEF VALVE

Figure 9. Brake Booster

ASSEMBLE

NOTE: Use new parts from the repair kit. Lubricate
the parts with hydraulic oil during assembly. Make
sure the parts are clean.

CAUTION

Do not let brake fluid touch any of the parts of
the brake booster. The brake fluid can damage
the seals in the brake booster.

1.

Assemble the parts for the relief valve. Make
sure all of parts are in their original positions.
See Figure 9.

2.

Install the seals for the piston rod, plunger and
the piston. See Figure 9.

3.

Install the piston rod, piston, and spring in the
housing. Install the retainer and O-ring in the
housing. Tighten the retainer to 210 to 290 N•m
(155 to 215 lbf ft).

4.

Install the plunger in the retainer. Install the
washer and the retaining ring.

5.

Install the dust cover and the push rod.

9

Brake Pedal Adjustment

1800 SRM 452

INSTALL

1.

Install the master cylinder on the brake booster.
Install the brake booster on the bracket. See Fig-
ure 8.

2.

Connect the hydraulic lines to the brake booster.
Connect the brake lines and wires to the master
cylinder. Connect the hose from the reservoir to
the master cylinder.

3.

Connect the push rod to the crank and the brake
pedal. Install the pin for the push rod.

4.

Remove the air from the brake system and adjust
the brake linkage as described in Brake System
Air Removal and Brake Pedal Adjustment in this
SRM.

Brake System Air Removal

The air must be removed from the brake fluid. Fill
the reservoir of the master cylinder with brake fluid.
Put one end of a rubber hose on the special fitting of
the wheel cylinder. Put the other end of the hose in a
container with brake fluid. Loosen the special fitting.
Push slowly on the brake pedal. Close the fitting at
the wheel cylinder. Repeat the procedure until no air

bubbles are seen in the container. Check the fluid
level in the master cylinder. Keep the master cylin-
der full of brake fluid during these procedures. Use
the procedures described for the wheel cylinders to
remove air from the relief tube at the master cylin-
der. Use the fitting at the line connector on the relief
valve.

Brake Pedal Adjustment

NOTE:

The adjustment procedures for the inching

pedal are in the section Two-Speed Powershift
Transmission 1300 SRM 325.

1.

Adjust the height of the brake pedal above the
floor plate as shown in Figure 10. Use the stop

capscrew and lock nut behind the pedal to adjust
the height.

2.

Adjust the linkage rod for the brake booster so
that there is 5.5 mm (0.22 in.) of free travel in
the brake pedal.

Figure 10. Brake Pedal Adjustment

10

1800 SRM 452

Brake Booster Relief Valve Check

Legend for Figure 10

A. 1.3 mm (0.05 in.) ONE HALF TURN

1.

BRAKE PEDAL

2.

STOP CAPSCREW

3.

LOCK NUT

4.

LINKAGE ROD

5.

MASTER CYLINDER

Brake Shoes Adjustment

NOTE: If the lift truck does not have frequent hard
braking applications and the position of the brake
pedal is low, the brakes are not adjusting enough.
Change the shims at the adjuster wheel so that there
is a clearance of 0.94 mm (0.037 in.) at the arrows.
See Figure 6.

NOTE: If the lift truck has frequent hard braking
applications and the brakes are too tight, the brakes
are not adjusting correctly. Change the shims at the
adjuster wheel so that there is a clearance of 1.40 mm
(0.055 in.) at the arrows. See Figure 6.

The brake shoes will adjust automatically by apply-
ing the brake pedal while traveling in forward or re-
verse. To manually adjust the brakes, it is necessary
to turn the adjuster wheels. See Figure 11. Remove
the rubber plugs in the adjustment slots located in
the rear of the backing plate. Put a small screw-
driver through the slot in the backplate. Push the
adjuster plate away from the adjuster wheel and turn
the adjuster wheel until the brake shoe just touches
the brake drum. Turn the other adjuster wheel un-
til the brake shoe just touches the brake drum. Ad-
just the brake shoes for the other wheel using the
same method. Make sure to install the plugs after
the adjustment is complete. Remove the blocks and
operate the lift truck in the forward and reverse di-
rections. Make 10 stops in each direction using the
brakes. This action will adjust the brakes automati-
cally.

1.

BACK PLATE

2.

SHOE GUIDE

3.

WHEEL CYLINDER

4.

RETURN SPRING

5.

GUIDE SPRING

6.

BRAKE SHOE

7.

AUTOMATIC
ADJUSTER
MECHANISM

8.

BRAKE LEVER

9.

BRAKE LINK

Figure 11. Service Brake Assembly

Parking Brake Adjustment

Turn the knob on the hand lever to adjust the park-
ing brake. The brake must hold the lift truck with a
capacity load on a 15% grade.

If the lift truck has a powershift transmission and a
MONOTROL pedal, make sure the switch is actuated
by the hand lever when the parking brake is applied.

Brake Booster Relief Valve Check

The relief valve is adjusted at the factory and is not
normally adjustable. Shims can be added or removed

between the spring and the valve stem. The correct
relief pressure is 2275 kPa (330 psi).

11

Troubleshooting

1800 SRM 452

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

The brakes do not correctly
stop the lift truck.

Air in the brake system.

Repair system to prevent air enter-
ing. Remove air from the system.

The mount for the master cylinder is
loose.

Tighten fasteners.

The brake shoes are worn or dam-
aged.

Install new brake shoes.

The linings are too hard.

Install new correct lining.

A hub is cracked or has other dam-
age.

Install new hub.

A backplate is damaged.

Install new backplate.

A wheel cylinder is leaking or does
not operate correctly.

Repair or install new wheel cylinder.
Remove air from the system.

The brake linings do not fit the hubs.

Install correct linings. Machine the
shoe surface of the hubs.

The master cylinder is damaged.

Install new master cylinder. Remove
air from the system.

Water or oil is on the brake linings.

Clean or install new linings.

The brake booster does not operate
correctly.

Repair brake booster.

The seal in the brake booster is dam-
aged.

Repair brake booster.

One brake does not release.

A brake shoe is damaged.

Install new brake shoes.

A return spring is wrong.

Install new correct spring.

The brake lines have a restriction.

Remove restriction or install new
lines. Remove air from the system.

A parking brake cable is damaged or
needs adjustment.

Adjust cable or install new cable.

The wheel cylinder is damaged.

Repair or install new wheel cylinder.
Remove air from the system.

The backplate is worn or damaged.

Install new backplate.

12

1800 SRM 452

Troubleshooting

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

The brakes make too much
noise.

Dirt, oil, water, or brake fluid is on
the linings.

Clean or install new linings.

The brake linings are worn.

Install new linings.

A brake shoe is worn or damaged.

Install new brake shoe(s).

The brakes do not operate
equally.

Oil or brake fluid is on the linings.

Repair leak. Install new linings.

The linings are worn or hard.

Install new linings.

A wheel cylinder is leaking.

Repair or install new wheel cylinder.
Remove air from the system.

The brake linings are not correctly
installed.

Install brake linings correctly.

The backplate or brake shoes are
damaged.

Install new parts.

The brake drums are not round.

Check to make sure there is adequate
material to permit machining. Ma-
chine the brake shoe area of brake
drums to make them round or install
new brake drums.

The brake shoes are adjusted too
tight.

Adjust the brakes.

Check self-ad-

justers.

Both brakes do not release.

The parking brake is not released.

Release parking brake.

The parking brake cables need ad-
justment.

Adjust or install new cables.

There is not enough clearance at the
end of the push rod in the master
cylinder.

Adjust the clearance between the
push rod and the piston.

The master cylinder is damaged.

Install new master cylinder. Remove
air from the system.

The brake shoes are adjusted too
tight.

Check operation of self-adjusters.
Adjust brakes.

13

Troubleshooting

1800 SRM 452

PROBLEM

POSSIBLE CAUSE

PROCEDURE OR ACTION

The brake pedal travels too
far.

Air in the brake system.

Remove air from the system. Check
for leaks.

Brake fluid level low. The brake sys-
tem has a leak.

Fill brake fluid reservoir to the cor-
rect level. Repair leak. Remove air
from the system.

The brake shoes are not adjusted cor-
rectly.

Check operation of self-adjusters.
Adjust brakes.

The brake linings are worn.

Install new linings.

One of the dual brake circuits is not
operating.

Repair brake circuit that has failed.

There is too much clearance at the
end of the push rod in the master
cylinder.

Adjust the clearance between the
push rod and the piston.

The master cylinder is worn or dam-
aged.

Repair or install new master cylin-
der. Remove air from the system.

The parking brake will not
hold the lift truck.

Parking brake not adjusted correctly.

Use adjustment knob on parking
brake lever to adjust holding force.
See adjustment procedure for correct
specifications.

Oil, water, or brake fluid is on the lin-
ings.

Clean or install new linings.

The parking brake cables need ad-
justment, lubrication, or have dam-
age.

Install new parts. Lubricate and ad-
just cables.

The parking brake will not
release.

The parking brake lever is adjusted
too tightly.

Adjust parking brake.

See adjust-

ment procedure for correct specifica-
tions.

The parking brake cables need ad-
justment, lubrication, or have dam-
age.

Install new parts. Lubricate and ad-
just cables.

14

TECHNICAL PUBLICATIONS

1800 SRM 452

2/04 (9/03)(3/89) Printed in United Kingdom