9.
WHEEL BRAKE
9.1 STRUCTURE AND FUNCTION
9.1.1 WHEEL BRAKE
WHEEL BRAKE STRUCTURE
5 (*1)
*1
A
1 2
Item Unit Wheel Brake
Type – Front wheel internal expanding hydraulic type
Structure – Duo servo
Brake Drum Inner Diameter in. (mm) 12.2 (310.0)
Lining Material – Resin molded (Adhesive type)
Width in. (mm) 2.36 (60.0)
Thickness in. (mm) .224 (5.7)
Wheel Cylinder Inner Diameter in. (mm) 1.25 (28.58)
9-3
9. WHEEL BRAKE
9.1.2 BRAKE BOOSTER
BRAKE BOOSTER STRUCTURE
13 12 5 A 6 7
2 1 11 10 B 3 4 9 8
1. Reservoir 6. Reaction Piston 11. Hydraulic Tank
2. Wheel Cylinder 7. Push Rod 12. Piston
3. Pump 8. Spring 13. Return Spring
4. Flow Divider 9. Control Valve
5. Booster Piston 10. Valve sear
1. A certain amount of oil is supplied to the brake booster from the pump (3) through the flow divider (4). The oil
enters to the power chamber (A) inside the brake booster and flows to the hydraulic tank (11) via the hole of the
booster piston (5) after passing through the space (B) being formed between the control valve (9) and valve
(10) respectively.
2. When the brake booster is off, the oil sees no resistance in passing through inside the booster including
chamber (B), which makes no hydraulic pressure inside the booster.
3. When the brake pedal is pressed down, the reaction piston (6) is pushed out to the left by the push rod so as to
pressurize space (B).
4. With space (B) under pressure, the oil encounters resistance when passing through the space (B), which
should increase the hydraulic pressure in the power chamber (A).
5. With such an increase in hydraulic pressure in the power chamber (A), the hydraulic pressure presses to the
right side of the booster piston (5) so as to push the return spring (13) away and move the piston (12) to the
left.
6. Also, the hydraulic pressure in the power chamber (A) should push the rear piston (6) back to the right
(generating an anti-hydraulic force), which should balance with the brake pedal control force.
7. Therefore, it becomes the receiving pressure area or servo of the booster piston (5) and the reaction piston (6).
However, when the force to push the valve seat (10) back to the right due to the increased hydraulic pressure
in the power chamber (A) is stronger than the spring (8), the space (B) cannot be compressed and the increase
in pressure in the power chamber (A) should stop.
8. In case of a problem at the pump or engine stall, the reaction piston (6), the booster piston (5) and the piston
(12) should be mechanically engaged, which would enable you to operate manually.
9-4
9. WHEEL BRAKE
9.1.3 BRAKE MASTER CYLINDER
MASTER CYLIINDER STRUCTURE
11
9 10
8
2 1
4 12
13
5
17
6 14
7
15
16
1. Cylinder 8. Bleeder Valve
2. Piston Assembly 9. Bleeder Cap
3. Snap Ring 10. Valve Spring
4. Boot 11. Seat
5. Push Rod 12. Valve Rubber
6. Nut 13. Gasket
7. Yoke 14. Bolt
Repair
Standard Size
Check Item Limit Remedy Ref. No.
in. (mm)
in. (mm)
Clearance between Cylinder .0008 - .0040 Replacement
.006 (0.15) 1.2
and Piston (0.020 - 0.105) (Cylinder Assembly)
Primary: approx. .04 (1.0) Replacement
Tightening Clearance of Cup .016 (0.4) 2
Secondary: approx. .047 (1.2) (Cylinder Assembly)
Free Length for Spring 3.1 (78.8) 2.76 (70) Replacement 2
NOTE: The numbers shown in the Ref. No. on the right refer to those in the diagram of the component parts.
9-5
9. WHEEL BRAKE
9.2 PERIODIC INSPECTION AND MAINTENANCE CHECK POINTS
9.2.1 TRAVELING BRAKE
1. Brake pedal
a. Pedal height (stroke)
2.0 - 3.0 ton 2.16 - 2.95 in. (55 - 75 mm)
3.5 ton 1.77 - 2.56 in. (45 - 65 mm)
b. Play
Standard model 0 - .157 in. (0 - 4 mm)
137 mm
2. Braking efficiency
Select dry and even surface road, drive at full speed and
stop abruptly to check the following:
a. Pulling of steering wheel
b. Dragging of brakes
c. Abnormal noise
d. Stopping distance
Unloaded within 14.7 ft (4.5 m) (at max. speed)
Loaded within 6.6 ft (2.0 m) (at 10 km/h)
9.2.2 PARKING BRAKES
1. Parking brake lever
Lever control force Standard brake:
33 - 44 lb/f (147 - 196 Nm) (15 - 20 kgm)
Power brake: 55 - 66 lb/f
(245 - 294 Nm) (25 - 30 kgm)
2. Braking force
Check if the truck can maintain braking on the following
slope:
Unloaded slope of 11.2 degrees and over
Loaded slope of 8.5 degrees and over
9.2.3 ROD LINK, CABLE
1. Scratches, looseness or play
2. Breakage of cotter pin
9.2.4 BRAKE PIPING
1. Visual check on piping, hoses and joints
2. Scratches
3. Oil leakage
4. Evidence of interference or contact
5. Deterioration of hose
6. Loosening of mounting bolt
9.2.5 PARKING BRAKE DRUM, LINING
Common with the travel brake drum, lining. See “Brake Booster” on page 9-7.
9-6
9. WHEEL BRAKE
9.2.6 OIL BRAKE
1. Master cylinder and wheel cylinder
Check the following by operating the brake pedal
a. Pressure (feel) when pedal depressed
b. Fluctuation of pressure or pedal height
c. Fluctuation of pedal position when maintaining pedal pressure
d. Return of the pedal when releasing the pedal
NOTE: If you feel a change while pressing the pedal with no
oil leakage, the brake valve is defective.
2. Brake reservoir
a. Oil level amount
Applicable limit A: 18 mm
b. Fluid stain from oil or oil leakage
3. Deterioration of wheel cylinder
Clearance between < .006 in.
cylinder and piston (0.15 mm)
9.2.7 BRAKE BOOSTER
Oil leakage
9.2.8 BRAKE SHOE LINING
1. Brake shoe
Check proper functioning, rust or wear
2. Peeling off, scratches or wear of brake lining
Thickness of lining > .039 in. (1 mm)
3. Corrosion of anchor pin
4. Deterioration of return spring
Free length < 4.13 in. (105 mm)
Thickness of hook > .078 in. (2.0 mm)
9.2.9 BRAKE DRUM
Cracks scratches or wear of brake drum:
Measure the following dimensions, and check whether they are allowable values.
Inside diameter of drum (all models) < 12.28 in. (312 mm)
9.2.10 BACK PLATE
1. Deformation, cracks or scratches
2. Tightening torque for mounting bolt
LOCTITE #271 (thread hole)
torque
130 - 144 ft/lbs. (176 - 196 Nm)
{18.0 - 20.0 kgm}
9-7
9. WHEEL BRAKE
9.3 TESTING AND ADJUSTING
9.3.1 INSPECT BRAKE ASSEMBLY
1. Adjust shoe clearance.
2. Test wheel brake adjustment.
a. Pull cable (1) by finger in the direction shown by the
arrow in the diagram on right causing the lever to
engage with the next tooth.
b. Release the cable and the lever returns to the original
position after clicking one notch.
NOTE: When the lever fails to function properly, check
the lever for position above the adjuster screw.
The lever is designed to contact the adjuster wheel with
clearance (a) between 0.20 - 0.28 in. (5 - 7 mm) from the
center of the adjuster screw.
NOTE: When the lever position is incorrect, the lever cannot
mesh with the wheel and the wheel may fail to func-
tion even if the lever operates.
3. Remedy for Malfunction
a. Check to make sure that the cable guide fits properly
to the specified hole on the secondary shoe.
b. Check to make sure that the adjuster spring can
properly fit to the specified hole on the primary shoe.
c. Replace the cable with a new one, if necessary.
d. Replace the lever with a new one, if necessary.
e. Replace the adjuster assembly, if necessary.
9.3.2 ADJUST BRAKE SHOE CLEARANCE
1. Chock the rear wheels.
2. Raise the front, drive wheels, up off the ground.
3. Position blocks under the frame to support the truck.
4. Release the parking brake.
5. Remove the rubber cap to access the adjustment gear.
6. Turn gear (1) in direction (A) or toward the brake shoes repeatedly with a screwdriver until the brake shoes
touch the brake drum. Turning of each notch makes a clicking sound.
7. Turn the wheels by hands to feel braking effect.
8. Obtain two screwdrivers.
9. Gently push the lever (2) so that it will miss each gear
notch using one screwdriver.
NOTE: Be careful not to push too hard.
10. Turn the gear (1) toward direction (B) counting by twenty-
one (21) notches with the second screwdriver while the
first one is still holding the lever.
9-8
9. WHEEL BRAKE
IMPORTANT
Since no clicks are made here, count the number of notches watching through the hole of the rubber cap (3) for
carrying out the adjustment.
11. Install the rubber cap (3).
12. Turn the wheels by hand and check to make sure that there is no brake dragging.
IMPORTANT
The clearance between the brake shoe and brake drum should be adjusted approximately to 0.02 in. (0.55 mm)
(clearance of diameter) with this adjustment.
9.3.3 BLEED AIR FROM BRAKE PIPING
IMPORTANT
• Before starting to bleed air, adjust the brake shoe clearance to the specified .016 - .022 in. (0.40 - 0.56 mm).
• From time to time, refill the brake fluid to prevent the brake fluid in the reserve tank from emptying while carry-
ing out air bleeding. If air is drawn into the system from an empty reservoir during bleeding, start the procedure
over again keeping the brake fluid filled.
1. Remove the cap from the air bleed plug (1) of the brake
wheel cylinder.
2. Install one end of a plastic hose (2) for air bleeding to the
plug and put the other end of the hose into a container of
brake fluid.
NOTE: The plastic hose should be transparent.
3. If inspector is alone, connect a string or a wire (3) to the
upper arm of brake pedal (4).
2
2
9-9
9. WHEEL BRAKE
4. Let the other end of string or wire (3) loose free in
approximately 12 inches through the space between the
frame (4) and the dashboard (5).
5. Slowly pull out the string or the wire (3) connected with
the brake pedal (4) arm from the front of the forklift so as
to compress the air inside the brake piping and hold it.
NOTE: If more than one person is present, one inspector
should press the brake pedal.
6. Loosen the air bleed plug (1) of the brake wheel cylinder
approximately 3/4 turn to the left and depress the brake
pedal to bleed the air in the piping along with the brake
fluid. Then, while holding the pedal down, tighten the
bleed plug (1) while bleeding the brake fluid.
NOTE: In this stage, keep pulling the string or the wire for a while.
7. After tightening the bleed plug, release the brake pedal.
8. Repeat the step 3, 4, and 5 of the above until no more
bubbles come out of the hose.
9. Carry out the other side adjustment with the same steps.
10. Repeat air bleeding of the brake and check again to
make sure that no more air left in the brake piping.
11. Depress the brake pedal to check it for normal response.
12. Depress the brake pedal with force of 196 N or 20 kgf to b
measure the pedal stroke (a). Check to make sure that
the pedal stroke (a) is within 2.17 - 2.95 in. (55 - 75 mm)
when depressing the pedal. a
2.17 - 2.95 in.
Pedal stroke (a) when depressed
(55 - 75 mm)
0 - 0.16 in.
Play (b)
(0 - 4 mm)
13. Remove the hose (2) from the air bleed plug (1).
14. Tighten the air bleed plug and install the cap.
torque
Air bleed plug: 4.3 - 6.5 ft/lbs. (5.9 - 8.8 Nm) {0.6 - 0.9 kgm}
15. Refill the brake fluid up to the MAX line (C) on the reserve
tank (5) of upper master cylinder, which shows the
specified fluid level.
16. Remove the string or the wire (3) connected to the brake
pedal arm.
9-10
9. WHEEL BRAKE
9.4 REMOVAL AND INSTALLATION
9.4.1 REMOVAL
1. Chock or block the rear wheels.
2. Place wooden blocks under the bottom of the truck frame
to lift the front wheels.
3. Apply the parking brake.
4. Remove the hub nut and the torque shaft (3).
5. Release the parking brake.
6. Remove the bolts (4).
7. Remove the lock nut (5) with a special tool (80 mm
double face box). 4
8. Remove the hub (do not twist upside down).
9-11
9. WHEEL BRAKE
9.4.2 INSTALLATION
1. Install back plate (when removed)
a. Apply Loctite to the mounting bolts (1).
LOCTITE #271
b. Tighten as follows:
torque
130 - 145 ft/lbs (176 - 196 Nm) {18 - 20 kgm}
1
2. Install hub
6
a. Install a new oil seal. 9
NOTE: Apply G2-L1 grease to the lip surface of the oil
seal.
b. Fill G2-L1 grease in the bearing (7) and install it to the
hub (8).
c. Remove any dirt and oil from the inside face of the
7
brake drum (9) completely.
d. Install the hub to the shaft tube. 8
e. Tighten locknut (5) so that the starting torque of the
hub will conform to the following:
4
torque
Starting Torque: 4.5 - 11.6 ft/lbs (6.1 - 15.7 Nm) {62.5 -
160 kgm}
f. Apply Loctite to bolt (4) and tighten.
Loctite #271
3. Install front axle and torque shaft.
a. Install the torque shaft (3).
b. Tighten the bolts (2) and tighten as specified below:
torque
72.3 - 93.7 ft/lbs 98 - 127 Nm {10 - 13 kgm} 2
c. Install the front axle.
1
d. Tighten the hub nuts (1) and tighten as specified
below:
torque
217 - 361 ft/lbs 294 - 490 Nm {30 - 50 kgm} 3
9-12
9. WHEEL BRAKE
9.5 DISASSEMBLY AND ASSEMBLY
9.5.1 WHEEL BRAKE
WHEEL BRAKE ASSEMBLY
13 - 19.5 ft/lbs.
torque 17.6 - 26.4 Nm
{1.8 - 2.7 kgm}
5 (*1)
*1
A
1 2
torque
*1. Tightening Torque for Back Plate Mounting Bolt: 130 - 144 ft/lbs. (176 - 196 Nm) (18 - 20 kgfm)
Lubrication for Back Plate Mounting Bolt: LOCTITE #291
Item Unit Wheel Brake
Type – Front wheel internal expanding hydraulic type
Structure – Duo servo
Brake Drum Inner Diameter in. (mm) 12.2 (310.0)
Lining Material – Resin molded (Adhesive type)
Width in. (mm) 2.36 (60.0)
Thickness in. (mm) .224 (5.7)
Wheel Cylinder Inner Diameter in. (mm) 1.25 (28.58)
9-13
9. WHEEL BRAKE
9.5.2 BRAKE MASTER CYLINDER
MASTER CYLINDER ASSEMBLY
11
9 10
8
2 1
4 12
13
5
17
6 14
7
15
16
1. Cylinder 8. Bleeder Valve
2. Piston Assembly 9. Bleeder Cap
3. Snap Ring 10. Valve Spring
4. Boot 11. Seat
5. Push Rod 12. Valve Rubber
6. Nut 13. Gasket
7. Yoke 14. Bolt
9-14
9. WHEEL BRAKE
DISASSEMBLY
1. Remove the yoke and boot.
2. Remove stopper pin (1) with a flat-headed screwdriver.
NOTE: When it is hard to remove the stopper pin, push on
the push rod (2) lightly.
3. Remove the stopper wire (3) from the cylinder (4) with a
flat-headed screwdriver.
4. Remove the piston assembly, the spring, the check valve
and valve seat.
• Be careful not to damage the cylinder, the piston or
the cup.
• When carrying out disassembly, make sure that you
understand the structure of the cylinder well in
advance. Then, it is recommended that all the disas-
sembled parts be put in order according to the disas-
sembly procedures.
• Never disassemble the piston assembly.
• Be careful not to squeeze the outer surface of the cyl-
inder with a vise.
1 - Base 2 - Lip 3 - Base 4 - Lip
9-15
9. WHEEL BRAKE
INSPECTION AND ADJUSTMENT
Part Name Check Item Remedy
Remove small scratches with sandpaper.
Scratches, uneven wear or corro-
Cylinder If there are critical scratches that adversely affect the cup,
sion of inner surface
replace with a new cylinder assembly.
Remove small scratches with oilstone.
Scratches, uneven wear or corro- If there are critical scratches that adversely affect the inner
sion face of cylinder or the cup, replace with a new piston
Piston assembly.
If the clearance is greater than the repair limit, replace it
Clearance between cylinder and
with a new one.
piston
Repair Limit: 0.15 mm
Even if the scratches are very small, replace if with a new
Scratches on lip
piston assembly.
If there is harmful pitting, replace with a new piston
Pitting of base
assembly.
If there is abnormal deterioration, wear or swelling,
Wear or swelling
Cup replace with a new piston assembly.
If below the repair limit, replace with a new piston assem-
bly.
Repair Limit: 0.4 mm
Clearance
Note: The cup belongs to the group of parts to be replaced
periodically. In general, it is recommended that such parts
be replaced whenever disassembled.
Deformation, scratches or wear
If there is abnormal deformation, scratches or wear,
Piston Assembly of valve rod, valve cup, spring
replace with a new piston assembly.
and thimble
Springs showing critical scratches must be replaced with
Scratches, wear or fall
new ones.
Spring Those below the repair limit must be replaced with a new
Free length one.
Repair Limit: 2.76 in. (70 mm)
Push Rod Bend or deformation Those bent or deformed must be replaced with a new one.
Those with cracks, damage or scratches must be replaced
Cracks damage or scratches
with a new one.
Boot
Tightening allowance between Those with no tightening allowance, or an extremely little
cylinder and rod tightening allowance, must be replaced with a new one.
Even if the cracks are extremely small, replace with a new
Cracks
part.
Filler Union Those with critical discoloration must be replaced with a
Discoloration
new one.
Scratches Those with scratches must be replaced with a new one.
Bushings displaying cracks or critical deterioration must
Bushing Cracks or deterioration
be replaced with a new one.
9-16
9. WHEEL BRAKE
ASSEMBLY
1. Wash all parts to be reused in alcohol or brake fluid.
• Cleanliness is essential when working with brake parts.
• Do not soak rubber parts, such as cups, boot, etc., in alcohol for more than 30 seconds.
• Do not use any fluid other than alcohol or brake fluid when cleaning parts.
• Never use mineral oil, petroleum or gasoline. Mineral oil will cause the rubber parts to swell up and
become unusable.
• After washing the parts, keep them in a clean place to prevent contamination by dirt or dust.
• Ensure no dirt or dust gets on or into the parts during assembly.
• Do not damage the cylinder, piston or cup.
2. Coat inside surface of cylinder and outside circumference of piston evenly with rubber grease or brake fluid.
3. Assemble the valve seat and the check valve to the cylinder housing.
4. Assemble the spring to the piston assembly.
11
9 10
8
2 1
4 12
13
5
17
6 14
7
15
16
5. Insert the piston assembly into the cylinder.
NOTE: When doing this, align the direction of the piston groove with the direction of the stop pin hole in the cylin-
der.
6. Fit the gasket and o-ring to the stop pin.
7. Push in piston and install to the cylinder.
torque
Torque the stop pin to 22.1 - 30.1 lbs./in (2.5 - 3.4 Nm).
8. Insert stop plate, push in piston lightly with a finger, and secure to cylinder with stop wire.
9. Insert push rod.
10. Attach the boot, nut and yoke in order to the push rod.
torque
Torque nut to 69.0 - 104.4 lbs./in (7.8 - 11.8 Nm).
9-17
9. WHEEL BRAKE
9.6 MAINTENANCE STANDARD - MASTER CYLINDER
11
9 10
8
2 1
4 12
13
5
17
6 14
7
15
16
1. Cylinder 8. Bleeder Valve
2. Piston Assembly 9. Bleeder Cap
3. Snap Ring 10. Valve Spring
4. Boot 11. Seat
5. Push Rod 12. Valve Rubber
6. Nut 13. Gasket
7. Yoke 14. Bolt
Repair
Standard Size
Check Item Limit Remedy Ref. No.
in. (mm)
in. (mm)
Clearance between Cylinder .0008 - .0040 Replacement
.006 (0.15) 1.2
and Piston (0.020 - 0.105) (Cylinder Assembly)
Primary: approx. .04 (1.0) Replacement
Tightening Clearance of Cup .016 (0.4) 2
Secondary: approx. .047 (1.2) (Cylinder Assembly)
Free Length for Spring 3.1 (78.8) 2.76 (70) Replacement 2
NOTE: The numbers shown in the Ref. No. on the right refer to those in the diagram of the component parts.
9-18
