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Takeuchi compact excavator TB125, TB135, TB145 / diesel TNE / diesel Yanmar. Service Manual - page 31

IV-168-26

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

Anti-Cavitation Valve

1. Install the spool (4), the spring seat (3) and the

spring (2) in the valve vody.

2. Fit the O-ring on the plug (1), then install the

valve body.

Plug: 53.9

4.9 N·m

3. Install the O-ring in the anti-cavitation valve,

then install the anti-cavitatio on the valve body.

Cap Screw: 36.9

1.9 N·m

IV-168-27

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

Parts

INSPECTION AND ADJUSTMENT

Checking the Parts

There should be no abnormal scratches,
wear or seizing.

Floating Seal

Sliding Surface

Replace

Area Checked

Judgement Criteria

Treatment

There should be no abnormal scratches,
wear, flaking, etc. in the ball or race.

Sliding Surface

Surface of Gear Teeth

There should be no abnormal scratches,

wear or flaking of the tooth surfaces (if
there has been pitting which covers 5%
or more of the engagement portion of
the tooth surface).
There should be no abnormal scratches,
wear or flaking of the rotating surface.

Front of cage and roller ro-
tating surface.

There should be no abnormal scratches,
wear or flaking of the rotating surface.

Surface condition of inner
race rotating surface.

There should be no abnormal scratches,
wear or flaking.

Surface of needle.

There should be no abnormal scratches,
wear or seizing.

Front of sliding surface

There should be no abnormal scratches,
wear or flaking in the tooth surfaces (if
there has been pitting which covers 5%
or more of the engagement portion of
the tooth surface).

Front of Gear Tooth Sur-
faces

There should be no abnormal scratches
(0.02 mm or greater), wear or seizing,
etc.

Front of sliding surface.



There should be no scratches or abnor-
mal wear.

Surface of oil seal.

There should be no abnormal scratches,
wear or flaking in the ball and race.

Front of sliding surface.



There should be no abnormal scratches
(0.02 mm or greater), wear or seizing.

0.04 mm or greater

Front of the surface which
slides with the sliding sur-
face of the piston assembly.
Clearance with the piston
assembly.

There should be no abnormal scratches
(0.02 mm or greater), wear or seizing.

Front of the surface which
slides with the valve plate.

0.04 mm or greater

Clearance with cylinder
block
Front of the surface which
slides with the swash plate.

There should be no abnormal scratches
(0.02 mm or greater), wear or seizing.
0.4 mm or greater

Clearance between piston
and shoe.

Angular Bearing

Planetary Gears

Inner Race

Needle

Thrust Washer

Housing, Sun Gear,
Drive Gear

Thrust Plate

O-ring
Shaft

Ball Bearing

Oil Seal
Swash Plate

Cylinder Block

Piston Assembly

Replace

Replace
Replace

Replace

Replace
Repair by lapping
(#1000) or replace.

Repair with wrap
(#1000) or replace
the cylinder block
and piston assem-
bly at the same
time.

Replace

IV-168-28

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

Parts

Area Checked

Judgement Criteria

Treatment

Repair by lapping
(#1000) or replace.

Valve Plate

Front of the surface which
slides with the spool.

There should be no abnormal scratches
(0.02 mm or greater), wear or seizing.

Front of the surface which
slides with the spool.

There should be no abnormal scratches,
wear or seizing.
There should be no abnormal scratches,
wear or seizing.

Front of the surface which
slides with the base plate.

There should be no abnormal scratches,
wear or seizing.

Front of the surface which
slides with the check valve.

There should be no abnormal scratches,
wear or seizing.

Front of the surface which
slides with the spool.

There should be contact with the seat
around the entire circumference.

Surface of spool and seat.

Base Plate

Spool

Check Valve

Replace the base
plate and the spool
at the same time.

Replace the spool
and the check
valve at the same
time.

IV-168-29

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

• Repair or replace the damaged piping.
• Remove the foreign matter and repair

or replace the damaged parts.

• Clean it.

TROUBLESHOOTING

Hydraulic Motor

Symptom

Does not move.

• Equipment other than the motor, coun-

terbalance valve or speed reducer is
malfunctioning.

• Check if the proper pressure is reached

on the motor inlet port side, then check
each device and repair if necessary.

Probable Causes

Remedy

• Replace the abnormally worn parts.

• Replace the damaged parts.

• Hydraulic oil is escaping due to ab-

normal wear of motor sliding parts.

• Principal motor parts are malfunc-

tioning due to damage.

• The proper volume of hydraulic oil is

not being supplied to the motor due to
the hydraulic pump, control valve,
etc.

• Check if the proper pressure is reached

on the motor inlet port side, then check
each device and repair if necessary.

• The motor’s volumetric efficiency is

dropping.

• Check if the sliding parts are abnor-

mally worn, then repair or replace the
worn parts.

• High pressure hydraulic oil is leaking

and flowing out of the drain port due
to wear of the motor's sliding parts.

• Bearings are worn.

• Replace the abnormally worn parts.

• Replace the bearings if they are abnor-

mally worn.

• Oil is leaking due damage to oil seals

or O-rings.

• Replace the oil seals and O-rings.

Motor won’t speed up.

Changes in rotational speed
are great.

Oil is leaking.

Counterbalance Valve

Symptom

Probable Causes

Remedy

Does not move or rotation is
slow.

Spool does not switch.
• No hydraulic oil is arriving.
• Foreign matter is caught.

• The orifice is clogged up.
The spool won’t return.
• Foreign matter gets caught.

• A spring is missing.
• A spring is damaged.
• The orifice is clogged up.

• Remove the foreign matter and repair

or replace the damaged parts.

• Install the spring.
• Replace the spring.
• Clean it.

Spool return is fast.
• The spring seat is missing.

• Install the spring seat.

The spool does not return.
• Foreign matter gets caught.

• A spring is damaged.
• The orifice is clogged up.

• Remove the foreign matter and repair

or replace the damaged parts.

• Replace the spring.
• Clean it.

Won’t stop or stopping is
slow.

Shock is great when stopping.

Valve makes an abnormal
noise.

IV-168-30

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

Symptom

Probable Causes

Remedy

• Remove the foreign matter and repair

or replace the damaged parts.

• Install the spring.
• Replace the spring.

2-speed Control Function

Machine veers during travel. Spool doesn’t switch over.

• Foreign matter is caught.

• A spring is missing.
• A spring is damaged.

Anti-Cavitation Valve

Symptom

Probable Causes

Remedy

Does not move or rotation is
slow.

Spool seat is faulty.
• Foreign matter gets caught.

• A spring is damaged.

• Remove the foreign matter and repair

or replace the damaged parts.

• Replace the spring.

Spool seat is faulty.
• Foreign matter gets caught.

• Remove the foreign matter and repair

or replace the damaged parts.

Valve makes an abnormal
noise.

Test Run

Upon completion of servicing and inspection, install
the travel motor and perform the test run on the
machine (no crawler should be installed).
1. Fill the piston motor case with hydraulic oil.

Bleed air completely from each part of the piping.
• Fill up the motor case until the oil comes out of

the drain port (1) on the upper side.

• When reassembling, make sure that the reduc-

tion gear case is filled with lubricating oil up to
the specified level.

2. Run the travel motor at low RPMs.

• Engine at low RPMs.
• If there is any air left in the circuit, an unusual

noise may be heard from the valve. Run the
motor until no air is left.

• Check for any oil leakage.

3. Run the travel motor at high RPMs.

• Engine at the rated RPMs.
• Make sure that the machine is running without

any noise or vibration.

IV-169

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

1. Retainer
2. Ball
3. Shaft
4. Cylinder Block
5. Valve Plate
6. Piston
7. Shoe
8. Shoe Holder
9. Guide
10. Swash Plate

TRAVEL MOTOR (TB135)

CONSTRUCTION

Hydraulic Motor

11. Pin
12. Spring
13. Retainer
14. Bearing
15. Bearing
16. Spacer
17. Brake Piston
18. Spring
19. Snap Ring
20. Backup Ring

21. O-ring
22. O-ring
23. Backup Ring
24. Friction Disc
25. Center Disc
26. Oil Seal
27. Pin
28. Pin
29. 2-Speed Piston

G4D500

IV-170

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

1. Housing
2. Cover
3. Carrier 2
4. Gear B1
5. Gear B2
6. Gear S1
7. Snap Ring
8. Flange Holder

Reduction Gears

9. Thrust Washer
10. Thrust Collar
11. Snap Ring
12. Collar
13. Needle
14. Needle
15. Floating Seal
16. O-ring

17. Bearing
18. Thrust Washer
19. Ring
20. Pin
21. Plug
22. O-ring
23. Plug
24. Snap Ring

25. O-ring
26. Pin
27. Thrust Washer
28. Snap Ring
29. Pin
30. Snap Ring
31. Snap Ring

G4D501

IV-171

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

Counterbalance Valve, 2-speed Control Valve, Relief Block Assembly

1. Valve Body
2. Spool
3. Check Valve
4. Spring
5. Plug
6. O-ring
7. Spring Guide
8. Spring
9. Cap
10. O-ring
11. Orifice

12. Spool
13. Spring
14. Plug
15. O-ring
16. Plug
17. Plug
18. Orifice
19. Valve Body
20. Relief Valve Assembly
21. Relief Housing
22. Poppet

23. Seat
24. Spring Seat
25. Spring
26. Plug
27. O-ring
28. O-ring
29. Backup Ring
30. Piston
31. O-ring
32. Stopper
33. Spacer

34. O-ring
35. O-ring
36. O-ring
37. O-ring
38. O-ring
39. O-ring
40. Shuttle
41. Spacer

IV-172

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

C4D554

C4D555

OPERATION

Hydraulic Motor

9 pistons (2) are fitted in the cylinder block (1) and
there is a valve plate (3) with two half moon ports, B
and C in the end. Also, the cylinder block (1) rotates
freely and is joined to the shaft (4) via the spline. On
the other band, the swash plate (5) is fastened to the
housing.
When high pressure oil is introduced into port B, one
piston (2) makes contact and force F bears on the
swash plate (5).
F = P

A P: Pressure A: Piston Sectional Area

The force F which the piston (2) applies to the swash
plate (5) is divided into force F1, which pushes the
plate, and force F2, which rotates the cylinder block
(1). The total sum of the components in the direction
of rotation of the high pressure side piston generates
a rotational force in the cylinder block (1) and via the
spline, torque is transmitted to the shaft (4), turning it.
Conversely, if high pressure oil is introduced to port
C, rotation is the reverse of the above.

Counterbalance Valve

If high pressure oil is introduced to port P1, the oil
pushes the check valve (6) up. This causes oil to flow
through the motor port M1 and to flow into chamber
B of the pilot portion and fill it. When hydraulic oil
flows the motor from port M1 and acts to turn the
motor, even if oil returns from the motor and flows
into port M2, since the flow is cut off by the check
valve (6), the pressure at port P1 and in chamber B
rises. If the pressure in chamber B becomes higher
than the set valve of the spring (7), the spool (8) moves
to the left side and ports M2 and P2 open up, causing
the motor to turn.

If the motor’s turning becomes too fast, and the
amount of oil flowing out of port M2 is greater than
the amount of oil flowing into port M1, the pressure
in port P1 and chamber B drops. When the pressure in
chamber B drops below the set valve of the spring (7),
the spool (8) attempts to return to the right side. As a
result, since the resuming oil is constricted at portion
D, back pressure is generated at port M2 and the
motor’s turning is slowed.

IV-173

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

C4D556

When the motor is slowed, the pressure in port P1 and
chamber B rises again and the spool (8) moves to the
left aide, eliminating the back pressure generated at
port M2. In this way, the motor is controlled so that it
rotates at a speed appropriate for the amount of oil
flowing into it.

If the high pressure hydraulic oil introduced into port
P1 is cut off, the pressure at ports P1 and P2 becomes
the same and the spool (8) returns to the neutral
position by spring force. For this reason, the oil in
chamber B is pushed out at port P1. At this time, the
flow of oil is restricted by the orifice (9) as it is
returning to port P1, so the spool (8) returns to the
neutral position slowly. In this way, the motor is
stopped while the shock during stopping is absorbed.

Relief Valve

Operation 1

When the Motor is Started
When the motor is started, since the inertial load is
great, the pressure of the oil required to accelerate it
rises. If this pressure reaches the relief valve set
pressure, the relief valve operates and oil returns to
port M2.
In this way, the motor begins to turn as it relieves the
relief valve, and as the rotational speed increases, the
amount of relief decreases until it stops.
In this way, the shock during starting is absorbed.

When the Motor is Stopped
When the motor is stopped, the return circuit is closed
off.
However, since the motor tends to want to continue
rotating due to inertial energy, the pressure in port M2
rises. When this pressure reaches the relief valve’s set
pressure, the relief valve operates and oil flows to port
M1. In this way, the flow of oil to port M1 prevents
cavitation from occurring as it absorbs the shock
during stopping.

G4D503

G4D504

IV-174

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

G4D507

G4D508

Operation 2

Since this relief valve has a shockless mechanism, it
operates in 2 steps.
1st Step
When relief valve operation starts, the pressure in
chamber B (P1) is kept at a pressure which is lower
than that in chamber C while the pressure in chamber
A (P) becomes higher than the pressure of the oil
flowing in.
At this time, there are two forces acting on the poppet
(10), force (F), which attempts to move the poppet
(10) to the left and force (F1) which pushes against the
seat on the right side. Since F = P 5 A, F1 = P1 5 A1,
P > P1 and A > A1, the poppet (10) is moved to the left
by this force “F – F1”.
This opens a supply side circuit from chamber A and
lets the pressure escape. That is, during the time piston
(11) is moving to its stroke end, the relief valve
operates at low pressure (about 1/3 the set pressure).

2nd Step
When the piston (11) reaches the stroke end, the
pressure in chamber B rises and the pressures in
chamber A and chamber B equalize. At this time, the
force moving the poppet (10) to the left side becomes
“P = P1”, so this becomes “A – A1” and the relief
valve operates at the specified set pressure.

2-Speed Mechanism

2-speed control valve
When high-pressure oil led to the port M1 and the
travel 2-speed solenoid valve (1) is set to speed 1, the
chamber C is connected to the tank via the travel 2-
speed solenoid (1), so that a low pressure is obtained.
For this reason, the spool (2) is pushed to the left by
the spring (4), the swash plate control piston chamber
(3) and the tank port (T) are connected, and there is no
force pushing the swash plate (5) in upward direction.

When the travel 2-speed solenoid valve (1) is switched
to speed 2, the pressure oil from the travel 2-speed
solenoid valve (1) flows to the chamber C, the spool
(2) is moved to the right, and the port M1 is connected
with the port A, while the port M2 is connected with
the port B. Then the pressure oil from the port P1
moves the shuttle spool (12) to the right and flows to
the swash plate control piston chamber (3). This
causes operation of the control piston (11), and the
swash plate (5) is pushed up.
At the time of engine stop, no pressure oil is supplied
any longer, and the spring (4) returns the spool (2) to
the speed 1 position.

IV-175

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

C4D557

C4D558

5 4

E5D512

Swash Plate

The swash plate (5) has 3 planes, A, B and C, as shown
in the figure, and it is assembled in such a way that its
angle of inclination in the flange holder (6) can varied
by two balls (7). When the 2-speed control valve is
switched to the 1st speed side, the swash plate control
piston chamber is connected to tank port and the
swash plate (5) is stabilized at plane A, forming swash
plate angle

, by the piston assembly (8) and the force

of the springs (9), (10), achieving 1st speed (low
speed) motor rotation.
When the 2-speed control valve is switched to 2nd
speed, the swash plate control piston chamber (3) is

connected to the motor drive pressure port and the
swash plate (5) stabilizes at plane B due to the equi-
librium between the force of the springs (9), (10) and
the force of the control piston (11), thus, assuming
swash plate angle ß. In this way, 2nd speed (high
speed) motor rotation is achieved.
When the engine is stopped, the pilot pressure of the
2-speed control valve is cut off, so the swash plate (5)
is stabilized at the swash plate a plane A by the force
of the springs (9), (10), changing to the 1st speed side.
For this reason, when starting, the motor also is in 1st
speed.

Parking Brake

The center discs (1) are connected to the flange holder
and the friction discs (2) are connected to the cylinder
block (3) via the spline, respectively. The center discs
(1) and friction discs (2) are pressed against the flange
holder (6) by the springs (4) via the brake piston (5).
The friction force between these discs generates the
brake torque to prevent the cylinder block (3) from
rotating.

When the pressure oil is introduced into the motor, the
spool of the counterbalance valve moves and the oil
flows from the parking brake release port (7) into the
brake piston chamber (8). The oil pressure overpow-
ers the spring force and moves the brake piston (5) to
the right. This generates a clearance between the
center discs (1) and friction discs (2) to release the
parking brake. When the motor stops, the spool re-
turns to the neutral position to close the parking brake
release port (7). The pressure oil in the brake piston
chamber (8) is introduced into the motor case and the
spring (4) operates the parking brake.

Reduction Gears

“IV-145”

IV-176

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

DISASSEMBLY AND ASSEMBLY

General Cautions

• Carry out disassembly and assembly operations in

a clean place and provide clean containers to place
the disassembled parts in.

• Before disassembly, clean around the ports and

remove the paint from each joint using a wire
brush.

• Wash the disassembled parts and dry them with

compressed air. Do not use a rag, as this could
cause clogging of dirt.

• Make match marks on each part so that they will be

assembled in the same positions when reassembled.

• Replace all seals with new ones each time the unit

is disassembled, coating them lightly with grease.

• Check each part to make sure there is no abnormal

wear or seizing and use sandpaper, etc. to remove
any burrs, sharp edges, etc.

The following describes the assembly procedure. For
disassembly, follow the procedure in the reverse
order referring to the construction diagram.

Assembly

Counterbalance Valve and Hydraulic Motor

1. Fix the body with a vise and mount the spool on

the valve body.
• To prevent the outer surface of the valve body

from being damaged, insert a protector such as
an aluminum plate between the valve body and
the vise.

• Do not disassemble the spool assembly into

parts.

2. Mount the rings (1) and springs (2) on both sides

of the spool.

3. Fit the O-ring to the plug, and tighten the plug on

both sides of the valve body.
• Plug tightening torque:

196~245 N·m (20~25 kgf·m)

C4D561

C4D562

C4D563

IV-177

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

4. Mount the second speed spool (4) and spring (5)

on the valve body.

5. Fit the O-ring to the plug and tighten the plug to

the valve body.
• Plug tightening torque:

46~51 N·m (4.7~5.3 kgf·m)

6. Install the shuttle.

7. Fit the O-ring to the plug and tighten the plug to

the valve body.
• Plug tightening torque:

12~23 N·m (1.2~2.3 kgf·m)

C4D564

C4D565

IV-178

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

8. Mount the large and small O-rings on the valve

body.

9. Press fit the oil seal into the flange holder.

• As the oil seal is be inserted, do not disas-

semble it unless necessary.

• Fill between the lips of the oil seal with grease.

10. Install the pin.

11. Install the 2-speed piston.

G4D514

G4D516

IV-179

HYDRAULIC UNITS

TRAVEL MOTOR

TB125, 135, 145

12. Mount the shaft on the flange holder.

• The bearing has been inserted and cannot be

disassembled.

• Be careful not to damage the oil seal by the

shaft.

13. Install the balls and swash plate.

• Apply hydraulic oil to the sliding surfaces of

the swash plate.

14. Mount the retainer (6), spring (8) and retainer (7)

on the cylinder block and fix them with the snap
ring (9).

15. Fit the three pins (10) to the cylinder block.

C4D568

C4D569

C4D571

C4D567

C4D5701

Content .. 29 30 31 32 ..