Takeuchi compact excavator TB125, TB135, TB145 / diesel TNE / diesel Yanmar. Service Manual - page 12

III-112

MACHINE CONFIGURATION

ELECTRICAL SYSTEM

TB125, 135, 145

Operation of the cluster gauge

1. When the key switch is turned on, the initial check

circuit in the controller is actuated to turn on all
the lamps of the cluster gauge and to sound the
buzzer for about one second.
• Confirm that all the lamps go on.

2. When about one second has elapsed after turning

on the key switch, the lamps (except the charge
lamp and the engine oil pressure lamp) go off and
the buzzer stops. In this state, the cluster gauge is
ready and waits for input. The coolant tempera-
ture gauge is also actuated.

3. When the engine is started, the charge lamp and

the engine oil pressure warning lamp go off. The
hour meter is also actuated and its indicator flashes.

III-113

MACHINE CONFIGURATION

ELECTRICAL SYSTEM

TB125, 135, 145

Miscellaneous circuits relating to the ACC
fuse

1. Lever lock circuit (for both cab and canopy types)

The voltage (+12 V) from the ACC fuse is applied
to the lever lock solenoid, through the limit
switches R and L for the canopy type or through
the limit switch L only for the cab type. During
normal operation, the lever lock solenoid is turned
on and the current flows. When the lever is
locked, the lever lock solenoid is turned off.
When the lever is locked, the lever lock solenoid
turns off. If the lever lock limit switch should
malfunction, the attachment is locked.
If this happens and the attachment must be moved
for repairs, this can be done using emergency
lever lock release connectors A and B.
The lever lock release connectors A and B for
emergency use are taped on the main harness
under the engine muffler. Connecting them will
release the lever lock.

2. Water heater circuit (standard for the cab type,

optional setting for the canopy type)
The voltage (+12 V) from the ACC fuse is applied
to the water heater unit through the diode that
prevents the counterelectromotive force, and the
minus terminal is grounded through the heater
switch of the control panel L. The heater switch
can be set to two stages for controlling the air
volume of the heater: the first stage provides a
small volume and the second stage provides a
large volume.

3. Light circuit (for both cab and canopy types)

The voltage (+12 V) from the ACC fuse is applied
to the boom light, taillight and the illumination
lamp of the cluster gauge through the light switch.

4. Windshield wiper circuit (for cab type)

The voltage (+12 V) from the ACC fuse is applied
to the windshield wiper motor and windshield
washer motor through the windshield wiper and
washer switch of the control panel L.

WARNING

To prevent serious accidents, never use the
emergency lever lock release connectors during
normal operations.

III-114

MACHINE CONFIGURATION

ELECTRICAL SYSTEM

TB125, 135, 145

5. Cigarette lighter socket circuit (for cab type)

This circuit can be used to light a cigarette or as an
optional power outlet. The maximum output is
120 watts.

6. Maintenance light socket circuit (for all models

of European specifications)
This circuit is a power socket for connecting a
maintenance light. The maximum output is 60
watts.

7. Radio circuit (for cab type)

The voltage (+12 V) from the ACC fuse is di-
rectly applied to the radio.

8. Travel alarm circuit (For all models: optional

feature to be selected before shipment from the
factory)
The voltage (+12 V) from the ACC fuse is applied
to the travel alarm relay through the travel alarm
proximity switches (R) and (L) to activate the
travel alarm buzzer.

9. Lift alarm sensor circuit (optional)

When lifting loads using a boom, a load exceed-
ing the stipulated weight may cause the lift to lose
its balance and overturn. However, if the lift
alarm sensor circuit is switched on, a horn will
automatically sound when you attempt to lift a
load that is too heavy, warning of the danger of the
lift overturning.
In usual excavating operations, this circuit should
be switched off.

10. Auxiliary circuit

If you press the push button switches A and B on
the left control lever, you will be able to turn the
circuit breaker and other auxiliary circuits on and
off at your fingertips. The voltage (+12 V) from
the ACC fuse is applied to the auxiliary relay
through the push button switches on the left
control lever to activate the solenoid valve of the
auxiliary circuit.

11. Air conditioning circuit (for model TB145: op-

tional feature to be selected before shipment from
the factory)
The voltage (+12 V) from the ACC fuse of 30 A
is applied to the power terminal of the air condi-
tioning unit.

Miscellaneous circuits relating to the B+ fuse

The circuits that cannot be turned off by the key
switches are as follows:

1. Horn circuit

The voltage (+12 V) from the B+ fuse is applied
to the horn relay through the horn switch set on
the control lever (R) to activate the horn.

2. Room light circuit (for cab type)

The voltage (+12 V) from the B+ fuse is applied
to the room light mounted on the cab.

3. Radio circuit (for cab type)

The voltage (+12 V) from the B+ fuse is applied
to the station select memory circuit of the radio
mounted on the cab. It also drives the clock
mounted on the radio.

III-115

MACHINE CONFIGURATION

PROPORTIONAL CONTROL

TB125, 135, 145

PROPORTIONAL CONTROL

The driving current flowing through the proportional control solenoid valve (4) is controlled by the proportional
control lever (2) of the left pilot valve (1) and the proportional controller (3), and the flow rate of the auxiliary piping
is changed by the proportional control solenoid valve (4) controlling the pilot pressure of the control valve
[auxiliary] (5).

By using the built-in current limiting circuit (PWM
control), the proportional controller (3) controls the
driving current of solenoids A and B of the propor-
tional control solenoid valve (4) in response to the
proportional signals input by the tilted proportional
control lever (2), based on the driving current control
diagram.

The force to move the spools of solenoids A and B is
proportional to the driving current through the coil,
thus the secondary pressure from ports A1 and A2 that
are proportional to the driving current can be output,
as shown in the figure.

T9C812E

860

1500

INPUT CURRENT (AVERAGE)

SECOND

Y PRESSURE

MPa

T9C811E

Solenoid Driving Current

Proportional Signal Input

III-116

MACHINE CONFIGURATION

PROPORTIONAL CONTROL

TB125, 135, 145

P16

P15

T9C813

T9C814

T9C815

The secondary pressure from ports A1 and A2 enters
the pilot port of the control valve [auxiliary] (5) to
control the spool. Therefore, the desired flow rate of
the auxiliary piping can be achieved by operating the
proportional control lever (2) at certain angles.

When button (6) or (7) of the left pilot valve is pressed,
the maximum driving current can be output for the
proportional control solenoid valve (4), despite the
size of the signals input by the proportional control
lever (2). Pressing button (6) outputs the maximum
driving current for solenoid valve A. Pressing button
(7) outputs the maximum driving current for solenoid
valve B. At that time, the flow rate of the auxiliary
piping A or B becomes maximum.

Inspection and Adjustment

Checking the proportional controller

The proportional controller (3) has a built-in fault
detection function, and thus shuts down the solenoid
driving current output by the proportional control
solenoid valve (4) when any of the events described
below is detected. The fault detection function is self-
retained until it is reset at power-up after the error has
been eliminated.
1. Sensor error

The proportional signals are continuously moni-
tored with respect to range. When the signal falls
outside the operating range due to a wire break or
the like, a sensor error is detected. If this occurs,
the “SE” LED on the controller lights up.
• Repair the wiring connected to the propor-

tional control lever (2), or replace the handle
assembly of the pilot valve.

III-117

MACHINE CONFIGURATION

PROPORTIONAL CONTROL

TB125, 135, 145

Monitor terminal Trimmer

Auxiliary piping A
Auxiliary piping B

G-1A

G-1B

P1
P2

T9C816

T9C817

T9C818

2. Neutral error

When the solenoid driving current output by the
proportional control solenoid valve (4) falls out-
side the neutral zone for a certain time (1 second)
after the power is turned on, a neutral error is
detected. If this occurs, the “NE” LED on the
controller lights up.
• Remove any foreign matter from the propor-

tional control lever (2) and clean it, or replace
the handle assembly.

3. Overcurrent

When the driving current output by either sole-
noid valve A or B exceeds the limit due to a short
circuit or the like, an overcurrent error is detected.
If this occurs, the “OL” LED on the controller
lights up.
• Repair the wiring between the controller and

the proportional control solenoid valve A or B.

Adjusting the proportional controller

Although the adjusting trimmer is set for the maxi-
mum flow rate at the factory, the driving current for
the proportional control solenoid valve (4) can be
reduced by using the trimmer. Therefore, the flow rate
can be controlled and the inching of the auxiliary
piping A and B can be improved by dropping the pilot
pressure of the control valve (auxiliary) (5).
1. Turn the starter switch on (ACC), and release the

lever lock condition.

2. While checking the driving current of the propor-

tional control solenoid valve (4) with the voltage
of current monitor terminals G-1A and G-1B,
turn trimmers P1 and P2 anticlockwise to reduce
the driving current.
• The driving current (maximum flow rate) is set

to 1.25 A at the factory.

• The relation between the voltage of the current

monitor terminal and the driving current is 1 V
= 1 A, where the voltage value and current
value are equal.

• The secondary pressure (pilot pressure) of the

proportional control solenoid valve (4) drops
by approximately 0.27 MPa per 0.1 A.

III-118

MACHINE CONFIGURATION

PROPORTIONAL CONTROL

TB125, 135, 145

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-119

TB125, 135, 145

AIR CONDITIONER SYSTEM

CONSTRUCTION

■

TB135: S/N 13510004~13514050

Compressor Assembly

1. Bracket
2. Support
3. Shaft
4. Pulley
5. Bracket
6. Guard

7. Collar
8. Adjuster
9. Pulley
10. Belt
11. Compressor

A: Allow a clearance.
B: Press on the center of the belt with a finger. The belt’s

tension is normal if it bends about 8 mm when pressed
with a force of about 98N.

54.9 N·m

19.6 N·m

Apply thread-locking compound.

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-120

TB125, 135, 145

Condenser Assembly

1. Bracket
2. Bracket
3. Bracket

4. Bracket
5. Hose
6. Hose

7. Hose
8. Presser Switch
9. Condenser

10. Dryer

Air Conditioner Unit (1/2)

1. Cover

2. Louver

3. Cover

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-121

TB125, 135, 145

Air Conditioner Unit (2/2)

1. Air Conditioner Unit

3. Hose

Defroster Assembly

1. Cover
2. Duct
3. Connector

4. Control Panel
5. Hose
6. Hose

7. Hose
8. Hose
9. Bracket

2. Hose

4. Wire Harness

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-122

TB125, 135, 145

Air Conditioner Unit, Control Panel

1. Air Conditioner Unit
2. Motor Assembly
3. Thermostat
4. Resistor
5. Core
6. Valve

7. Wire Harness
8. Control Panel
9. Control Cable
10. Switch
11. Rotary Switch

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-123

TB125, 135, 145

■

TB135: S/N 13514051~

Compressor Assembly

1. Bracket
2. Shaft
3. Pulley
4. Bracket
5. Guard

6. Collar
7. Adjuster
8. Pulley
9. Belt
10. Compressor

A: Allow a clearance.
B: Press on the center of the belt with a finger. The belt’s

tension is normal if it bends about 8 mm when pressed
with a force of about 98N.

54.9 N·m

Apply thread-locking compound.

22.5 N·m

19.6 N·m

47.1 N·m

Apply thread-locking compound.

19.6 N·m

Apply thread-locking compound.

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-124

TB125, 135, 145

Condenser Assembly

1. Bracket
2. Bracket
3. Bracket

4. Bracket
5. Hose
6. Hose

7. Hose
8. Presser Switch
9. Condenser

10. Dryer

Air Conditioner Unit (1/2)

1. Cover

2. Louver

3. Cover

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-125

TB125, 135, 145

Air Conditioner Unit (2/2)

1. Air Conditioner Unit
2. Hose

3. Hose
4. Wire Harness

Defroster Assembly

1. Cover
2. Duct Assembly
3. Connector

4. Control Panel
5. Hose
6. Hose

7. Hose
8. Hose
9. Bracket

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-126

TB125, 135, 145

Air Conditioner Unit, Control Panel

1. Air Conditioner Unit
2. Motor Assembly
3. Thermostat
4. Resistor
5. Core
6. Valve

7. Wire Harness
8. Control Panel
9. Control Cable
10. Switch
11. Rotary Switch

MACHINE CONFIGURATION

AIR CONDITIONER SYSTEM

III-127

TB125, 135, 145

■

TB145: S/N 14510004~14511994

Compressor Assembly

A: Allow a clearance.
B: Press on the center of the belt with a finger. The belt’s

tension is normal if it bends about 8 mm when pressed
with a force of about 98N.

54.9 N·m

Apply thread-locking compound.

47.1 N·m

Apply thread-locking compound.

105.8 N·m

1. Engine Foot
2. Shaft
3. Pulley
4. Bracket

5. Compressor
6. Pulley
7. Belt

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