Maeda MC815C - Steering Is Difficult or Weak; Travelling Rubber Track Fails to Move (One Side Only; Travelling Speed Cannot be Changed, or Travelling Speed Is Slow;High

T-426
H-21 [Steering is difficult or weak]
Content Steering is difficult or weak
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Malfunction of travel /
outrigger control valve
★ Stop engine to perform preparations and conduct diagnosis at a
high engine idling speed.
Travel lever at neutral
Output pressure: 0 Mpa [0 kg/cm
2
]
Travel lever during operation
Pilot pressure: 3.1 Mpa [32 kg/cm
2
] or more
Max. operating pressure: 24.5 Mpa [250 kg/cm
2
]
•
Check travelling operation pilot pressure is normal
• Check operating pressure for travelling operation is normal
2
Operation fault of hydraulic
pump
Check for hydraulic pump malfunctions / seal failures
3
Travel operation valve
(spool) operation fault
• Check for malfunction of travelling operation valve spool
4
2-speed travelling switching
solenoid is defective
• Check if 2-speed travelling switching solenoid (travel speed
switching valve) functions properly
5
Operation fault of travel
motor
Check for travelling motor operation faults
(It may be determined by switching between forward and backward
rotational direction of the same motor or between left and right
motors.)
H-22 [Travelling speed cannot be changed, or travelling speed is slow/high]
Content Travelling speed cannot be changed, or travelling speed is slow/high
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Travelling 2-speed switching
solenoid malfunction
★ Stop engine to perform preparations and conduct diagnosis at a
high engine idling speed.
Travelling speed, travel lever: Lo (position 1) or at neutral
Output pressure: 0 Mpa [0 kg/cm
2
]
Travelling speed, travel lever: Hi (position 2) or during operation
Output pressure: 3.1 Mpa [32 kg/cm
2
]
2
Operation fault of travel
motor (speed changing
section)
Check for malfunction in the travelling motor speed changing
section
H-23 [Travelling rubber track fails to move (one side only)]
Content Travelling rubber track fails to move (one side only)
Assumed cause
and action to be
taken
Cause Diagnostic method and action to be taken
1
Malfunction of travel /
outrigger control valve
★ Stop engine to perform preparations and conduct diagnosis at a
high engine idling speed.
Travel lever at neutral
Output pressure: 0 Mpa [0 kg/cm
2
]
Travel lever during operation
Pilot pressure: 3.1 Mpa [32 kg/cm
2
] or more
Max. operating pressure: 24.5 Mpa [250 kg/cm
2
]
•
Check travelling operation pilot pressure is normal
• Check operating pressure for travelling operation is normal
2 Malfunction of travel motor
★ Stop engine to perform preparations and conduct diagnosis at a
high engine idling speed.
Travel lever during travel relieving
Travelling motor leakage amount: 1.65 L/min
Check for travelling motor operation faults
(It may be determined by switching between forward and backward
rotational direction of the same motor or between left and right
motors.)
(Assess by presence of abnormal sounds or heating, metal powder
contamination in drain oil, etc.)