SANY Crawler Hydraulic Excavator (SY195C9, SY205C9, SY215C9, SY225C9). Shop Manual (2013) - page 24
Troubleshooting
E-24 Incorrect left travel pilot pressure reading
Trouble
Left Travel Pilot Pressure Reading is incorrect.
Related information
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Turn engine start switch to OFF position. Then, keep it at ON position to
Failure of 5V
1
perform troubleshooting.
power supply
Between CN-120M ① and ③
Voltage
About 5V
Ɣ Turn engine start switch to OFF position. Keep it at OFF position to per-
Open circuit of
2
form troubleshooting.
signal wire
Between CN-120M ② and controller pin 49
Resistance
1 ȍ
Ɣ Turn engine start switch to OFF position. Keep it at OFF position to per-
Short circuit of
3
form troubleshooting.
signal wire
Between CN-120M ② and ground
Resistance
2M ȍ
Ɣ Turn engine start switch to OFF position. Then, keep it at ON position to
4
Failure of sensor
perform troubleshooting.
Between CN-120M ② and ground
Voltage
0.5V~ 4.5V
5
CONTROLLER
CN-120M
LEFT TRAVEL PILOT
čDF-3Ď
PRESSURE SENSOR
LEFT TRAVEL PILOT
SIGNAL
49
2
PRESSURE SENSOR
SENSOR GND WIRE
55
3
GND WIRE
SENSOR 5V
75
1
5V
CAB
CHASSIS HARNESS
ZX215-1005115
7-91
Troubleshooting
E-25 Incorrect right travel pilot pressure reading
Trouble
Right travel pilot pressure reading is incorrect.
Related information
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Turn engine start switch to OFF position. Then, keep it at ON position to
Failure of 5V
1
perform troubleshooting.
power supply
Between CN-121M ① and ③
Voltage
About 5V
Ɣ Turn engine start switch to OFF position. Keep it at OFF position to per-
Open circuit of
2
form troubleshooting.
signal wire
Between CN-121M ② and controller pin 67
Resistance
1 ȍ
Ɣ Turn engine start switch to OFF position. Keep it at OFF position to per-
Short circuit of
3
form troubleshooting.
signal wire
Between CN-121M ② and ground
Resistance
2M ȍ
Ɣ Turn engine start switch to OFF position. Then, keep it at ON position to
Failure of sen-
4
perform troubleshooting.
sor
Between CN-121M ② and ground
Voltage
0.5V~ 4.5V
5
CONTROLLER
CN-121M
RIGHT TRAVEL PILOT
čDF-3Ď
PRESSURE SENSOR
RIGHT TRAVEL PILOT
67
2
SIGNAL
PRESSURE SENSOR
55
3
GND WIRE
SENSOR GND WIRE
SENSOR 5V
75
1
5V
CAB
CHASSIS HARNESS
ZX215-1005116
7-92
Troubleshooting
7.7 Troubleshooting of Hydraulic and Mechanical Systems (H - Mode)
A Schematic of hydraulic system and mechanical system
7-94
Information contained in troubleshooting table
7-96
H-1 Work equipment speed slow, or swing and travel speeds slow
7-97
H-2 Engine speed drops sharply or engine stalls
7-98
H-3 Work equipment, swing, and travel systems do not work
7-99
H-4 Abnormal noise in hydraulic pump
7-100
H-5 Auto deceleration not functioning
7-101
H-6 Boom speed slow
7-102
H-7 Arm speed slow
7-103
H-8 Bucket speed slow
7-104
H-9 Work equipment cylinders no response in separate operation
7-105
H-10 Work equipment drifts excessively
7-106
H-11 Work equipment moves sluggishly
7-108
H-12 Other work equipment moves while single oil circuit is relieved
7-108
H-13 Travel speed drops considerably while swinging and travelling
7-109
H-14 Machine deviates during travel
7-110
H-15 Travel speed is low
7-111
H-16 Machine is not steered well or steering power is low
7-112
H-17 Travel speed cannot be changed
7-113
H-18 Travel system fails (only at one side)
7-114
H-19 Swing operation fails
7-115
H-20 Swing acceleration poor or swing speed low
7-117
H-21 Upper structure overruns remarkably when it stops swinging
7-119
H-22 Large shock is produced when upper structure stops swinging
7-120
H-23 High noise is produced when upper structure stops swinging
7-120
H-24 Swing drift excessive
7-121
7-93
Troubleshooting
A Schematic of hydraulic system and mechanical system
PILOT VALVE - L
PILOT VALVE - TRAVEL
PILOT VALVE - R
ARM SWING
TRAVEL
TRAVEL
BOOM BUCKET
(LEFT)
(RIGHT)
LOCK
(PILOT VALVE )
16
BOOM PRIORITY
15
1
2
3
4
5
6
7
8
9
10
11
12
BUCKET CONFLUENCE
14
SWING PRIORITY
13
VARIABLE SPEED
(TRAVEL)
ACCUMULATOR
1
2
3
19
20
17
18
REGULATOR
REGULATOR
SERVO
SERVO
MECHANISM
MECHANISM
P1
P2
M
FRONT
REAR
ZX225-1105039
7-94
Troubleshooting
Ɣ The system schematic is a simplified hydraulic circuit schematic, which can be used as a ref-
erence to the hydraulic system and the mechanical system.
6D
SAFETY VALVE
6X
SUCTION VALVE
6
6
SAFETY&SUCTION
BACKUP VALVE
BUCKET
1
CONFLUENCE
CONFLUENCE
15
1
S&S
ARM VALVE
S&S
ARM 2 VALVE
REG. VALVE
2
1
2
14
BUCKET
CYLINDER
BUCKET
BUCKET
12
BACKUP
S&S
VALVE
S&S
S&S
VALVE
S&S
10
11
BACKUP ACTUATOR
CYLINDER
9
BOOM
BOOM
BOOM 2
9
S&S
VALVE
S&S
10
9
CYLINDER
SWING
MOTOR
13
L. TRAVEL
SWING
5
Su
VALVE
Su
6
3
VALVE
4
13
R. TRAVEL
STRT. TRAVEL
7
Su
VALVE
Su
8
VALVE
TRAVEL
MOTOR (L)
TRAVEL
MOTOR (R)
1
2
3
ZX225-1105040
7-95
Troubleshooting
Information contained in troubleshooting table
Ɣ The following information is contained in the troubleshooting table and related electric circuit diagrams.
Fully understand these information before carrying out troubleshooting.
Trouble
Trouble which occurs on the machine
Related information
Information related to detected trouble or troubleshooting
Cause
Standard value in normal state/Remarks on troubleshooting
1
2
3
Possible causes of
< Description >
trouble (Given numbers
Ɣ Standard value in normal state, which is used to judge possible
are reference numbers,
4
causes that might be OK or N/G.
which do not indicate
Ɣ A reference value is used to determine OK or N/G.
priority)
5
7-96
Troubleshooting
H-1 Work equipment speed slow, or swing and travel speeds slow
Ɣ Work equipment speed is slow or the travel and swing speeds
Trouble
are slow.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running at
high idle.
Defective
adjustment or
Control levers
Main relief pressure
1
malfunction
33~34.3 MPa
of main relief
Arm in
{337~350 kg/cm²}
valve
If normal pressure cannot be restored after adjustment, it is possible the fail-
ure of main relief valve or internal defect. Check the valve directly.
Ɣ Stop the engine. Perform troubleshooting while the engine is running at
high idle.
Malfunction
Control levers
Pilot control pressure
2
of pilot relief
valve
3.9~4.1 MPa
All levers in "NEUTRAL"
{40~42 kg/cm²}
Malfunction of
3
The regulator possibly fails. Check the servo mechanism of the regulator.
regulator
Malfunction of
If the trouble is caused by other factors, it might be the main pump that has
4
main pump
performance deterioration, malfunction or internal defect.
7-97
Troubleshooting
H-2 Engine speed drops sharply or engine stalls
Trouble
Ɣ Engine speed drops sharply or engine stalls.
Related information
Ɣ Information concerned
Cause
Standard value in normal state/Remarks on troubleshooting
1
Failure of injection pump
Injection pump may be defective. Check it directly.
2
Malfunction of regulator
Regulator may have malfunction. Check its servo mechanism.
Clogging of oil filter ele-
3
Oil filter element may be clogged. Check the element directly.
ment
Carbon buildup at fuel
4
Carbon built up at fuel injection nozzle. Check it directly.
injection nozzle
5
Clogging of air cleaner
Air cleaner may be clogged. Check it directly.
6
Abnormal wear of engine
Engine may be worn abnormally. Check it directly.
7
Failure of oil pump
Oil pump may be defective. Check it directly.
7-98
Troubleshooting
H-3 Work equipment, swing, and travel systems do not work
Trouble
Ɣ Whole work equipment, swing, and travel systems do not work.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.
Pilot lockout control lever
Pilot relief pressure
Malfunction of pilot
1
LOCKED
0 {0}
relief solenoid valve
3.9~4.1 MPa
FREE
{40~42 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is run-
ning at high idle.
Failure of relief valve
Control lever
Pilot relief pressure
2
(pilot pump)
3.9~4.1 MPa
All levers in "NEUTRAL"
{40~42 kg/cm²}
The main pump may have malfunction or internal defect. Check it by
Failure of hydraulic
following method.
3
pump
Ɣ Remove the oil pressure measurement plug and start the engine. If
oil flows out of the opening, the piston pump is in good condition.
Internal failure of the coupling can stop rotation of the pump shaft.
Check the coupling.
4
Failure of coupling
Ɣ Loosen the oil delivery line of the pilot pump. If no oil is seen, it is
probably the failure of coupling.
7-99
Troubleshooting
H-4 Abnormal noise in hydraulic pump
Trouble
Ɣ Abnormal noise is produced from the hydraulic pump
Related information
ʊ
Cause
Standard value in normal state/Remarks on troubleshooting
Low level of
1
Make a visual check.
hydraulic oil
Inferior hydrau-
2
Hydraulic oil probably contains air. Make a visual check.
lic oil
Clogging of
It is probably the clogging of the vent on top of the hydraulic tank that
3
vent on top of
causes negative pressure in the hydraulic tank. Press the release button of
hydraulic tank
the breather valve to eliminate air. Check again if the noise disappears.
Clogging of
It is probably the clogging of hydraulic tank strainer that causes negative
4
hydraulic tank
pressure in the oil suction line. Make a visual check.
strainer
Failure of main
5
The main pump may have internal defect. Check the main pump.
pump
7-100
Troubleshooting
H-5 Auto deceleration not functioning
Trouble
Ɣ Auto-deceleration is not functioning.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running at high
idle.
Control levers
Pilot valve output pressure
Malfunction
1
"NEUTRAL"
0 {0}
of sensor
3.5~4.1MPa
Operation
{36~42 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is running at high
idle.
Control levers
Pilot valve output pressure
Malfunction
2
"NEUTRAL"
0 {0}
of pilot valve
3.5~4.1MPa
Operation
{36~42 kg/cm²}
Failure of
3
Controller may be defective. Check it directly.
controller
7-101
Troubleshooting
H-6 Boom speed slow
Trouble
Ɣ The boom moves slowly.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running
at high idle.
Malfunction of right
Boom control lever
Pilot valve output pressure
1
pilot valve (boom
"NEUTRAL"
0 {0}
circuit)
Boom RAISE
3.5MPa
Boom LOWER
{36 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is running
Failure of pressure
2
at high idle.
sensor
Check the pressure sensor by replacing it with a new one.
Malfunction of boom
3
Spool of boom control valve may have malfunction. Check it directly.
control valve (spool)
Malfunction of boom
Retaining valve of boom control valve may have malfunction. Check the
4
control valve (re-
valve directly.
taining valve)
Malfunction or de-
fective seal of boom
The relief valve and makeup valve in boom control valve may have mal-
5
control valve
function or defective seal. Check the valves directly.
(Relief valve and
makeup valve)
Ɣ Stop the engine. Perform troubleshooting while the engine is running
at high idle.
Charge the bucket with a load of approximate 1260 kg. Cut off the oil
passage to the high-pressure side of the cylinder. Disconnect the cylin-
Failure of boom
6
der from the main valve. Measure the displacement of piston for 15 min-
cylinder
utes after the cylinder becomes stable. If the measured value is greater
than 10 mm, it is deemed that cylinder has a defective seal. For more
information on the measuring procedure refer to "Testing and Adjusting",
"Hydraulic Drift (Work Equipment) - Test".
7-102
Troubleshooting
H-7 Arm speed slow
Trouble
Ɣ The arm moves slowly.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Arm control lever
Pilot valve output pressure
Malfunction of left pilot
1
"NEUTRAL"
0 {0}
valve (arm circuit)
3.5MPa
Arm IN or Arm OUT
{36 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is
2
Failure of pressure sensor
running at high idle.
Check the pressure sensor by replacing it with a new one.
Malfunction of arm control
3
Spool of arm control valve may have malfunction. Check it directly.
valve (spool)
Malfunction of arm control
Regeneration valve of arm control valve may have malfunction.
4
valve (regeneration valve)
Check it directly.
Malfunction or defective
seal of arm control valve
The relief valve or makeup valve inside the arm control valve may
5
(Relief valve and makeup
have malfunction or defective seal. Check the valves directly.
valve)
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Cut off the oil passage to the high-pressure side of the cylinder.
Disconnect the cylinder from the main valve. Measure the displace-
6
Failure of arm cylinder
ment of piston for 15 minutes after the cylinder becomes stable. If
the measured value is greater than 10 mm, it is deemed that cyl-
inder has a defective seal. For more information on the measuring
procedure refer to "Testing and Adjusting", "Hydraulic Drift (Work
Equipment) - Test".
7-103
Troubleshooting
H-8 Bucket speed slow
Trouble
Ɣ The bucket moves slowly.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running
at high idle.
Malfunction of right
Bucket control lever
Pilot valve output pressure
1
pilot valve (bucket
"NEUTRAL"
0 {0}
circuit)
3.5MPa
Bucket CURL or Bucket DUMP
{36 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is running
Failure of pressure
2
at high idle.
sensor
Check the pressure sensor by replacing it with a new one.
Malfunction of
3
bucket control valve
Spool of bucket control valve may have malfunction. Check it directly.
(spool)
Malfunction or
defective seal of
Relief valve and makeup valve in bucket control valve may have mal-
4
bucket control valve
function or defective seal. Check the valves directly.
(relief valve and
makeup valve)
Ɣ Stop the engine. Perform troubleshooting while the engine is running
at high idle.
Charge the bucket with a load of approximate 1260 kg. Cut off the oil
passage to the high-pressure side of the cylinder. Disconnect the cylin-
Failure of bucket
5
der from the main valve. Measure the displacement of piston for 15 min-
cylinder
utes after the cylinder becomes stable. If the measured value is greater
than 10 mm, it is deemed that cylinder has a defective seal. For more
information on the measuring procedure refer to "Testing and Adjusting",
"Hydraulic Drift (Work Equipment) - Test".
7-104
Troubleshooting
H-9 Work equipment cylinders no response in separate operation
Ɣ Boom cylinder gives no response in separate operation.
Trouble
Ɣ Arm cylinder gives no response in separate operation.
Ɣ Bucket cylinder gives no response in separate operation.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Work equipment control lever
Pilot valve output pressure
1
Malfunction of pilot valve
"NEUTRAL"
0 {0}
3.5MPa
DIG or DUMP
{36 kg/cm²}
Ɣ Stop the engine. Perform troubleshooting while the engine is
Failure of pressure sen-
2
running at high idle.
sor
Check the pressure sensor by replacing it with a new one.
Malfunction of control
3
Spool of control valve may have malfunction. Check it directly.
valve (spool)
7-105
Troubleshooting
H-10 Work equipment drifts excessively
Trouble (1)
Ɣ The boom drifts at excessive speed.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Charge the bucket with a load of approximate 1260 kg. Cut off the
oil passage to the high-pressure side of the cylinder. Disconnect the
1
Failure of boom cylinder
cylinder from the main valve. Measure the displacement of piston
for 15 minutes after the cylinder becomes stable. If the measured
value is greater than 10 mm, it is deemed that cylinder has a defec-
tive seal. For more information on the measuring procedure refer to
"Testing and Adjusting", "Hydraulic Drift (Work Equipment) - Test".
Failure of boom retain-
Boom retaining valve or pilot valve may be worn or sluggish. Check
2
ing valve
the valves.
Malfunction or defective
seal of boom control
The relief valve and the makeup valve in the boom control valve
3
valve (relief valve and
may have a defective seal. Check the seals.
makeup valve)
Failure of boom valve
4
Spool of boom valve may be worn excessively. Check the spool.
spool
7-106
Troubleshooting
Trouble (2)
Ɣ The arm drifts excessively.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running at
high idle.
Cut off the oil passage to the high-pressure side of the cylinder. Disconnect
Failure of arm
the cylinder from the main valve. Measure the displacement of piston for 15
1
cylinder
minutes after the cylinder becomes stable. If the measured value is greater
than 10 mm, it is deemed that cylinder has a defective seal. For more infor-
mation on the measuring procedure refer to "Testing and Adjusting", "Hy-
draulic Drift (Work Equipment) - Test".
Malfunction or
Relief valve or makeup valve of the arm control valve may be defective.
defective seal of
Check the valves directly.
2
arm control valve
Ɣ The performance of seal can be judged by replacing it with another re-
(relief valve and
lief valve or makeup valve.
(Do not replace it with the boom-down relief
makeup valve)
valve or makeup valve as their pressures are set differently.)
Failure of arm
Arm retaining valve or pilot valve may be worn or sluggish. Check the
3
retaining valve
valves.
Failure of arm
4
Arm valve (spool) may be worn excessively. Check it directly.
valve (spool)
Trouble (3)
Ɣ The bucket drifts excessively.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is running
at high idle.
Failure of bucket
1
Bucket control lever
Leakage from bucket cylinder
cylinder
Bucket-in relief
20 ml/min
Seal of relief valve or makeup valve of bucket control valve may be defec-
Defective seal
tive. Check it directly.
of bucket control
2
Ɣ The performance of seal can be judged by replacing it with another
valve (relief valve
relief valve or makeup valve.
(Do not replace it with the boom-down
and makeup valve)
relief valve or makeup valve as their pressures are set differently.)
Defective seal
3
of bucket control
Seal of bucket control valve spool may be defective. Check it directly.
valve (spool)
7-107
Troubleshooting
H-11 Work equipment moves sluggishly
Trouble
Ɣ Work equipment moves sluggishly.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Malfunction of arm
1
Regeneration valve of arm may have malfunction. Check it directly.
regeneration valve
Relief valve or makeup valve of control valve may have malfunction.
Malfunction of
Check it directly.
control valve (relief
Ɣ For arm and boom, whether a valve has malfunction can be judged
2
valve and makeup
by replacing it with another relief valve or makeup valve.
valve)
(Do not replace it with the boom-lower relief valve or makeup valve as
their pressures are set differently. )
H-12 Other work equipment moves while single oil circuit is relieved
Ɣ Other work equipment moves while single oil circuit of certain work equip-
Trouble
ment is relieved.
Related information
Ɣ Set the working mode to (S) in order to perform troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Defective seal of
1
Seal of control valve may be defective. Check it directly.
control valve
7-108
Troubleshooting
H-13 Travel speed drops considerably while swinging and travelling
Trouble
Ɣ Travel speed drops considerably in swinging plus travelling operation.
Ɣ If the travel speed is low in only travelling operation, check first ac-
Related information
cording to H-15.
Cause
Standard value in normal state/Remarks on troubleshooting
Failure of straight
The straight travel valve gives no response. Check the spool and the
1
travel valve
logic oil circuit drain port.
7-109
Troubleshooting
H-14 Machine deviates during travel
Trouble
Ɣ Machine deviates during travel.
Ɣ Set working mode to (S) and fuel control dial at position (10) to
Related information
carry out troubleshooting.
Cause
Standard value in normal state/Remarks on troubleshooting
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Travel control lever
Pilot valve output pressure
Malfunction of travel pilot
1
Forward
3.5~3.9 MPa
valve
Reverse
{ 36~40 kg/cm²}
Difference occurs between
0.4 MPa {4 kg/cm²}
left and right output
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Malfunction of pilot relief
2
Control lever
Control circuit source pressure
valve
3.5~3.9 MPa
All levers in "NEUTRAL"
{ 36~40 kg/cm²}
3
Failure of regulator
Check the regulator by swapping the front and back regulators.
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Sluggishness of proportion-
4
al solenoid valve
Travel control lever
Proportional valve output pressure
Operate both control levers
0.1 MPa
Sluggishness of travel con-
5
Check the valve spool to see whether it works well.
trol valve (spool)
Internal leakage of central
6
Check it by swapping the lines.
swivel joint
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
7
Malfunction of travel motor
Travel control lever
Leakage of travel motor
Travel relief
27.2 ml/min
Final drive may have internal defect. Check it directly.
Ɣ Internal defect of the final drive can be determined through
8
Failure of final drive
abnormal noise, abnormal heat, and metal powder or debris
contained in the oil drained.
Ɣ Stop the engine. Perform troubleshooting while the engine is
running at high idle.
Travel control lever
Pilot valve output pressure
Failure of travel pilot pres-
Forward
3.5~3.9MPa
9
sure sensor
Reverse
{ 36~40 kg/cm²}
Difference occurs between
0.4 MPa {4 kg/cm²}
left and right output
Check the sensor by swapping it with another one.
7-110