SANY Crawler Hydraulic Excavator SY215CLC (CUMMINS QSB6.7 engine). Shop Manual

Testing and Adjusting

SY215C

6-26

6.12

Work Equipment Hydraulic Drift - Test

★

If hydraulic drift exists in the work equip-
ment cylinder, check it according to the
following procedure and determine whether
the failure lies in the cylinder seal or in the
control valve.

1. Boom and bucket cylinders

1) Park your machine in an attitude as

shown and stop the engine.

★

Load the bucket fully with earth or
impose rated load on the bucket.

2) Operate the control levers so that the

boom is in the raising position and the
bucket in the digging position.

●

If the lowering speed increases, the
problem lies in the cylinder seal.

●

If nothing changes, the problem lies in
the control valve.

★

Operate the control levers with engine
start switch in the ON position.

★

If the pressure in accumulator drops,
charge the accumulator again by run-
ning the engine for about 10 seconds.

ZX215-1004033

Testing and Adjusting

SY215C

6-27

2. Arm cylinder

1) Park your machine in an attitude as

shown. The distance between the arm
cylinder and the digging stroke end is
100 mm. Stop the engine.

2) Operate the control levers in order to

place the arm in the digging position.

●

If the lowering speed increases, it is
failure of the cylinder seal.

●

If nothing changes, it is failure of the
control valve.

★

Operate the control levers with engine
start switch in the ON position.

★

If the pressure in accumulator drops,
charge the accumulator again by run-
ning the engine for about 10 seconds.

[Reference]

If the hydraulic drift is caused by failure of the
cylinder seal, the reason for increase of lower-
ing speed during the above operation is de-
scribed below:

1) If the machine is set in the above posi-

tion (where the holding pressure is ap-
plied to the bottom side), the oil leaks
from the bottom side to the head side.
The pressure in the head side is in-
creased.

2) As the pressure in the head side de-

creases, the pressure in the bottom
side increases in order to keep it bal-
anced. This process is repeated until
balance is reached at a certain level
depending on the amount of leakage.

ZX215-1004034

Testing and Adjusting

SY215C

6-28

3) When the pressure is balanced, the

lowering speed decreases. If the con-
trol levers are operated according to
the above procedure, the oil circuit in
the head side opens to the drain circuit
(while the bottom side is closed by a
check valve), and the oil flows to the
drain circuit from the head side. As a
result, the lowering speed increases.

3. Checking the pilot valve

While the pressure in the accumulator is
high, set the hydraulic lockout control in
the LOCKED/FREE position and measure
the hydraulic drift respectively.

★

Operate the control levers with engine
start switch in the ON position.

★

If the pressure in accumulator drops,
charge the accumulator again by run-
ning the engine for about 10 seconds.

★

If there is a difference in hydraulic drift
between the LOCKED position and the
FREE position, it the failure (internal
fault) of the pilot valve.

Testing and Adjusting

SY215C

6-29

6.13

Residual Pressure in Hydraulic Circuit - Release

Before disconnecting the lines between

the hydraulic cylinders or between the
hydraulic motor and the control valve,
perform the following steps in order to
release the residual pressure from the
hydraulic circuit.

★

Even if the swing motor circuit and the
travel motor circuit are free from residual
pressure, they will be influenced by the
internal pressure of hydraulic tank. The
breather valve must therefore be opened
to release pressure prior to such operation.

1. Stop the engine, loosen the butter

y nut on

the breather valve, and press the release
button to release the pressure in hydraulic
tank.

2. Turn the engine start switch to the ON

position and operate the control levers for
several times.

★

The pilot lock valve must be energized.
Operate the control levers with the
engine start switch in the ON position.

★

The pressure in accumulator will be
released after the control levers have
been operated 2 or 3 times.

3. Start the engine and keep the engine

running at low idle for about 10 seconds in
order to increase the pressure in accumu-
lator. Stop the engine.

4. Repeat the above step 2 through step 3

several times.

Testing and Adjusting

SY215C

6-30

6.14 Oil Leakage - Measure

1. Measure oil leakage from boom cylinder

1) Start the engine and keep the engine

running until the hydraulic oil tempera-
ture reaches a point within the opera-
tional range. Fully extend the boom
cylinder.

Release the residual pressure in

the circuits. See “Residual Pres-
sure in Hydraulic Circuit - Re-
lease” on page 6-29.

2) Disconnect the hose (1) on the cylinder

head side and blind the hose end with
a cap.

Be careful not to disconnect the

hose on the cylinder bottom side.

3) Start the engine and apply relief pres-

sure to the bottom side of the cylinder
while the engine is running at high idle.

4) Hold this condition for 30 seconds.

Measure oil leakage for one minute.

5) Make sure that the machine returns to

its normal condition after measurement.

ZXT215-1004010

Testing and Adjusting

SY215C

6-31

2. Measure oil leakage from arm cylinder

1) Start the engine and keep the engine

running until the hydraulic oil tempera-
ture reaches a point within the opera-
tional range. Fully extend the arm cylin-
der.

Release the residual pressure in

the circuits. See “Residual Pres-
sure in Hydraulic Circuit - Re-
lease” on page 6-29.

2) Disconnect the hose (2) on the cylinder

head side and blind the hose end with
a cap.

Be careful not to disconnect the

hose on the cylinder bottom side.

3) Start the engine and apply relief pres-

sure to the bottom side of the cylinder
while the engine is running at high idle.

4) Hold this condition for 30 seconds.

Measure oil leakage for one minute.

5) Make sure that the machine returns to

its normal condition after measurement.

ZXT225-1104007

Testing and Adjusting

SY215C

6-32

3. M e a s u r e o i l l e a k a g e f r o m b u c k e t

cylinder

1) Start the engine and keep the engine

running until the hydraulic oil tempera-
ture reaches a point within the opera-
tional range. Fully extend the bucket
cylinder.

Release the residual pressure in

the circuits. See “Residual Pres-
sure in Hydraulic Circuit - Re-
lease” on page 6-29.

2) Disconnect the hose (3) on the cylinder

head side and blind the hose end with
a cap.

Be careful not to disconnect the

hose on the cylinder bottom side.

3) Start the engine and apply relief pres-

sure to the bottom side of the cylinder
while the engine is running at high idle.

4) Hold this condition for 30 seconds.

Measure oil leakage for one minute.

5) Make sure that the machine returns to

its normal condition after measurement.

ZXT225-1104008

Testing and Adjusting

SY215C

6-33

4. Measure oil leakage from swing motor

1) Fully extend the work equipment. Low-

er the bucket on the ground and raise
the machine slightly. Stop the engine.

2) Disconnect the hose (4) and the hose

(5). Blind the hose ends with caps.

3) Start the engine and apply relief pres-

sure to the bottom side of the cylinder
while the engine is running at high idle.
Measure oil leakage under this condi-
tion.

★

Hold the condition described in step 3)
for 30 seconds. Measure oil leakage for
one minute.

★

After the first measurement, turn the
upper structure 180°and measure the
leakage again in the same way.

4) Make sure that the machine returns to

its normal condition after measurement.

ZXT225-1104006

Testing and Adjusting

SY215C

6-34

5. Measure oil leakage from travel motor

1) Remove the cover of the travel motor.

2) Start the engine and lock the travel

mechanism.

Insert pin (1) between the sprocket

and the track frame to lock the
travel mechanism.

3) Disconnect the drain hose (6) of the

travel motor. Blind the hose end with a
cap.

4) Start the engine and apply relief pres-

sure to the bottom side of the cylinder
while the engine is running at high idle.
Measure oil leakage under this condi-
tion.

During measurement, mis-oper-

ation of the control levers can
cause serious accidents. Make
sure that all signals are correct.

★

Hold the condition described in step 4)
for 30 seconds. Measure oil leakage for
one minute.

★

Rotate the motor slightly. Change the
positions of the valve plate and the
cylinder and of the cylinder and piston.
Repeat the measurement several
times.

5) Make sure that the machine returns to

its normal condition after measurement.

ZXT215-1004014

ZXT215-1004004

Testing and Adjusting

SY215C

6-35

6.15

Air in Each Component - Bleed

Air bleeding item

Contents of work

Air bleeding procedures

Bleed air

from hydrau-

lic pump

Starting

engine

Bleed

air from

cylinder

Bleed air

from swing

motor

Bleed air

form travel

motor

Starting

operation

●

Replacing hydraulic oil

●

Cleaning

lter element

○

(Note)

○

(Note)

○

●

Replacing return

lter element

○

●

Repairing/replacing hydraulic pump

●

Removing suction piping

○

●

Repairing/replacing control valve

○

●

Replacing cylinder

●

Removing cylinder piping

○

●

Replacing swing motor

●

Removing swing motor piping

○

●

Replacing travel motor

●

Removing travel motor piping

○

Note:

Bleed air from the swing motor and travel
motor only when the oil in the motor cases is
drained.

1. Bleed air from hydraulic pump

1) Loosen the air bleeder (1) and check

that oil oozes out through the air bleed-
er.

2) Tighten the air bleeder (1) if oil is seen.

Bleeder:

7.8~9.8 N·m{0.8~1.0 kgf·m}

★

Engine starting precautions

Run the engine at low idle for 10 min-
utes after bleeding the air according to
the above procedure.

ZXT215-1004015

Testing and Adjusting

SY215C

6-36

2. Bleed air from hydraulic cylinder

1) Start the engine and keep the engine

running at low idle for 5 minutes.

2) Raise or lower the boom 4 or 5 times

with the engine running at low idle.

★

Be careful not to apply relief pressure.
Stop the piston when the piston rod is
about 100 mm before stroke end.

3) Repeat step 2) with the engine running

at high idle.

4) While running the engine at low idle,

move the piston rod to the stroke end
and apply relief pressure.

5) Bleed air from arm cylinder and bucket

cylinder by performing step 2) through
step 4).

★

When a new cylinder is installed for
replacement, bleed the air from the
new cylinder before mounting it to the
work equipment. Especially the boom
cylinder, once mounted to the work
equipment, its piston rod is unable
to reach its stroke end in lowering
operation. Therefore, the air must be
bled from the boom cylinder before it is
mounted to the work equipment.

3. Bleed air from swing motor

1) Start the engine and run the engine at

low idle.

2) Bleed air from the swing motor by turn-

ing the upper structure slowly.

Troubleshooting

SY215C

7-3

Stop the machine in a level ground, and

check that lock pins, blocks, and parking
brake are securely

tted.

When carrying out the operation with

two or more workers, keep strictly to the
agreed signals, and do not allow any un-
authorized person to come near.

If the radiator cap is removed when the

engine is hot. Hot coolant may spurt out
and cause burns, so wait for the engine to
cool down before starting troubleshooting.

Be extremely careful not to touch any

hot parts or to get caught in any rotating
parts.

When disconnecting wiring, always dis-

connect the negative (–) terminal of the
battery

rst.

When removing the plug or cap from a

location which is under pressure from oil,
water, or air, always release the internal
pressure

rst. When installing measuring

equipment, be sure to connect it properly.

TROUBLESHOOTING

7.1

Points to Remember When Troubleshooting

The aim of troubleshooting is to pinpoint the
basic cause of the failure, to carry out repairs
swiftly, and to prevent reoccurrence of the fail-
ure.

When carrying out troubleshooting, important
point is to understand the structure and func-
tion.

However, a short cut to effective troubleshoot-
ing is to ask the operator various questions
to form some idea of possible causes of the
failure that would produce the reported symp-
toms.

SANY Crawler Hydraulic Excavator SY215CLC (CUMMINS QSB6.7 engine). Shop Manual - page 23