HYDRAULIC TESTING
9-19TX525 Service Manual Rev. 000
The following procedures should be performed with the
vehicle drive tracks off the ground, and then repeated
under normal operating conditions.
1. Lift/support the unit so that both tracks are off the
ground and free to rotate. Refer to “Lifting Unit for
Service” on page 7-1.
2. Start the engine and run it at slow idle engine speed
for about 20 seconds.
3. Push the traction control to the full forward position
and hold. The tracks should begin to slowly rotate.
Once the tracks begin to rotate smoothly, run for 20
more seconds. Pull the traction control to the full
reverse position and hold. Again, the tracks should
begin to slowly rotate in reverse. Once the tracks
begin to rotate smoothly, allow to run for 30 more
seconds.
4. Raise and lower the loader arm 4 complete cycles.
Raise the loader arm and put it into the oat position.
The loader arm should drop.
5. Cycle the dump cylinder 4 complete cycles.
6. Stop the engine and check the oil level in the
reservoir. Add as necessary.
7. It may be necessary to repeat steps 2 through 6 until
all the air is completely purged from the system.
Due to the effects air has on efciency in hydrostatic
drive applications, it is critical that air is purged from the
system.
These purge procedures should be implemented any-
time a hydrostatic system or hydraulic line has been
opened to facilitate maintenance or any additional oil has
been added to the system.
Air creates inefciency because it has compression and
expansion rates that are higher than that of oil.
Trapped air in the oil may cause the following symptoms:
1. Noisy operation.
2. Lack of power or drive after short-term operation.
3. High oil temperature and excessive expansion of oil.
Before starting, make sure the reservoir is at the proper
oil level. If it is not, ll to the vehicle specications, refer
to the “Hydraulic Reservoir Tank, Checking the Hydraulic
Fluid” section on page 3-4.
Purging Air Procedure
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