Purging Procedures - Cub Cadet 900 Series Professional Shop Manual

Due to the effects air has on efficiency in
hydrostatic drive applications, it is critical that it
be purged from the system.
These purge procedures should be imple-
mented any time a hydrostatic system has
been opened to facilitate maintenance or any
additional oil has been added to the system.
Air creates inefficiency because its compres-
sion and expansion rate is higher than that of
the oil approved for use in hydrostatic drive
systems.
The resulting symptoms in hydrostatic systems
may be:
1. Noisy operation.
2. Lack of power or drive after short term
operation.
3. High operation temperature and excessive
expansion of oil.
Before starting, make sure the transaxle/
transmission is at the proper oil level. If it is
not, fill to the specifications outlined on page
10, Figure 4.
310-0510 IHT

PURGING PROCEDURES

The following procedures should be performed
with the vehicle drive wheels off the ground,
then repeated under normal operating condi-
tions.
1. With the bypass valve open and the engine
running, slowly move the directional control
in both forward and reverse directions
(5 to 6 times), as air is purged from the unit,
the oil level will drop.
2. With the bypass valve closed and the
engine running, slowly move the directional
control in both
directions (5 to 6 times). Check the oil level,
and add oil as required after stopping
engine.
3. It may be necessary to repeat Steps 1 and 2
until all the air is completely purged from the
system. When the transaxle moves forward
and reverse at normal speed purging is
complete.
forward and reverse
11