Service Manual

12 ZT-2100 / ZT-2200 (EZT
®
)
PURGING PROCEDURES
Due to the effects air has on efciency in hy-
drostatic drive applications, it is critical that it is
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 inefciency 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 op-
eration.
3. High operation temperature and excessive
expansion of oil.
Before starting, make sure the transaxle/trans-
mission is at the proper oil level. If it is not,
ll to the specications outlined on Page 11,
Figure 4.
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 or
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 forward and reverse directions (5 to
6 times). Check the oil level, and add oil as
required after stopping the 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 for-
ward and reverse at normal speed purging
is complete.