14
-1500/-1700 IHT
PURGING PROCEDURES
Due to the effects air has on ef
fi
ciency in hy-
dro stat ic drive applications, it is critical that it
be purged from the system.
These purge procedures should be im ple -
ment ed any time a hydrostatic system has
been opened to facilitate maintenance or any
additional oil has been added to the system.
Air creates inef
fi
ciency because its com pres -
sion and ex pan sion rate is higher than that of
the oil normally 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-
er a tion
3. High operation temperature and ex ces sive
ex pan sion of "oil", in the latter case, oil may
over
fl
ow.
Before starting, make sure the transaxle/ trans-
mis sion is at the proper oil level. If it is not,
fi
ll
to the manufacturers sug ges tions outlined in
the vehicle owners manual.
The following procedures should be per-
formed with the ve hi cle drive wheels off
the ground, then repeated under normal
op er at ing conditions.
1. With the bypass valve open and the engine
run ning, slowly move the directional control
in both forward and reverse directions 6 to
10 times, as air is purged from the unit, the
oil level will drop and bubbles may ap pear in
the oil. After stopping the engine, add oil, as
nec es sary. Fill to the level out lined in Figure
7, Page 11.
2. With the bypass valve closed and the engine
run ning, slow ly move the directional control
in both forward and reverse directions (6 to
10 times). Check the oil level, and add oil
as re quired 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 for ward
and reverse, purging is complete.
CAUTION
DO NOT OVERFILL.
If you over
fi
ll the transaxle while the unit
is "cold", it may over
fl
ow as it reaches
normal op er at ing tem per a tures. The
oil level should not be above the level
shown in
fi
gure 7, Page 11. This will al low
the space need ed for the oil to ex pand
as it warms up.
