Air Purging Procedure; Hydro Transaxle Replacement - Toro TIMECUTTER 74685 Service Manual

Air Purging Procedure

Hydro Transaxle Replacement

Hydro Transaxle Removal
Hydrostatic Drive System: Service and Repairs
Due to the effects air has on efficiency in hydrostatic drive applications, it
is critical that it is purged from the system. These purge procedures should
be implemented any time a hydrostatic system has been opened to facilitate
maintenance or any additional oil has been added to the system.
The following procedures should be performed with the vehicle drive wheels off
the ground, then repeated under normal operating conditions Before starting,
make sure the transaxle/transmission is at the proper oil level.
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 forward and reverse at
normal speed purging is complete.
1. Park the machine on a level surface and set the parking brake. Stop the
engine, wait for all moving parts to stop and remove the key.
2. Disconnect the battery by removing the negative battery cable first, then
the positive cable from the battery.
3. Using an appropriate lifting device, raise the rear of the machine.
4. Remove the 13/16 inch lug nut securing the wheel to the transaxle hub.
5. Remove the wheel from the transaxle hub.
6. Remove the cotter pin and washer securing the dump valve rod to the
transaxle. Remove the dump valve rod linkage from the transaxle.
g302067
Figure 236
Page 6–12 TIMECUTTER® Service Manual
3433-938 Rev A