Purging Procedures - Alamo Bush Hog HDC-3 Series Operator's Manual

6. Repeat steps 1-5 on the opposite side transaxle drive.
7. Drain old oil filters of all free flowing oil prior to disposal.
Place used oil in appropriate containers and deliver to an
approved recycling collection facility.
8. Remove the Top Port Plug from the left side and right
side transaxles prior to filling with oil. This will allow the
transaxles to vent during oil fill.
9. Remove the cap from the transaxle's Oil Reservoir
Tank located on the vehicle frame.
Oil Reservoir Tanks
10. Fill with 20W50 motor oil until oil just appears at the
bottom of each transaxle's top port (approximately 2 qts.
per transaxle, 4 qts. total). Install the top port plug into
each transaxle as the oil level reaches this port.
Note: The oil volume figure shown does not include what
is in the Oil Reservoir Tank hose or the Oil Reservoir
Tank.
11. Install and torque the Top Port Plugs to 180 in. lbs.
(20.3 Nm).
12. Continue to fill the transaxles through the Oil Reser-
voir Tank until the "Full Cold" line is reached on the Hydro-
Gear Oil Reservoir Tank.
HDC-3 ZT 05/19
© 2019 Alamo Group Inc.
MAINTENANCE
Top Port Plug
Maintenance Section 6-12
13. Re-install the Oil Reservoir Tank cap by hand. Be
careful to not overtighten.
14. Proceed to Purging Procedures.

Purging Procedures

These purge procedures should be implemented any
time a hydrostatic system has been opened to facil-
itate maintenance or the oil has been changed.
Due to the effects air has on efficiency in hydrostatic
drive applications, it is critical that it is purged from the
system.
Air creates inefficiency because its compression and ex-
pansion 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 is at the
proper oil level. If it is not, fill to the specifications
outlined in this manual. Refer to steps 10-12 under
Fluid and Filter Change Procedure
The following procedures are best performed with
the vehicle drive wheels off the ground. Then re-
peated under normal operating conditions.
If this is not possible, then the procedure should be
performed in an open area free of any objects or by-
standers.
1. Disengage the brake if activated.
2. With the bypass valve open and the engine running,
slowly move the directional control in both forward and
reverse directions (5 or 6 times).
3. 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.
4. It may be necessary to repeat Steps 2 and 3 until all
the air is completely purged from the system. When the
transaxle operates at normal noise levels and moves
smoothly forward and reverse at normal speeds, then the
transaxle is considered purged.