Service Manual

Mid-Size Walk Behind Service Manual 5 - 5
HYDRAULIC DRIVE SYSTEMS
Bleeding Hydraulic System (Fixed Deck Models)
The traction system is self-bleeding, however, it may
be necessary to bleed the system if fluid is changed or
after work is performed on the system.
Air must be purged from the hydraulic system when
any hydraulic components, including oil filter, are
removed or any of the hydraulic lines are disconnected.
The critical area for purging air from the hydraulic
system is between the oil reservoir and each charge
pump located on the top of each variable displacement
pump. Air in other parts of the hydraulic system will be
purged through normal operation once the charge
pump is “primed”.
1. Disengage the PTO, turn the ignition key to off,
and remove the key. Wait for all moving parts to
stop before leaving the operating position.
2. Raise the rear of machine so wheels are off the
ground and support with jack stands.
3. Check hydraulic fluid level.
4. Start engine and move throttle control to full
throttle position. Move the speed control lever to
the middle speed position and place the drive
levers into the “drive” position.
If either drive wheel does not rotate, it is possible to
assist the purging of the charge pump by carefully
rotating the tire in the forward direction.
Note: It is necessary to lightly touch the charge pump
cap (Figure 76) with your hand to check the pump
temperature. If the cap is too hot to touch, turn off
engine. The pumps may be damaged if the pump
becomes too hot. If either drive wheel still does not
rotate, continue to next step.
Figure 76
m-5955
(1) Charge pump cap (2) Socket head screw