Toro 39988 Operator's Manual page 44

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 and set the parking brake.
2. Stop the engine and wait for all moving parts to stop
before leaving the operating position.
3. Raise the rear of the machine up onto jack stands
high enough to raise the drive wheels off the ground.
4. Check the hydraulic fluid level.
5. Start the engine and move the throttle control to the
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 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.
1. Charge pump cap
6. Thoroughly clean the area around each of the charge
pump housings.
7. To prime the charge pump, loosen two hex socket
head capscrews (Figure 56) 1-1/2 turns only. Make
sure engine is not running. Lift charge pump housing
upward and wait for a steady flow of oil to flow out
from under housing. Retighten capscrews. Do this
for both pumps.
Note: Hydraulic reservoir can be pressurized to up
to 5 psi to speed this process.
Figure 56
2. Socket head screw
8. If either drive wheel still does not rotate, stop and
repeat steps 4 and 5 on the respective pump. If
wheels rotate slowly, the system may prime after
additional running. Recheck hydraulic fluid level.
9. Allow unit to run several minutes after the charge
pumps are primed with drive system in the full speed
position.
10. Check the hydro control linkage adjustment. Refer
to Adjusting the Hydro Control Linkages.
Checking the Hydraulic Lines
After every 100 operating hours, check hydraulic
lines and hoses for leaks, loose fittings, kinked lines,
loose mounting supports, wear, weather and chemical
deterioration. Make necessary repairs before operating.
Note: Keep areas around hydraulic system clean from
grass and debris build up.
Hydraulic fluid escaping under pressure can
penetrate skin and cause injury.
• If hydraulic fluid is injected into the skin
it must be surgically removed within a few
hours by a doctor familiar with this type of
injury. Gangrene may result if this is not
done.
• Keep body and hands away from pin hole
leaks or nozzles that eject high pressure
hydraulic fluid.
• Use cardboard or paper to find hydraulic
leaks.
• Safely relieve all pressure in the hydraulic
system before performing any work on the
hydraulic system.
• Make sure all hydraulic fluid hoses and
lines are in good condition and all hydraulic
connections and fittings are tight before
applying pressure to hydraulic system.
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