Maintenance
Note: Do Not change hydraulic system oil (except for what can be drained when changing filter), unless it is felt the oil has been contaminated or been extremely hot.
Changing oil unnecessarily could damage hydraulic system by introducing contaminates into the system.
Hydraulic System Air Purge
Service Interval: As required
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 (Figure 15). Air in other parts of the hydraulic system will be purged through normal operation once the charge pump is “primed”.
Figure 15
1. Charge pump cap | 2. Loosen 1 1/2 turns only |
1.Stop engine and wait for all moving parts to stop. Raise the rear of the machine up onto jack stands high enough to raise the drive wheels off the ground.
2.Check oil level as stated in Check Hydraulic Oil Level section.
3.Start engine and move throttle control ahead to full throttle position. Move the speed control lever to the middle speed position and place the drive levers in 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 position.
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 with step 4.
4.Thoroughly clean the area around each of the charge pump housings.
5.To “prime” charge pump, loosen two hex socket head capscrews (shown in Figure 15) 1 1/2 turns only. Make sure engine is not running. Lift the charge pump housing upward and wait for a steady flow of oil to flow out from under the housing. Retighten the capscrews. Do this for both pumps.
Note: Hydraulic reservoir can be pressurized up to 5 psi to speed this process.
6.If either drive wheel still does not rotate, stop and repeat steps 4 and 5 above for the respective pump. If wheels rotate slowly, the system may prime after additional running. Check oil level as stated in Check the Hydraulic Oil Level section.
7.Allow unit to run several minutes after the charge pumps are “primed” with drive system in the full speed position. Check oil level as stated in Check the Hydraulic Oil Level section.
8.Check hydro drive linkage adjustment as stated in Hydro Drive Linkage Adjustment section in Adjustments.
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