Service Manual

18 P Series
SECTION 4. SERVICE AND MAINTENANCE
NOTE: Any servicing dealer attempting a
warranty repair must have prior approval
before conducting maintenance of a
Hydro-Gear product, unless the servicing
dealer is a current authorized Hydro-Gear
Service Center.
EXTERNAL MAINTENANCE
Regular external maintenance of a P Series Pump
should include the following:
1. Check the vehicle operator’s manual for
the recommended load ratings. Insure the
current application does not exceed load
rating.
2. Check uid level in reservoir in accordance with
vehicle manufacturer’s recommendations.
NOTE: After the oil has been drained
and maintenance has been performed,
clean oil should be poured directly into
the pump inlet and high pressure ports
prior to plumbing connections and pump
start-up.
3. Inspect the vehicle drive belt, idler pulley(s), and
idler spring(s). Insure that belt slippage is not
causing low input rpm to the pump.
4. Inspect all external plumbing for possible leaks
or loose ttings. An air leak may be difcult to
detect on the “suction side” or inlet line to the
pump. Refer to Purging Procedures page 18.
5. Insure correct inlet lter(s) has been installed
in accordance with the vehicle manufacturer
recommendations.
6. Insure the reservoir is free of contaminants and
is properly vented.
7. Inspect the P Series Pump cooling fan (if
applicable) for broken or distorted blades and
remove any obstructions (grass clippings,
leaves or dirt). Inspect oil cooler (if applicable)
for damaged ns and debris.
8. Inspect the vehicle control linkage to the
directional control arm on the P Series Pump.
Also, insure the control arm is securely fastened
to the trunnion arm.
9. Inspect the bypass on the P Series Pump to
insure it is properly engaged for operation. If
the bypass is not fully engaged (rotated fully
clockwise) it will not function properly. For
vehicle movement without engine power, the
bypass may be backed out (2) turns maximum.
This is only recommended for movement of
short distances at low speeds.
WARNING
Loosening the bypass will result in loss
of hydraulic braking capability.
SERVICE AND MAINTENANCE
PROCEDURES
NOTE: Damage to P Series Pumps may
result from external or internal contami-
nation, heat from excess debris or lack
of lubrication and over-pressurization
of the hydrostatic system. Follow guide-
lines established in this manual and the
vehicle manufacturer’s recommenda-
tions.
All the service procedures presented on the fol-
lowing pages can be performed while the P Series
Pump is mounted on the vehicle. Any servicing
beyond those presented in this section must be
performed after the pump has been removed from
the vehicle.
FLUIDS
The uids used in Hydro-Gear products have been
carefully selected, and only equivalent, or better
products should be substituted.
Typically, an engine oil with a minimum rating of 55
SUS (9.0 cSt) at 230
°
F (110° C) maximum operat-
ing temperature and an API classication of SJ/CD
is allowed. Refer to the vehicle manufacturer for
recommended oil.