Service manual
115615 4-7 REV C
wheel motor load.
Installation & Testing Procedures
Disconnect the system hoses at the wheel motor, or system
hoses from the pump and connect the Bi-Directional Flow Test
Kit. (Special care should be taken to prevent contamination
debris from entering pump or wheel motor system ports).
NOTE: Using the Bi-Directional Flow Test Kit, determina-
tion of directional flow is not necessary. The flow meter may be
connected in either direction into the forward and reverse high
pressure system lines.
NOTE: The following adapter fittings will be required when
connecting the Bi-Directional Test Kit (Excel P/N 783886 or
Hydro-Gear P/N 70661):
PY (21) Series Pumps require two 771311 adapter
fittings.
CAUTION: Ensure all fittings and hoses are attached
securely. This test is being completed on the vehicle’s high pres-
sure system lines. Failure to perform this properly could result
in bodily injury.
Testing Procedures
1. Use approved jack stands to raise the drive wheels off the
floor.
2. Open the restriction valve all the way.
3. Increase the engine rpms until a maximum of 15 gpm
shows on the Flow Test Kit gauge.
CAUTION: Damage to the flow meter and/or re-
calibration may result from testing at input speeds that
exceed the above recommendations.
4. For the pump being tested, move the steering control
levers in full forward motion. (It will be necessary to lock
the steering control levers into full forward position to
prevent false readings).
5. Operate without any load for approximately 30 seconds
to 1 minute. This allows the system oil temperature to
rise.
NOTE: Raising the system oil temperature will make a
difference in the readings you receive. It has been
determined that to complete this test accurately, the oil
temperature must be near system operating temperatures.
Suggested temperature range 160° - 210° F (71.1° - 98.9°
C)
6. Tighten the flow meter restriction valve until the gauge
reads 300 psi (21 bar).
Record the flow reading on the Bi-Directional Flow
Meter.
7. Increase the pressure to 1100 PSI (76 bar).
Record the flow reading on the Bi-Directional Flow
Meter.
8. The acceptable gpm “flow droop” or (difference) is:
If the difference exceeds these values the pump would
not be operating efficiently and should be replaced or
repaired. See the following example.
WARNING
Certain procedures require the vehicle engine to be
operated and the vehicle to be raised off of the ground.
To prevent possible injury to the servicing technician
and/or bystanders, insure the vehicle is properly
secured.
WARNING
Do not attempt any adjustments with the engine run-
ning. Use extreme caution while working in or around
all vehicle linkage! High temperatures can be gener-
ated. Follow all safety procedures outlined in the vehi-
cle owner’s manual!
WARNING
Never work under the machine or attachment unless it is
safely supported with jack stands. Make certain machine
is secure when it is raised and placed on the jack stands.
The jack stands should not allow the machine to move
when the engine is running and the drive wheels are rotat-
ing. Use only certified jack stands. Use only appropriate
jack stands, with a minimum weight rating of 2000
pounds to block the unit up. Use in pairs only. Follow the
instructions supplied with the vehicle stands.
PY (21) 2.5 gpm (9.4 l/min)