125816 4-9 REV B
Test Procedure for DDC20 Pump
Equipment Required
Hustler
®
Pressure Test Gauge Kit, part number 007898
Pump Test Procedure:
The drive system of this mower consists of two
independent pump/motor combinations and will need to be
tested separately. The oil supply (reservoir), filtering system
(located in the bottom of the reservoir) and oil cooler are
shared between the two independent systems. The testing
sequence below is testing the hydrostatic pumps (only). If
the test shows satisfactory results but performance is still
deemed unacceptable, the motors, filtering, oil cooler and
reservoir should be inspected.
1. Raise the rear of the mower and block with certified
jack stands. The rear wheels need to be able to rotate
freely and clear of all obstructions.
2. Chock the front tires.
3. Raise the seat platform and disconnect the mower
harness from the seat switch. Bypass the seat switch
by connecting the two mower harness female spade
connectors together. Figure 4-21
NOTE: Remove the tire and wheel assembly.
4. Clean hydraulic oil lines connecting to motor
thoroughly. (Contamination allowed to enter in the
hydrostatic system can cause pump and motor
failures).
5. After cleaning, remove oil supply lines from the motor
and loosen supply lines at the pump. One wheel motor
fitting may need to be removed to assist with test line
installation. Cap the wheel motor ports or fittings.
6. Test procedures are the same for both the right and
left sides.
7. Install Hustler
®
Test Gauge Kit (p/n 007898) as shown
in Figure 4-22 and Figure 4-23. Check the bypass valve
(tow valve) to make sure it is fully seated. Figure 4-24
8. Recheck hose and fittings to make sure they are tight.
9. Check oil reservoir for proper oil level and make sure
hydraulic filter is in good condition.
10. Run engine at mid throttle for one or two minutes or
until top of pump is warm to the touch.
11. Increase engine speed to full throttle.
12. Slowly move the steering control lever forward. You
should easily get a 2600 PSI reading from one of the
gauges. Return steering control lever to neutral.
(Caution: Do not hold steering control lever in forward
position for more than 10 seconds as oil will become
extremely hot).
Then, slowly move steering control lever in reverse.
You should easily get a 2600 PSI reading from the
other gauge.
This procedure will require that the unit to be
raised and blocked up off of the ground. It is
necessary for the wheels to rotate without coming
in contact with the floor or any object that would
permit the unit to propel itself. Stay clear and
exercise caution when rotating wheels to prevent
injury. Use only appropriate vehicle 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.
Untrained service personnel should never attempt
to make any adjustments or repairs to the mower’s
drive system while the engine is running. The
following procedures should be performed by trained
service personnel only.
A. Seat switch
B. Female spade connectors
C. Mower harness
Figure 4-21
Hydraulic fluid escaping under pressure may have
sufficient force to penetrate skin and cause serious
injury. Foreign fluid injected into the skin must be
surgically removed within a few hours by a doctor,
familiar with this form of injury, or gangrene may
result.
Before applying pressure to hydraulic system, make
sure all connections are tight and all hoses and lines
are in good condition. To find a leak under pressure,
use a piece of cardboard or wood — never use your
hands. Relieve all pressure in the system before
disconnecting or working on hydraulic lines. To
relieve pressure, lower all attachments and shut off
engine.
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