6-26 4203780 First Edition
HYDRAULICS
6
Power Steering Circuit Test
The purpose of this test is to determine if the steering
cylinder and the steering valve are operating properly.
NOTE
Before performing this test, check the steering system for
mechanical binding or damage that may affect the
steering.
1. Operate the machine until hydraulic oil reaches
operating temperature, 120—150° F (49—65° C).
2. With the engine running, turn the steering wheel all
the way to the right and then all the way to the left.
Does the steering wheel continue to turn after full
left or right movement of the steering cylinder?
YES Proceed to step 3.
NO Steering system is not faulty.
3. Stop the engine and remove both hydraulic hoses
from the steering cylinder; plug the hoses and cap
the cylinder ports.
4. Start the engine and turn the steering wheel all the
way to the right and then all the way to the left. Only a
little movement should be evident.
Is the steering wheel hard to turn or does not
turn?
YES Steering cylinder is faulty; repair or replace
as needed. (See “Steering Cylinder” on
page 7-21.)
With steady pressure in one direction, does
steering wheel make one complete revolution in
30 seconds?
YES Steering valve is faulty; repair or replace as
needed. (See “Steering Valve” on page 7-8.)
Cutting Unit System Test
The cutting unit system consists of three circuits: the front
cutting unit circuit, the left wing cutting unit circuit, and
the right wing cutting unit circuit. The front cutting unit
circuit consists of the front cutting unit pump, front deck
valve, right front cutting unit motor, center front cutting
unit motor, and left front cutting unit motor. The left wing
cutting unit circuit consists of the left wing cutting unit
pump, left deck valve, left wing inside cutting unit motor,
and left wing outside cutting unit motor. The right wing
cutting unit circuit consists of the right wing cutting unit
pump, right deck valve, right wing inside cutting unit
motor, and right wing outside cutting unit motor. This test
determines if one of the cutting unit motors is faulty. An
instrument test must be performed to isolate the
performance of the cutting unit pumps and deck valves.
NOTES
• Perform test on only one cutting unit motor at a time.
• The case drain on a hydraulic motor is used to return
lubrication or bypassed hydraulic oil back to the
hydraulic tank.
1. Operate the machine until hydraulic oil reaches
operating temperature, 120—150° F (49—65° C).
2. Stop the engine and remove the key.
3. Bypass the seat switch.
4. Remove the case drain hose from the cutting unit
motor. Immediately plug the hose.
5. Position a drain pan with a minimum capacity of 1
gallon (3.8 L) near the cutting unit motor.
6. Install a separate hose on the case drain fitting and
place the free end in the container. Secure the hose
to prevent spills.
!
WARNING
7. Install suitable blocking device or tool in cutting unit,
preventing cutting unit from turning.
8. Set the park brake and start the engine.
9. Place the PTO switch in the ON position.
10. Place the mow enable switch in the ON position for
15 seconds.
11. Stop the engine and remove the ignition key.
12. Measure the amount of oil that flowed from the case
drain. The amount x 4 = amount per minute.
Is the oil captured from the case drain within a
half pint per minute?
YES The motor shaft and/or bearings are not
faulty; proceed with an instrument test. (See
“Instrument Test Procedure” on page 6-27.)
Is the oil captured from the case drain more than
1 pint per minute?
YES The motor may be faulty; repair or replace as
needed. (See “Deck Motors” on page 6-61.)
13. Disconnect and remove test equipment. Install all
hoses, fittings, and components as noted prior to
removal.
Safely block cutting unit from rotating using a
suitable device or tool. Failure to follow
appropriate safety precaution may result in death
or serious injury.
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