Jacobsen AR3, Техническое руководство по ремонту

Страница: 220 / 342

HYDRAULICS
4181384 First Edition 6-29
6
3. Remove both hydraulic hoses from the steering
cylinder, plug the hoses and cap the cylinder ports.
4. Turn the steering wheel all the way to the right and
then all the way 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 7-10.)
With steady pressure in one direction, does
steering wheel make one complete revolution in
30 seconds?
YES Steering valve faulty, repair or replace as
needed. (See “Steering Valve” on page 7-7.)
Cutting Unit Motor Test
The deck motor circuit consists of the cutting unit/charge
pump, mow valve, and cutting unit motors. This test
determines if one of the cutting unit motors are faulty. An
instrument test must be performed to isolate the
performance of the charge pump and mow valve.
NOTES
• Perform test on only one cutting unit motor at a time.
• The case drain on a hydraulic motor is used to return
excess 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. Remove the case drain hose from the cutting unit
motor. Immediately plug the hose.
4. Position a drain pan (minimum capacity 1 gallon
(3.8 L) near the cutting unit motor.
5. Install a separate hose on the case drain fitting and
place the free end in the container.
6. Install a blocking disk or plug and cap on the motor
return hose and motor port, to block the oil flow. This
allows oil pressure to build in the motor being tested.
7. Chock the wheels so the machine cannot roll.
8. Set the parking brake, start the engine, release the
parking brake, and place the mow switch in the on
position for 15 seconds.
9. Stop the engine and remove the ignition key.
10. 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 Procedures” on page 6-29.)
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 “Cutting Unit Motor” on
page 6-46.)
11. Remove the test hose and all caps and plugs.
Reconnect hydraulic hose to motor.
Instrument Test Procedures
Instrument Test Overview
The following tests are specifically designed to approach
hydraulic testing on a system level. Each component
within the system represents a portion of the total system
leakage. An internal leakage percentage for each
component will be calculated and recorded, enabling the
technician to view the system performance issue more
completely. The test results will help the technician to
determine which repairs will best remedy the
performance issue experienced by the machine user.
The internal leakage percentage ranges are as follows:
0—10% = Good
11—20% = Marginal
21% and beyond = Bad
Example: Cutting Unit System Performance
Complaint
The machine operator reports the mower is not cutting
correctly.
Troubleshooting must first be performed to rule out a
cutting unit adjustment issue. Once the issue is known to
be component related, the entire cutting unit system is
tested as outlined. The calculated system leakage is
35%; a result which requires the testing of individual
components. This result can also be interpreted as the
system is 65% efficient.
The remaining components in question are as follows:
cutting unit/charge pump, mow/brake valve, left cutting
unit motor, right cutting unit motor, and center rear cutting
unit motor. Following the procedures as outlined, test
each individual component, then calculate and record
leakage percentages.