Jacobsen AR3, Technical/Repair Manual

Page: 224 / 342

HYDRAULICS
4181384 First Edition 6-33
6
Mow/Brake Valve Tests
See Figures 6-25 and 6-26.
!
WARNING
1. Park the mower safely. (See “Park Mower Safely” on
page 1-7.)
2. Before performing this test, perform cutting unit
system test leaving flow meter connected as
outlined.
3. Raise seat platform.
4. Bypass seat switch.
Figure 6-25
5. Install blocking disk at fitting (1) on mow/brake valve,
blocking oil flow from entering left front cutting unit
motor.
Figure 6-26
6. Open flow meter valve (2) completely.
Verify engine rpm is within specification (3150 rpm ± 50)
to ensure accurate hydraulic test results.
7. Start engine and run at full throttle (3150 rpm ± 50).
8. Use the flow meter to warm the hydraulic oil. Turn the
flow meter valve (2) until a reading of 1525 psi (105
bar) or one half of the relief valve rating is reached.
Warm oil to 120—150°F (49—65°C), open valve fully
after operating temperature is reached.
9. Engage cutting unit switch.
10. Slowly close flow meter valve (2) until pressure
reaches 2300 psi (159 bar). Read and record the
cutting unit/charge pump loaded flow.
11. Calculate mow/brake valve leakage.
(Step 15 of previous test – Step 10 / Step 15 of
previous test x 100 = Leak Percentage)
Is mow/brake valve leakage 10% or less?
YES The mow/brake valve is good. Proceed to
step 12.
NO Proceed to next question.
Is mow/brake valve leakage 11% to 20%?
YES The mow/brake valve is marginal. Additional
testing is required.
NO Proceed to next question.
Is mow/brake valve leakage 21% or more?
YES Replace mow/brake valve. (See “Mow/Brake
Valve” on page 6-50.)
The hydraulic system is under pressure, and the
oil will be hot.
• Always relieve pressure in the hydraulic
system before performing service.
• Failure to follow appropriate safety
precautions may result in death or serious
injury.
Required Tools and Materials
• Flow Meter
• Test Hose 4000 psi (276 bar)
• Tee Fitting
• Blocking Disk
TN1362
1
TN1363
2