Textron JACOBSEN GP400, Technical/Repair Manual

Page: 161 / 354

HYDROSTATIC POWER TRAIN
4252490-Rev A 5-43
5
Figure 5-37
11. Adjust flow lock tool (11) to allow pump to produce 7
gpm (27 lpm) in the forward direction.
12. Use the flow meter to warm the hydraulic oil. Turn
flow meter valve until a reading of 1000 psi (69 bar)
is reached. Warm the oil to 120–150° F (49–65° C);
open valve fully after operating temperature is
reached.
13. After warming the hydraulic oil, verify flow lock tool is
adjusted to allow pump to produce 7 gpm (27 lpm) in
the forward direction. Read and record no load flow.
14. Slowly close flow meter valve until a reading of
2500 psi (172 bar) is reached. Read and record
loaded flow.
15. Stop engine, apply park brake, and return flow lock
tool to the neutral position.
16. Calculate traction pump leakage.
(Step 13 – Step 14 / Step 13 x 100 = Leak
Percentage)
Is traction pump leakage 10% or less?
YES The traction pump is good. Proceed to
“Wheel Motors Tests” on page 5-43.
NO Proceed to next question.
Is traction pump leakage 11–20%?
YES The traction pump is marginal. Additional
testing is required. Proceed to “Wheel
Motors Tests” on page 5-43.
NO Proceed to next question.
Is traction pump leakage 21% or more?
YES Repair or replace traction pump. See
“Traction Pump and Control” on page 5-50,
then proceed to “Wheel Motors Tests” on
page 5-43.
Wheel Motors Tests
See Figures 5-38 through 5-45.
IMPORTANT
• Performing this test will isolate the wheel motors
from the rest of the hydrostatic system.
• This test works together with the traction system
test, traction pump tests, and flushing valve
check valve test to isolate a problem within the
hydrostatic power train.
!
WARNING
NOTE
Procedure is for 3WD models. Procedure for 2WD
models is the same except where noted.
1. Park the mower safely. (See “Park Mower Safely” on
page 1-6.)
2. Before performing this test, perform traction pump
tests, leaving rear of mower lifted and supported
(3WD models), and flow meter and front wheel
restraints connected as outlined. (See “Traction
Pump Tests” on page 5-41.)
3. For 2WD models, remove blocking disks from
between tee fitting (1) and hose (2), and between tee
fitting (4) and hose (3) as identified in traction pump
tests. (See “Traction Pump Tests” on page 5-41.)
4. For 3WD models, remove blocking disks from
locations (6 and 8) as identified in traction pump
tests. (See “Traction Pump Tests” on page 5-41.)
5. Connect hoses back to flow meter as outlined in
traction system test. (See “Traction System Test” on
page 5-37.)
11
TN3947
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
• -8 ORFS Test Hoses 4000 psi (276 bar)
• -8 ORFS Blocking Disk
• -10 ORFS Blocking Disk
• Flow Lock Tool
• Wheel Restraints