Textron Jacobsen SLF530, Repair Manual

Page: 151 / 352

HYDROSTATIC POWER TRAIN
673831-Rev A 5-25
5
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
decide 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: Traction System Performance Complaint
The machine operator reports the machine struggles to
climb hills.
A charge pressure test must first be performed to rule out
a charge pump issue. Next, the traction system is tested
as outlined, and the calculated system leakage is 43%, a
result which requires the testing of individual
components. This result can also be interpreted as the
system is 57% efficient.
The remaining components in question are the traction
pump and the wheel motors. Following the procedures as
outlined, test each individual component, then calculate
and record leakage percentages.
The results from this test reveal leakage of 6.7% in the
traction pump, 3.7% in the left front wheel motor, 5.2% in
the right front wheel motor and 32.9% in the rear wheel
motor. Although all of the components lend to the overall
system leakage, only the rear wheel motor, which is in
the bad range, would be considered for
repair/replacement.
Formulas:
System and Traction Pump
No Load Flow – Loaded Flow / No Load Flow x 100 =
Leak Percentage
Front Wheel Motors, Rear Wheel Motor(s) and 4WD
Valve (4WD Option)
Loaded Flow from previous component – Loaded Flow
from current component / Loaded Flow from previous
component x 100 = Leak Percentage
Charge Pressure Test
See Figure 5-15.

WARNING
1. Operate hydraulic system until oil temperature is at
120–150° F (49–65° C).
2. Park the mower safely. (See “Park Mower Safely” on
page 1-6.)
Figure 5-15
3. Remove plug (1) and assemble fitting (2) to “G” test
port on rear reel valve (3).
4. Connect hose and pressure gauge (4) to fitting (2).
5. Put the parking brake switch in the ON position.
NOTE
Verify engine rpm is within specification (3000 rpm ± 50)
to ensure accurate hydraulic test results.
6. Start engine and run at full throttle (3000 rpm ± 50).
7. Record pressure reading.
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
• Pressure Gauge 500 psi (35 bar)
• Test Hose 500 psi (35 bar)
• -6 ORB Fitting
MAR00 8 0
250
psi
BAR
0
5
10
15
20
2
5
30
35
300
350
4
0
0
450
500
200
150
1
0
0
5
0
0
1
2
3
4