Textron JACOBSEN R-311 69166, Technical/Repair Manual

Page: 196 / 402

HYDROSTATIC POWER TRAIN
4203781 First Edition 5-33
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 37%, a
result which requires the testing of individual
components. This result can also be interpreted as the
system is 63% efficient.
The remaining components in question are the traction
pump and the front axle motor. 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 and 32.9% in the front axle motor.
Although both the components lend to the overall system
leakage, only the front axle motor, which is in the bad
range, would be considered for repair/replacement.
Formulas:
Front Axle Motor, Rear Wheel Motors, Secondary
4WD Shuttle Valve, and 4WD Reverse Solenoid Valve
Loaded Flow from previous component – Loaded Flow
from current component / Loaded Flow from previous
component x 100 = Leak Percentage
System and Traction Pump
No Load Flow – Loaded Flow / No Load Flow x 100 =
Leak Percentage
Calculations:
System Test
No Load Flow = 15 gpm
Loaded Flow = 9.4 gpm
15 – 9.4 / 15 x 100 = Total System Leakage 37%
Traction Pump Test
No Load Flow = 15 gpm
Loaded Flow = 14 gpm
15 – 14 / 15 x 100 = Traction Pump Leakage 6.7%
Front Axle Motor Test
Loaded Flow from traction pump test = 14 gpm
Loaded Flow from front axle motor test = 9.4 gpm
14 – 9.4 / 14 x 100 = Front Axle Motor Leakage 32.9%
Charge Pressure Test
See Figures 5-20 and 5-21.
!
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.)
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)
• -8 ORFS Quick Coupler