HYDROSTATIC POWER TRAIN
673831-Rev A 5-27
5
Verify engine rpm is within specification (3000 rpm ± 50)
to ensure accurate hydraulic test results.
8. Start engine and run at full throttle (3000 rpm ± 50).
9. Use the flow meter to warm the hydraulic oil. Turn the
flow meter valve (5) until a reading of 1100 psi (76
bar) or one half of the relief valve rating is reached.
Warm oil to 120–150° F (49–65° C).
10. Open flow meter valve (4) completely. Read and
record the charge pump no load flow.
11. Slowly close flow meter valve (5) until pressure
reaches 1600 psi (114 bar). Read and record the
charge pump loaded flow.
12. Open flow meter valve (4) and stop engine.
13. Calculate charge pump leakage.
(Step 10 – Step 11 / Step 10 x 100 = Leak
Percentage)
Is charge pump leakage 10% or less?
YES The charge pump is good. Proceed to
step 14.
NO Proceed to next question.
Is charge pump leakage 11% to 20%?
YES The charge pump is marginal. Additional
testing is required. (See “Field Test
Procedures” on page 6-23.)
NO Proceed to next question.
Is charge pump leakage 21% or more?
YES Repair or replace charge pump. (See “Gear
Pump” on page 6-49.)
14. Disconnect and remove test equipment. Install all
hoses and fittings as noted prior to removal.
15. Install and connect all components as noted prior to
test.
16. Check hydraulic oil level. Add oil as needed. (Refer to
“Safety, Operation, and Maintenance Manual” for
correct oil specifications.)
Flow Lock Tool
See Figures 5-19 and 5-20.
• Dimensions shown are approximate. Adjustment
may be required for the mower.
Figure 5-19
Figure 5-20
1. A flow lock tool (1) is required to test the hydrostatic
system. Obtain or make a flow lock tool that can be
adjusted to the dimensions shown.
2. Disconnect traction pedal cable hardware (2) from
the pump arm. If necessary, move traction cable to
prevent interference with traction pump arm
movement.
3. Remove traction arm damper (3).
4. Install flow lock tool (1) to hydraulic pump using
damper mounting hardware.
5. Adjust the flow lock tool by loosening jam nuts (4)
and adjust turnbuckle (5) until the proper flow is
obtained. Tighten the jam nuts to set the adjustment
Do not exceed 2200 psi (152 bar) as this test does
not utilize system relief.
210 mm (Full Reverse)
223 mm (Neutral)
237 mm (Full Forward)
M8-1.25 RH Thread
M8-1.25 LH/RH Turnbuckle
M8-1.25 RH Thread
M8-1.25 LH Thread
Jam Nuts
1
2
3
5
4
4
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