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Reelmaster 3550−D Hydraulic SystemPage 4 − 53
Cutting Unit Circuit Testing − Gear Pump (P1) Flow
Test:
The gear pump (P1) flow test is the last in a series of
tests recommended to determine cutting unit circuit per-
formance. This test compares fluid flow at No Load with
fluid flow Under Load. A drop in flow under load of more
than 15% indicates the gears and wear plates in the
pump have worn. A worn pump will by−pass hydraulic
fluid and make the pump less efficient. Eventually,
enough fluid loss will occur to cause the cutting unit mo-
tors to stall under heavy cutting conditions. Continued
operation with a worn, inefficient pump can generate ex-
cessive heat and cause damage to the seals and other
components in the hydraulic system.
Special Equipment Required:
S Flow Meter with Pressure Gauge that has at least
a 12 GPM (45 LPM) capacity.
S Phototach (non−contact tachometer).
1. Park machine on a level surface with the cutting units
lowered and reel enable/disable switch in the disengage
position. Make sure engine is off and the parking brake
is engaged.
2. Read Precautions for Hydraulic Testing in this
chapter.
3. Disconnect hose connection on the gear pump (P1)
leading to port (P) on the mow control manifold (Fig. 36).
4. Install tester between the gear pump and the discon-
nected hose.
5. Make sure the flow control valve on the tester is fully
open.
6. Sit in the operator’s seat and start the engine. Move
the throttle to full speed (3220 +
50 RPM).
7. Make sure hydraulic fluid is at normal operating tem-
perature by operating the machine for approximately 10
minutes.
8. Verify with a phototach that the pump speed is ap-
proximately 3090 RPM.
9. Verify pump flow at No Load as follows:
Record tester pressure and flow reading at no load.
Unrestricted pump output should be approximately
7.3 GPM (29.3 LPM).
1
. Gear pump assembly
2
. To mow control manifold
(P) port
Figure 36
1
2
FRONT
RIGHT
P1
P2
10.Verify pump flow Under Load as follows:
CAUTION
Do not close tester valve fully when perform-
ing this test. In this test, the hydraulic tester is
positioned before the manifold relief valve.
Pump damage can occur if the fluid flow is fully
restricted by fully closing the tester flow con-
trol valve.
A. Watch flow meter pressure gauge carefully while
slowly closing the flow control valve until 2000 PSI
(137.9 Bar) is obtained on gauge.
B. Record tester pressure and flow readings under
load.
11.Set throttle to low speed and shut off engine.
12.The under load test flow reading (step 10.B) should
not drop more than 15% when compared to no load test
flow reading (step 9.A). A difference in flow of more than
15%, or the inability to achieve specified pressure may
indicate:
A. A restriction in the pump intake line
B. A Worn and/or slipping traction belt
C. The gear pump (P1) is worn and should be re-
paired or replaced
13.Disconnect tester and reconnect hose to pump.
Hydraulic
System