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Greensmaster 3320/3420 Hydraulic SystemPage 5 -- 31
10.If specification is not met, remove piston pump back
plateassembly that containsthe charge relief valve (see
Piston (Traction) Pump Service in the Service and Re-
pairs section of this chapter). Repair or replace relief
valve components as necessary.
11.Adynamic chargepressuretest canbe performedas
follows:
A. Position machine so that a load can be placed on
the tractionsystem. For example, chain the machine
to an immovable object or chock all drive wheels to
prevent the machine from moving.
B. With pressure gauge still connected, sit in the op-
erator seat, start the engine and move throttle so en-
gine is running at high idle speed. Move functional
control lever to the transport position.
C. While monitoring the pressure gauge, push the
traction pedal in the appropriate direction (forward or
reverse) to allow traction system load.
D. Once dynamic charge pressure has been deter-
mined, move throttle to low idle speed and shut off
engine. Record test results.
E. The charge pressure should drop no more than
20% from no--load charge pressure measured in
step 9 above (e.g. if charge pressure in step 9 is 125
PSI (8.6 bar), charge pressure in forward or reverse
should be more than 100 PSI (6.9 bar).
F. If charge pressure is good under no load, but
drops below specification when under traction load,
the piston (traction) pump and/or wheel motors
should be suspected of wear and inefficiency. When
the pump and/or traction motor(s) are worn or dam-
aged, the charge pump is not able tokeep up with in-
ternalleakageintractioncircuit components.Further
testing of the traction circuit should be completed
(see Piston (Traction) Pump Flow and Wheel Motor
Efficiency Tests in this section).
12.When charge pressure testing is complete, discon-
nect pressure gauge and tee fitting from the hydraulic
hose and hydraulic tube. Connect hose to tube.
1. Gear pump
2. Hydraulic hose
3. Hydraulic tube
4. Piston (traction) pump
Figure 21
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Hydraulic
System