Smart Power Systems
®
A. C. MODULAR GENERATOR SYSTEM
Page 43 of 52
3.
Differential Pressure:
Differential pressure between the inlet pressure and the case pressure over 7
psig causes the piston shoes to lift off the swash plate.
This occurs due to the
excessive lower pressure created on the fill (down) stroke of the piston. When the
swash plate begins its upstroke, with pump rotation, it comes back into contact with
the piston shoe, creating chatter.
NOTE: This is NOT NORMAL
. The piston shoes should always remain in contact
with the swash plate. The causes of and correction for this problem are the same
as for cavitation above.
With the pressure gauge still installed in the suction line at the pump inlet port,
install a second gauge (0-50 psig pressure gauge) in the case drain line at the
pump case port. Next, engage the PTO and operate the genset with no load for
twenty minutes to purge air out of the fluid. Note both gauge readings. If the
differential pressure at the case is greater than 7 psig, the suction side plumbing will
require evaluation.
Note the following pressure measurements!
Inlet pressures:
Should always be positive.
Outlet pressure:
Approximately 500 psig with no load on the generator.
Note:
If
the gauge is fluctuating, record limits.
Case drain pressure to inlet pressure differential:
The difference between
pump inlet pressure and case drain pressure should not exceed 7 psig. Pump inlet
pressure minus case drain pressure should never be less than 7 psig.
Verify the installation of the following hydraulic generator hose diameters:
a.
Inlet hose (suction) on hydraulic pump (attaches to Port “S” on back of pump): 1
inch
b.
Outlet hose (pressure) on hydraulic pump (attaches to Port “B” on back of
pump): 1/2 inch
c.
Case drain to hydraulic pump (attaches to Port “L” top side, mid-length of pump):
5/8 inch
Note:
The hose diameter appears in print along the length of the hose.
