TM 5-3805-263-14&P-3
Start and run the engine at high idle rpm. Move the
control levers which operate the hydraulic cylinders to get
TESTING AND ADJUSTING
an increase in the temperature of the hydraulic oil.
When the temperature of the hydraulic oil is
approximately 30 F (17 C) more than the temperature
of the atmosphere, run the engine at high idle rpm. With
all of the control levers in HOLD position, look at the oil
pressure gauge.
The correct pressure is 2150 + 30 psi (151.1 + 2.1
kg/cm2). If the pressure of the pump oil is too low, the
pump or the combination valve or both the pump and the
combination valve need an adjustment or a repair.
CONTROL VALVE ON RIGHT SIDE
With the engine at high idle rpm, look at the oil
1. Plug (into passage for pump oil). 2. Plug. with two
pressure gauge and move each control lever separately.
7M1292 Adapter Assemblies and two 4M5317 Reducing
Hold the lever in position after the rod is either, in to, or
Bushings are used to make this test.
out of the cylinder as far as it will move. The correct
pressure is 3550+ 20 psi (249.6 + 1.4 kg/cm2) when a
A 1/4 in. hex wrench is used to remove plug (1) to
control lever is held both forward and to the rear. If the
the passage for pump oil and plug (2) for test of shuttle
pressure is too low, make a record of the pressure and
valve.
the position of the rod, either in, or out of the cylinder.
Start and run the engine at high idle rpm. Move the
Test each control. To test the circle drive control, stop
control levers which operate the hydraulic cylinders to get
the engine. Disconnect the two oil lines to the hydraulic
an increase in the temperature of the hydraulic oil.
motor at the control valve. Install metal caps on the
When the temperature of the hydraulic oil is
fittings in the control valve. The caps must keep the oil
approximately 300 F (170 C) more than the temperature
in the control when it is being tested. Start and run the
of the atmosphere, run the engine at high idle rpm. With
engine at high idle rpm. Look at the oil pressure gauge
all of the control levers in HOLD position, look at the oil
when the control lever is moved, both forward and to the
pressure gauges.
rear. If the oil pressure is too low, make a record of the
Hold the gauges close to each other so both can be
position of the control lever and the pressure. If the oil
checked at the same time. With the engine at high idle
pressure for both positions of each control lever is too
rpm, look at the oil pressure gauges and move the
low, the pump or the combination valve, or both the
control levers for blade lift. Hold the levers in raise
pump and the combination valve need an adjustment or
position after the blade lift cylinder rods are in as far as
a repair.
they will move. Both gauges should show 3550 + 20 psi
(249.6 + 1.4 kg/cm2).
If the oil pressure for both positions of only one
lever is correct and all of the other lever positions have
Return control levers to hold position. Gauge pressure
too low oil pressure, the check valve is open in the
on gauge connected to the opening for plug (2) will
control valve with the correct oil pressures. If the oil
slowly drop while the gauge pressure on gauge
pressure for one position of a control lever for one valve
connected to opening for plug (1) will stay at 3550 + 20
section is low and the other lever position has correct oil
psi (249.6 + 1.4 kg/cm2). When the gauge at (2)
pressure, there is damage in the resolver valve.
reaches 1500 + 50 psi (105.4 + 3.5 kg/cm2), the
SHIFT PRESSURE TEST FOR
pressure on the gauge at (1) will make a sudden drop to
SHUTTLE VALVE
2150 + 30psi(151.1 +2.1 kg/cm2). This is an indication
Two 7S8880 Oil Pressure Gauges [O to 5000 psi (O to
that the shuttle valve has shifted (moved) to cause the
352 kg/cm2)] two 5S4648 Hose Assemblies
pump to move from second stage to first stage. Oil
pressure for first stage is 2150 + 30 psi (151.1 + 2.1
kg/cm2) and second stage is 3550 + 20 psi (249.6 + 1.4
kg/cm2). If the shift pressure is not correct, add or
remove shims for shuttle valve as needed to cause the
pump to shift at the correct pressure.
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