Hydraulic Valve Pressure Adjustment; Hydraulic Valve - Gravely Promaster 300 Service Manual

8.7 HYDRAULIC VALVE PRESSURE
ADJUSTMENT
Pressure check for valve
1. Remove the hose fitting at the valve outlet (high
pressure line to cylinder) and install a pressure
gauge. Use two wrenches to avoid breaking the
fittings.
2. Start the engine and run at full throttle. Move the lift
control lever to the "UP" position and hold. The
pressure should read a maximum of 900 psi.
NOTE: If the pressure reading is too high or low it can
be adjusted with the relief valve in the hydraulic control
valve assemble.
3. Remove the acorn nut on the valve body. Loosen
the jam nut while holding the adjusting screw with a
screwdriver.
4. Start the engine and run at full throttle. Have
another person hold the hydraulic lift control in the
"UP" position while observing the pressure gauge.
Rotate the adjusting screw clockwise to increase
the pressure. Rotate the adjusting screw
counterclockwise to reduce the pressure. Take
care not to move the adjusting screw when
tightening the jam nut.
5. Reverse the disassembly procedure to
reassemble.

8.8 HYDRAULIC VALVE

1. Remove the top four screws holding the front
silkscreen panel in place and loosen the bottom
two. Flip the panel open to expose the valve and lift
lever components.
2. Disconnect the two high pressure hoses and the
low pressure two-way fitting. It is not necessary to
disconnect the low pressure hoses from fitting.
3. Remove the cotter key holding the two hydraulic
control rods to the hydraulic valve.
4. Remove the four bolts mounting the valve to the
panel.
5. Inspect and replace any parts as needed.
6. Reverse the disassembly procedure to
reassemble.
NOTE: On the earlier models of the Promaster 300, the
lift position was "forward", hold position "center" and
float position "back". These current models are
reversed. Float position is "forward", hold position "cen-
ter" and lift position "back".
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