4 — MAINTENANCE
Pressure Relief Valve Adjustment
Perform the following procedure to adjust the pressure relief valve. Refer to Figure 4-6.
1. Move the ESP 19 lift platform to the fully
DOWN position.
2. Center 450 pounds of weight on the lift platform.
3. Loosen the jam nut. The pressure relief valve is on the back side of the pump.
4. Turn the pressure relief valve adjust screw 1/8
th
turn counterclockwise. This
will adjust the relief valve bypass pressure setting for less than 450 pounds of
lift.
5. Place the key switch in the
LOWER CONTROL position and press the UP pushbut-
ton. The pump should run, bypassing oil to the hydraulic reservoir.
CAUTION
Do not adjust the pressure relief valve for a bypass pressure higher than needed
to raise the 450 pound load. Hydraulic system overload may occur at a higher
bypass pressure, causing hydraulic failures or damage to the equipment.
6. With the platform lift function enabled (pump running), turn the pressure relief
valve adjust screw clockwise just enough to smoothly raise the platform with-
out bypassing oil to the hydraulic reservoir.
7. Retighten the jam nut.
Figure 4-6. Pressure Relief Valve Adjustment
4-7
