Central Air Drain Cocks (Optional) - Wittke STARLIGHT Maintenance Manual

72 Pneumatic System
Air Actuator Maintenance and Replacement
The air actuators on the main body valve shift the spools of the valve to operate the various functions
of the valve. The air actuators have two ports in a cylinder case located on either side of a piston,
which is attached to the valve spool. As air is supplied to a port, it pushes the piston, which in turn
shifts the valve spool to operate the function. A centering spring returns the valve to neutral when the
air pressure is lost.
The air actuators on the valve assembly look very similar to each other; all actuators are the same
except the actuator on the tailgate raise/lower section. The tailgate air actuator limits the stroke of the
valve spool due to the hydraulic needs of the tailgate circuit and the power-bleed circuit.
When troubleshooting an actuator that is not operating correctly, refer to the following tips:
 Verify the air actuator is receiving the proper air pressure. To do this:
• Install a 0-150 PSI air gauge in-line with the pressurized line.
• The gauge should read a minimum of 90 PSI.
 Verify the opposite port of the air actuator is not plugged. To do this:
• Remove the air line from the air actuator and operate.
 Verify that the air pressure inside the air actuator is not bypassing internally by following these
simple steps:
• Remove both air lines from the air actuator.
• Apply shop air to one side of the air actuator while feeling/listening for air exhausting from the
opposite port of the air actuator. Repeat in both directions.
• If air is bypassing, service or replacement of the air actuator is necessary.
 Ensure the inside of the air actuator is free from debris and damage. Clean with a lint-free rag and
lightly lubricate with Parker's Super-O-Lube or a silicon-based equivalent.
LabriePlus offers a seal kit to replace the internal seals in the actuator. Contact LabriePlus for more
details.

Central Air Drain Cocks (optional)

A series of air drain cocks may be provided on a bracket below the battery box.
Figure 6-11 Central air drain cocks