SFN-20240104A Swap supply and exhaust air lines

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TICO Document #: SFN-20240104A (Formerly TES 187)

Description of Procedure: The solenoid valve controlling the dolly master’s lift cylinder is plumbed as normally closed, supplying air to the lift cylinder when the switch is pressed. This is preventing the dolly master from falling. Swap the supply and exhaust air lines on the solenoid valve, converting the valve from normally closed to normally open.

Units Affected: N/A

Parts Required: N/A

Planned Labor: 30 minutes

Inspection:

• Sitting in the driver seat of the cab, press and hold the dolly master switch. The dolly master should fall and remain down as long as you are holding the switch. Once released, the dolly master should be raised to its original position.

• If the dolly master does not function as stated above, then proceed with the solution.

Instructions:

  1. Park the vehicle on a flat surface, apply a parking brake, and chock wheels. If your company utilizes a “Lock Out, Tag Out” policy, you should employ it during this procedure.

  2. Remove the solenoid valve mounting plate located under the cab floor on the left-hand side.

  1. Locate the solenoid valve with the 3/8” black airline in the delivery port (2). This valve controls the dolly master’s lift cylinder.

  1. On this valve, swap the airlines in ports 1 & 3. Port 1 should now be plumbed to the atmosphere (Exhaust), and port three should be plumbed to the manifold (Supply).

  1. Reinstall the solenoid valve mounting plate to the bottom of the cab floor.

  1. Remove “Lock Out, Tag Out” plaque.

  1. Return vehicle to service.