COUPLER 4994702 - Caterpillar

Introduction
This Special Instruction provides the information that is necessary to inspect the overspeed protection and air shut-off.The customer supplied actuator must allow 74 degrees of rotation and apply a torque of 5 1 N m (44 9 lb in) to the air shut-off shaft.Excessive torque may damage air shut-off components and insufficient torque may not close the butterfly plates completely.Overspeed Protection
To ensure that the overspeed protection is functional, perform the following overspeed procedure when initially packaged and at each oil change.
Confirm secure wiring connections between the ECM, air shut-off relay, air shut-off solenoid, and battery.
Carry out a 75 percent overspeed. Verify procedure by grounding the appropriate pin and commanding a desired speed beyond this point.Note: There will be an overspeed warning before the actual overspeed shutdown.See the applicable Electronic Application and Installation Guide for specific details on wiring an overspeed verify switch.
Ensure air shut-off was actuated (do not assume because engine shutdown, that the air shut-off is closed).Note: Ensure that the air shut-off is reset when completed.Air Shut-off Seal
Caterpillar recommends that a visual inspection is performed to ensure that the butterfly plates are closing, and that the customer supplied actuator is operating as designed.