HEAD 1895629 - Caterpillar

All 3600 Diesel EnginesIntroduction
To reduce dealer inventory, common service replacement pressure contactors have replaced the original equipment pressure contactors. The service replacement pressure contactors are preset to a standard setting. This setting must be calibrated to the correct pressure range for its application. The 7C-5954, 121-0242, and 121-0243 Pressure Contactors are factory preset; no calibration is required before installation.This Special Instruction includes the procedure to test and calibrate the pressure range of the contactor to specific actuation and deactuation pressure settings.It is also recommended that each contactor be checked for correct calibration and recalibrated using the calibration procedure for the pressure contactor model to be replaced. Refer to Chart A for a listing of all pressure contactors used on 3600 Diesel Engines and the specified replacement contactor part numbers and their corresponding model numbers. When ordering a replacement pressure contactor, be sure to order the part number of the service replacement pressure contactor listed in Chart A and not the part number of the pressure contactor being replaced. This ensures receiving the correct service replacement part.Do not perform any procedure, outlined in this publication, or order any parts until you have read and understood the information contained within this Special Instruction.Reference: Refer to Special Instructions SEHS7734, "Use of 6V-7070 Heavy-Duty Digital Multimeter and 6V-7800 Regular-Duty Digital Multimeter" for instructions on the use of this multimeter. Required Equipment
The following is a list of equipment required to test and calibrate pressure contactors.* 6V-7070 Multimeter or Equivalent A multimeter is used to verify the actuation and deactuation settings. This is done by checking for continuity between two terminals inside the contactor.* Air Compressor and Pressure Regulator An air source is used to supply the air pressure to the contactor. Make sure the maximum obtainable air supply is slightly greater than the pressure required to set the actuation pressure setting. The pressure regulator allows the pressure to be gradually increased or decreased to the specified pressure.Calibration Procedure for Model KPS 35 and KPS 37 Contactors
Use the following procedure to check and calibrate pressure contactor models KPS 35 and KPS 37.1. If connected, disconnect the contactor from the power supply. Mark terminal locations and disconnect the three wires from terminals 1, 2, and 4.
High voltage electrical shock is possible. The contactor must be disconnected from the power supply and the wires disconnected from terminals 1, 2, and 4. Failure to follow this recommendation can result in serious bodily injury.
2. Locate and record the part number of the pressure contactor in Chart A. Using the part number and Chart A, determine the actuation and deactuation pressures. Verify that the contactor being tested is a model KPS 35 or KPS 37. If not, refer to the procedure for the specific model of pressure contactor being tested.
Pressure Contactor
(1) Housing cover. (2) Housing cover screws. (3) Pressure port.3. Loosen housing cover screws (2) as shown and remove housing cover (1).4. Connect the air supply to the pressure port (3). The air pressure regulator should be set to