SCREW 1B1291 - Caterpillar

( 22X459-Up, 23X786-Up, 26X884-Up ),
D6D ( 5X841-Up, 3X993-Up ),
D7G ( 91V1710-Up, 35N1-Up ),
D8K ( 76V812-Up ) Tractors With Direct Drive TransmissionsSome of the above tractors have been found on which the neutral start switch did not operate correctly. The purpose of this switch is to prevent operation of the starting motor when the flywheel clutch is engaged. Correct operation of the switch is very important for two reasons. The first and most important reason is safety, since it prevents possible movement of the machine when the engine is started. The second reason is easier starting, with less load on the starting and electrical systems, especially in cold temperatures.
The neutral start switch can be easily checked for correct operation, and the recommendation is to do this any time service work is done on the machine. To check the switch for correct operation, use this procedure.
1. Put the transmission control in neutral, and engage the parking brake.2. Move the flywheel clutch control lever to the clutch engaged position, and turn the heat-start switch to the start position. The starting motor must not activate.3. Move the flywheel clutch control lever to the clutch disengaged (clutch released) position, and again turn the heat-start switch to the start position. The starting motor must now activate.If, as a result of this test, there is any indication that the switch does not operate correctly, make sure the flywheel clutch control linkage is correctly adjusted before any other changes are made. Information for adjustment of the clutch linkage is given in the Specifications section of the Service Manual.
When the clutch control linkage is correctly adjusted, there are two possible problems with the neutral start switch: Either the engine will start, or will not start, with the clutch control lever in both the clutch engaged and clutch disengaged positions.
If the engine will not start, and there is no failure in the electrical circuit, the probable cause is a bent or damaged part. Check to see that the flat surface on the clutch control shaft moves the switch plunger a minimum distance of 1.14 mm (.045") when the clutch control lever is moved to the clutch disengaged position. If the switch plunger does not move this minimum distance, make necessary repairs.
If the engine starts with the clutch control lever in either position, the switch body is probably too near the clutch control shaft, so the shaft holds the switch plunger in. When the clutch control lever is in the clutch engaged position, the flat surface on the clutch control shaft can be in contact with the switch plunger, but the plunger must be held in less than 0.38 mm (.015"). When the switch plunger moves in a distance of 0.38 to 1.14 mm (.015 to .045"), the switch contacts close.
The problem of the switch plunger held in so the contacts are closed, has been caused on some machines by damage to the switch mounting bracket when the nut was tightened too tightly on the switch body. The correct