TUBE AS 2939872 - Caterpillar

Do not turn the speed control knob unless the test bench is running. Damage to the variable speed drive may result. Except in the event of an emergency, the speed control knob should always be returned to the slowest rpm setting before the calibration bench is turned off.
Turn the control knob for the governor speed counterclockwise to the slowest speed. Inspect all of the fluid connections for leakage. Perform any necessary repairs.Note: Always approach a specified rpm setting from a minimum of 100 rpm above the rpm that is required. This will ensure that the test readings are consistent for the entire test procedure.All specifications for the governor adjustment procedure are in the Technical Marketing Information (TMI). If you are checking a previously adjusted governor, the tolerance ( ) factor should be doubled. The tolerance factor should be referred to as an expanded tolerance.As an example, if a tolerance in the specifications is listed as 0.05 mm ( 0.0020 inch), then the expanded tolerance for this checking procedure would be increased to 0.10 mm ( 0.0039 inch). This expanded tolerance will not be listed in the specifications. The tolerance must be calculated by the operator of the governor calibration bench.
Illustration 1 g00657715
(1) Fuel ratio control (2) Throttle stop adjustment screw
If the governor is equipped with a fuel ratio control (FRC), connect a regulated air supply (a hand pump or a squeeze pump) to the fuel ratio control.
A regulated air supply of 140 to 210 kPa (20 to 30 psi) must be used to avoid damage to the fuel ratio control.
Adjust the