INSERT-THD 1285113 - Caterpillar

Refer to Illustration 36.An engine relies on the set point (balance point) for the correct operation of the engine. An engine's set point is an adjusted specification. High idle rpm is NOT an adjusted specification.The set point (balance point) equals full load rpm plus an additional 20 rpm. The set point is a measuring point that can be measured. At the set point, the fuel setting adjustment screw and the first torque spring just begin to make contact.At this rpm, the fuel setting adjustment screw and the first torque spring still have movement between the two components. When an additional load is put on the engine, the fuel setting screw with the stop, or the first torque spring will become stable. These components stabilize after the initial contact with pressure.Ultimately, the fuel setting adjustment screw and the first torque spring control the set point.There is a new, more accurate method for checking the set point of the engine. Review the required tools for the new method. If these tools are not available, you can use an alternative method for checking the set point.Note: See Special Instruction, NEHS0605 for instructions on the installation and usage of the Multitach Tool Gp .Alternative Method for Checking Set Point
Table 15
Required Tools    
Part Number     Part Name     Quantity    
8T-0500     Circuit Test Light     1    
9U-7400     Multitach Tool Gp     1    If the set point is correct and the high idle rpm is within specifications, the fuel system operation of the engine is correct.
The set point for the engine is 20 rpm greater than full load rpm.
The set point for the engine is at the rpm when the fuel setting screw first contacts the stop, or the first torque spring.Use the following procedure to check the set point:
Illustration 39 g00320609
Terminal Location (3) Brass terminal screwNote: See Special Instruction, SEHS7050 for additional information on loading an engine.
Connect an accurate tachometer to the tachometer drive.
Connect the clip end of the 8T-0500 Continuity Test Light to brass terminal screw (3) on the governor housing.
Then, connect the other end of the tester to a place on the fuel system with a good ground connection.
Personal injury can result from rotating and moving parts.Moving fan blades and moving parts will throw or cut any object or tool that falls or is pushed into them.Ensure that no one is working on, underneath or close to the machine before starting the engine. Ensure the area is free of personnel.
Start the engine.
With the engine at normal operating conditions, operate the engine at high idle.
Record the rpm of the engine at high idle.
Slowly add load to the engine until the circuit tester light just comes on. This is the set point.
Record the engine rpm at the set point.
To ensure that the correct reading is found, repeat Step 7 several times.
Stop the engine.
Compare the records from both Steps 6 and 8 with the information on the Engine Information Plate.If the Engine Information Plate is not