SUPPORT AS 4285841 - Caterpillar

The 9U-7400 Multitach can measure engine speed from a tachometer drive on the engine. The multitach also has the ability to measure engine speed from visual engine parts in rotation.Refer to Special Instruction, SEHS7807 for instructions about the test procedure.The 6V-4950 Speed Pickup is another diagnostic tool accessory that can be used with the 9U-7400 Multitach. The speed pickup can be used on all Caterpillar Diesel Engines that are equipped with 6 mm (0.25 inch) single wall fuel injection lines. Engine speed can be measured quickly and automatically with this pickup group. The accuracy is 1 rpm.
Illustration 17 g01247197
6V-4950 Speed Pickup (1) 6V-6113 Pickup Amplifier (2) 6V-6114 Pickup Refer to Special Instruction, SEHS8029 for instructions on using the 6V-4950 Speed Pickup .Check Set Point (Balance Point)
An engine relies on set point for the correct operation of the engine. The set point check of the engine is a method that will diagnosis engine performance.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 set point.
Table 7
Required Tools    
Part Number     Part Name     Quantity    
9U-7400     Multitach     1    
Illustration 18 g00300249
9U-7400 Multitach You can use the 9U-7400 Multitach to check the set point. Refer to Special Instruction, SEHS7931 for instructions on using this tool group.Alternate Method for Checking Set Point
Table 8
Required Tools    
Part Number     Part Name     Quantity    
9U-7400     Multitach     1    
8T-0500     Continuity Tester     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 determined by these factors:
20 rpm greater than full load rpm.
The rpm upon contact between the rack stop collar and the torque spring or the stop bar.
The rpm where the engine gets the maximum amount of fuel per stroke.
The rpm where the engine has maximum horsepower output.
The rpm where an increase in load on the engine puts the engine in a lug condition. A lug condition is where a small increase in load causes the engine speed to decrease.Use the following procedure to check the set point.
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Circuit tester (installed) (1) Brass terminal screw (2) 8T-0500 Continuity Tester Note: Refer to Special Instruction, SEHS7050, "Techniques for Loading Engines" for more information.
Connect an accurate tachometer to the tachometer drive.
Connect the clip end of the 8T-0500 Continuity Tester to the brass terminal screw (1) 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