PAD-STABILIZER 9R7893 - Caterpillar

D11N Tractors;
777B, 785 Trucks;
3500 Family Of EnginesReference: Caterpillar 3161 Service Manual, SENR3028. Add a Note to this publication on Page 43 referring to this article. The Service Manual states that the cocking pressure (or arming pressure) for the fuel ratio control has to be set on a test bench. This is no longer necessary. The following procedure makes it possible to adjust the arming pressure on the engine in any application. If the fuel ratio control diaphragm or the control itself is replaced, the control arming pressure, as well as the fuel limit level for the fuel ratio control should be adjusted. The 3161 Service Manual already covers the fuel limit adjustment on Page 43. However, when the following procedure is used to adjust the arming pressure, the fuel limit level is also adjusted at the same time.
1. From the Fuel Setting And Related Information Microfiche or the engine information plate, write the figure for the dynamic fuel ratio control setting. Also, the arming pressures for the fuel ratio controls are: ... 777B, 785 Trucks: 26.9 to 41.0 kPa (3.9 to 5.9 psi)
... 3500 Family Marine: 5 to 12 kPa (.7 to 1.7 psi)
... 3500 Family Industrial, Generator Sets: 10.3 to 24.1 kPa (1.5 to 3.5 psi)
These arming pressures will be in a future issue of the microfiche.
2. Install and zero in the dial indicator on the side of the engine front drive housing for checking fuel setting. See Illustration 1. See FUEL SETTING in the Testing and Adjusting Section of the Engine Service Manual for the procedure to use.3. Disconnect boost line from the fuel ratio control. Plug the boost line to keep dirt and foreign material out of the engine.4. Connect an outside air supply with a pressure regulator and gauge assembly to the fuel ratio control. See Illustration 1.
Illustration 1. Setup for using outside source of air pressure.
Work carefully around an engine that is running. Engine parts that are hot, or parts that are moving, can cause personal injury.
5. Start the engine and apply an air pressure of 70 kPa (10 psi) to arm (activate) the fuel ratio control. Now, lower the air pressure to the specified arming pressure.6. Remove the plug from the right front corner of the top cover. See Illustration 2. Put a 3/16" hexagonal wrench through the hole in the top cover until it engages the fuel limit adjustment screw. Turn the adjustment screw clockwise until engine speed starts to drop. The engine should stop. Count and record the number of turns required for adjustment so you can use this same setting later in this procedure.
Illustration 2. Location of screw for fuel limit adjustment.7. Shut off engine if it did not stop in previous Step. Remove the aluminum plug from top of fuel ratio control. Use a pair of locking pliers to grip and turn out this plug.8. Use a 1/8" hexagonal wrench to turn the arming adjustment screw two turns clockwise. See Illustration 3.
Illustration 3. Location of arming adjustment screw.9.