BODY AS-EXHAUST COMBUSTION 3818112 - Caterpillar

The neutral adjustment is the only adjustment that can be made on the electrical displacement control for the 90 series pumps. Adjusting a neutral adjusting screw (1), which is located on the end of the EDC control, performs the neutral adjustment. Locate the two displacement control cylinder gauge ports M4 (1) and M5 (2) on top of the pumps.
1. Install two 124-8909 90 Degree Elbows and two 7X-5315 Pressure Test Fittings into M4 (1) and M5 (2) gauge ports.2. Install two 8T-0855 Pressure Gauges (0-580 psi) on test fittings. Under normal working conditions, this pressure could be as high as charge pressure. The pressure will be different on each pump. This is because of the different routing of the case drain lines. The left hand pump case drain runs through the case drain filter and oil cooler. The right hand pump case drain line runs to the front return manifold.3. Disconnect the EDC electrical connection at the pump.4. On the AP-1000B/BG-260C the balance lines between both pumps will have to be plugged and capped using two 6V-9507 Plugs, two 6V-9828 Caps and two 4J-5477 O-rings. Caution should be taken not to bring the pressure too high or the gauges could be damaged.5. Start the engine and run at high idle until the hydraulic oil temperature is 38°C (100°F) or higher. Read the pressure gauges. If the pressure is below kPa (140 psi), remove the gauges and replace them with 8T-0854 Gauges (0-145 psi). (Caution: IF THE PUMP IS STROKED MANUALLY DURING THE TEST, THE GAUGES WILL BE DAMAGED). The pressure reading on the gauges should be equal, if not adjust the EDC adjustment screw on the end of the controller with the following steps: A) Using a 13 mm wrench and a 4 mm Allen wrench for the neutral adjustment screw, rotate clockwise until the pressure increases on one of the gauges. Note the angle of the wrench and the pressure reading of the gauge. Caution should be taken not to bring pressure too high otherwise the gauges could be damaged.B) Rotate the adjusting screw counterclockwise until the pressure increases by the same amount that was read on the other gauge. Note the angle of the Allen wrench and the pressure reading of the gauge.C) Rotate the adjusting screw clockwise half the distance between the noted positions from the above steps. The gauges should now read the same pressure kPa ( 5 psi), this indicates the control is in the neutral position. If not, repeat step 5.6. Remove the gauges and fittings, reinstall the port plugs and reconnect the EDC.7. Follow steps 1 through 6 on the opposite pump.8. For the AP-1000B/BG-260C, reconnect the balance lines between both pumps.9. After the pumps have been nulled, recalibrate the MPC-10 initial pump currents using KENR2949.