COVER 4416011 - Caterpillar

TECHNICAL INFORMATION BULLETIN March 12th, 2003
Wheeled Excavators M316C (BDX)
M318C (BCZ)
M322C (BDK)
Component Code(s) 1915SUBJECT: AUTOMATIC ENGINE CONTROL REGULATES ERRATICALLY ON M300C-SERIES WHEELED EXCAVATORS
PROBLEM:
The setting of the minimum swash plate angle Qmin on the main pump is too low, causing the pump to regulate incorrectly. This in turn causes the AEC to engage and disengage erratically.
SOLUTION:
Perform the following procedure only when the machine is running and the hydraulic oil temperature is 55oC ? 5oC. Also, place the engine speed dial into Position 1.
Attach an 8T-0854 pressure gauge (maximum pressure 6000kPa / 870PSI) to the pressure tap for the main pump (Pos 1, Figure 1).
Illustration 1. Item 1 indicates the location of the main pump pressure tap
Remove the cap from the Qmin adjustment screw, located on the bottom of the main pump.
Illustration 2. Location of the Qmin adjustment screw
Adjust the Qmin setting by turning the screw clockwise, and increase the pressure of the main pump to 3500kPa / 508PSI at idle (no load) and engine speed position 1.
Warning: Before operating the machine remove the pressure gauge from the pressure tap.
Upon completion, use Caterpillar Electronic Technician (ET) to adjust the operating threshold of the swash plate angle sensor to +0.8? above the current swash plate angle value.
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