PIPE ASSEM. 7L7852 - Caterpillar

Introduction
The idler pump and the drive pump receive signal oil pressure from the center bypass passages of the main control valve. This signal oil pressure that is created in the center bypass passages of the main control valve is called negative flow control pressure. Negative flow control pressure flows to the regulators at the idler pump and the drive pump in order to control the output flow of the pumps. Negative flow control pressure is created during the following machine operating conditions.
All of the joysticks and travel levers/pedals are in the NEUTRAL position.
Any of the joysticks and/or travel levers/pedals are partially moved from the NEUTRAL position in order to perform a fine control operation.
Illustration 1 g00819938
Main Control Valve (Top View) (12) Negative flow control line to drive pump (13) Negative flow control line to idler pumpThe right body of the control valve receives supply oil from the idler pump. Negative flow control pressure from the right body of the main control valve flows through negative flow control line (13) to the idler pump. The left body of the control valve receives supply oil from the drive pump. Negative flow control pressure from the left body of the main control valve flows through negative flow control line (12) to the drive pump. The negative flow control operation