ENGINE AR-PRIMARY 3903702 - Caterpillar

Two-Way Flow from Two Pumps
Illustration 7 g01538633
Illustration 8 g01538634Description
The default parameter values for two-way hydraulic oil flow from two main pumps are shown in Table 1. A typical example is a pulverizer. Refer to Testing and Adjusting, "System 14: Default Value of Work Tool Parameters" for the Tool Control System.The work tool is operated by right joystick slide control (36).Note: Refer to Testing and Adjusting, "System 14: Default Value of Work Tool Parameters" and Testing and Adjusting, "Work Tool Parameter - Program" for the Tool Control System.Operation
Pilot pump (31) supplies oil to pilot manifold (26). When the hydraulic activation lever is moved to the UNLOCK position, pilot oil flows from pilot manifold (26) to the solenoid valves: (5), (6), (14), (15), (16) and (17).When right joystick thumbwheel (36) is moved FORWARD, the machine ECM sends a signal to the extend solenoid for attachment control valve (16) and the extend solenoid for auxiliary control valve (14). The signal is proportional to the forward displacement of the joystick thumbwheel. The machine ECM also sends a signal to the solenoid for number one check valve "EC1" (11) in order to open the valve. Pilot oil flows to the top of attachment control valve (21) and auxiliary control valve (20). The pilot oil will shift the spool in each control valve DOWNWARD. This allows oil from drive pump (30) to flow through attachment control valve (21) and this also allows oil from idler pump (29) to flow through auxiliary control valve (20). The hydraulic oil from the two pumps combines after the oil passes through both valves. The pump oil flows through the line for the work tool (9) to the work tool. The working pressure for the work tool is limited by the line relief valve for the work tool (12) through number one check valve "EC1" (13).When right joystick thumbwheel (36) is moved BACKWARD, the machine ECM sends a signal to the retract solenoid for attachment control valve (17) and the retract solenoid for auxiliary control valve (15). The machine ECM also sends a signal to number two check valve "EC2" (11) in order to open the valve. Pilot oil flows to the bottom of attachment control valve (21) and auxiliary control valve (20). The pilot oil will shift the spool in each control valve UPWARD. This allows oil from drive pump (30) to flow through attachment control valve (21) and this also allows oil from idler pump (29) to flow through auxiliary control valve (20). The hydraulic oil from the two pumps combines after the oil passes through both valves. The pump oil flows through the line for the work tool (8) to the work tool. The working pressure for the work tool is limited by the line relief valve for the work tool (10) through the number two check valve "EC2" (11).During operation of the work tool, the machine ECM sends a signal to the proportional solenoid valve for negative flow control (18). Negative flow control pressure in the center