NUT 1694809 - Caterpillar

Illustration 1 g02272916
Two-Way / One Pump - Electronic Control (1) Line (2) Line (3) Proportional reducing valve (A2 retract) (4) Proportional reducing valve (A1 retract) (5) Proportional reducing valve (A2 extend) (6) Proportional reducing valve (A1 extend) (8) Main control valve (9) F2.2 stack valve (10) Tool line relief valve (11) Attachment control valve (12) Attachment control valve (13) Tool line relief valve (14) Hydraulic oil cooler (15) Pilot manifold (18) Proportional reducing valve (Flow limit 2) (19) Proportional reducing valve (Flow limit 1) (20) Flow limit 1 pressure sensor (21) Flow limit 2 pressure sensor (22) Main relief valve (23) Hydraulic tank (24) Pilot relief valve (25) Pilot pump (26) Drive pump (27) Idler pump (28) Proportional reducing valve (power shift pressure)Two-Way / One Pump with electronic control is designed to allow complete electronic control over the work tool. This hydraulic system allows the operator to control a work tool with a two-way flow system with from one pump.Two-Way Flow from One Pump
Two-way flow from one pump can be achieved by selecting a work tool that requires two-way flow from one pump. The work tool can be selected through the monitor or by the work tool select switch. A typical example is a grapple that receives oil from one pump only.When one pump flow is required to the work tool, the pump supplying the oil can be programmed through the monitor. The following situations are listed to increase controllability of the work tool.
When the work tool with a boom and bucket operation is used most often, the idler pump is recommended as the supply pump.
When the work tool with a stick and swing operation is used most often, the drive pump is recommended as the supply pump.ReferenceRefer to Testing and Adjusting, "Work Tool Parameter - Program" for the tool control system to change the settings for work tool operation.ReferenceRefer to Testing and Adjusting, "Two-Way / One Pump - Electric Control: Default Value of Work Tool Parameters" for the Tool Control System to reference the factory settings.
Table 1
Operation Lever List    
Control     Extension     Retraction    
Right Joystick Thumbwheel     Push Forward     Push Backward    
Electric Foot Pedal     Push Forward     Push Backward    The following description is made under the assumption that the idler pump is supplying oil to the work tool.
Illustration 2 g03078243
Two-Way Flow from One Pump (idler pump) (5) Proportional reducing valve (A2 extend) (9) F2.2 stack valve (11) Attachment control valve (12) Attachment control valve (23) Hydraulic tank (25) Pilot pump (26) Drive pump (27) Idler pumpWhen the device for activation listed in Table 1 is pushed forward, the machine ECM sends a modulated signal to proportional reducing valve (5). Proportional reducing valve (5) allows pilot oil to flow to the attachment control valve (12). Attachment control valve (12) shifts, allowing high pressure from the idler pump to flow to the work tool.Oil returning from the work tool flows back through attachment control valve (12) and back to the hydraulic tank.During