ROD 6E0719 - Caterpillar

Illustration 3 g01427149
Right Side of Machine (14) Port "B" (15) Port "S" (16) Port "A" (17) Port "MA"Several ports are located on the top face of the tamper pump. Each of these ports is identified by a letter or an alpha numeric designation which is cast into the housing next to the port. Each port functions in the following way:
Port "A" (16) is a system port. Port "A" is the high pressure port when solenoid "C2" (5) is energized. On the tamper pump, supply oil flows out port "A" when the tamper is operating.
Port "B" (14) is a system port. Port "B" is the high pressure port when solenoid "C1" (7) is energized. Since solenoid "C1" is not used in the tamper system, port "B" is always the return port.
Port "L1" (not shown) is a case drain port. In the tamper system, case drain oil flows from port "L1" to the bypass manifold for the oil cooler.
Port "S" (15) is the suction port for the charge pump. The charge pump draws oil through the combined suction and return filter.The tamper pressure can be measured at the tap that is located in port "MA" (17) .Other important ports on the tamper pump include port "M4" and port "M5". The pressure on either side of the servo piston can be measured at these ports. Port "M4" is at the end of the servo piston on the side of the pump nearest solenoid "C2" (5). Port "M5" is located at the end of the servo piston on the side of the pump nearest solenoid "C1" (7). Port "M5" is pressurized when the tamper is operating.
Illustration 4 g01427150
Cross Section of the Tamper Pump (17) Charge pump (18) Servo piston (19) EDC (20) Feedback link (21) Servo springs (22) Swashplate (23) Slipper pad (24) Input shaft (25) Piston (26) Rotating groupEngine rotation turns the pump input shaft, which then rotates the rotating group. The rotating group contains a piston and barrel assembly. The pistons in the group rotate with the barrel assembly. The piston slipper pads allow the pistons to follow the angle of the swashplate. The rotating group only generates flow when the swashplate is not at zero angle. When the operator control unit sends an output signal to solenoid "C2" (5), the solenoid moves a spool. Spool movement directs oil into the chamber at one end of the servo piston (high pressure side). Also, spool movement opens the chamber to the case drain at the other end of the servo piston (low pressure side). Under these conditions, the servo piston moves. As the servo piston moves, the action of the control linkage causes the angle of the swashplate to change. As the swashplate moves, the feedback linkage tends to move the spool of solenoid "C2" back to neutral through an internal feedback spring. This action prevents the servo piston from tilting the swashplate too far by blocking the charge oil supply, once the tilt angle is equal to the input signal from the