HYDRAULIC SYSTEM
ME12002 Hydraulic Pump General Description
531 532 611 613 621 625 626 643 646 652
Pivot point Servo pistons Lever linkage system Regulator body Pilot pistons Outer power springs Inner power springs Pilot pistons Control springs Main spools
Pump regulator operation uses a lever linkage system (611) that connects servo pistons (532), main spools (652) and regulator body (613). See Figure 3-20.
Figure 3-21 Pump General Description
Pilot pistons (621 and 643) and control springs (625, 626 and 646) activate the lever linkage system (611). The lever linkage system (611) ensures a highly responsive and accurate control system. See Figure 3-20.
531 532 874 875 897
Pivot point (531) connects servo piston (532) to pump swash plate (212). See Figure 3-20 for servo piston (532) and pivot point (531), and Figure 3-19 for swash plate (212).
Regulator assembly lever and linkage arrangements are shown in Figure 3-21. The main feedback lever is shown in the center of the pump where servo pivot (531) connects it to servo piston (532). See Figure 3-21.
Moving servo piston (532) to the left increases pump displacement and moving servo piston (532) to the right decreases pump displacement. See Figure 3-20.
Fixed pivot (874) connects main feedback lever to main spool (652). Feedback pivot (897) connects main feedback lever to displacement lever (right side) and power lever (left side). Fixed pivot pin (875) secures displacement lever (right side) to the regulator body, and fixed pivot (874) secures power lever (left side) to the regulator body. See Figure 3-21.
Servo piston (532) has an area ratio of 4:1. The smaller diameter area on the right side of the servo piston is continuously connected to the pump's outlet pressure. The larger diameter area on the left side of the servo piston (532) is fed from the main regulator spool (652). As the main regulator spool (652) pressurizes the left side of the servo piston, it continuously reduces the pump displacement. See Figure 3-20.
909768/BP1207
Pivot point Servo piston Fixed pivot Fixed pivot pin Feedback pivot
70
Printed in U.S.A
