OPERATOR AR-OPEN ROPS 2908187 - Caterpillar

Illustration 1 g06015406
Hydraulic schematic (negative flow control)
(1) Center bypass passage
(2) Center bypass passage
(3) Passage
(4) Passage
(5) Orifice
(6) Relief valve (negative flow control)
(7) Negative flow control line
(8) Orifice
(9) Negative flow control line
(10) Relief valve (negative flow control)
(11) Return passage
(12) Drive pump
(13) Idler pump
(22) Return line
(23) Port
Illustration 2 g01436671
Main control valves (rear view)
(7) Negative flow control line
(9) Negative flow control lineWhen cylinders or motors are not in operation, negative flow control pressure flows from center bypass passage (1) and center bypass passage (2). When fine control of the pilot control valves is needed, negative flow control oil flows from center bypass passage (1) and center bypass passage (2).
Illustration 3 g01436673
Relief valve (negative flow control) (stick II control valve)
(3) Passage
(4) Passage
(8) Orifice
(10) Relief valve (negative flow control)
(11) Return passage
(14) Plug
(15) Spring
(16) Body
(17) Valve
(23) PortOil flow from drive pump (12) goes to center bypass passage (2). The oil then goes through passage (3) and orifice (8) to return passage (22). Orifice (8) restricts the oil flow. The pressure in passage (3) increases. A negative flow control pressure now goes through passage (4) and negative flow control line (9) to the pump regulator. The negative flow control of the regulator causes the pump to destroke.Relief valve (10) consists of body (16), plug (14), valve (17) and spring (15).When the oil flow in a center bypass passage suddenly changes, there will be a sudden rise in the negative flow control pressure. Relief valve (10) allows part of the oil to flow by valve (17) and through return passage (11).When all controls are in NEUTRAL position, all of