GEAR 0036664 - Caterpillar

CLOSED Position
Illustration 1 g01401083
Line relief valve in the CLOSED position
(1) Adjustment screw
(2) Locknut
(3) Chamber
(4) Spring
(5) Port
(6) Seat
(7) Passage
(8) Poppet
(9) Spring chamber
(10) Orifice
(11) Spring
(12) Spring
(13) Passage
(14) Port
(15) Passage
(16) Valve
(17) Port to the head end of the ripper cylinders
(18) Passage Poppet (8) is forced downward against seat (6) by the force of spring (4). Valve (16) is forced downward by the force of spring (11) and by the force of spring (12).System pressure oil in passage (18) flows through passage (13) into spring chamber (9). The force of the system pressure oil acts on poppet (8). When the force of system pressure oil in passage (18) is less than the force of spring (4), poppet (8) remains against seat (6). The pressure in passage (18) and the pressure in spring chamber (9) are now equal. System pressure oil in spring chamber (9) and the combined force of spring (11) and of spring (12) maintain the position of valve (16). There is no oil flow from passage (18) to passage (15) through port (14). When system oil pressure in passage (18) is less than the line relief pressure setting, the line relief valve remains in the CLOSED position.OPEN Position
Illustration 2 g01401255
Line relief valve in the OPEN position
(1) Adjustment screw
(2) Locknut
(3) Chamber
(4) Spring
(5) Port
(6) Seat
(7) Passage
(8) Poppet
(9) Spring chamber
(10) Orifice
(11) Spring
(12) Spring
(13) Passage
(14) Port
(15) Passage
(16) Valve
(17) Port to the head end of the ripper cylinders
(18) Passage System oil pressure in passage (18) and spring chamber (9) nears the line relief valve pressure setting. The force of the system oil pressure in spring chamber (9) becomes greater than the force of spring (4). The system oil pressure in spring chamber (9) forces poppet (8) away from seat (6). System oil pressure now flows through orifice (10) of seat (6) into chamber (3). The oil in chamber (3) now flows through port (5) and through passage (7) into passage (15). This low-pressure oil now returns to the hydraulic tank.At the same time as the oil in spring chamber (9) flows through seat (6), the system pressure oil in passage (18) flows through passage (13). As the system oil pressure flows through orifice (13) into spring chamber (9), the pressure of the oil in spring chamber (9) decreases. The reduced pressure oil in spring chamber (9) allows the high-pressure oil in passage (18) to force valve (16) upward . The high-pressure oil in passage (18) now flows through port (14) into passage (15). The oil flows from passage (15) through the return oil passage back to the hydraulic tank.The amount of spring force of spring (4) that acts on poppet (8) determines the main relief valve pressure setting. Adjustments to the main relief valve pressure setting are made by changing the spring force of spring (4). The position of adjustment screw (1) determines the spring force of spring (4).Reference: Refer to Specifications, Systems Operation, Testing and Adjusting, "Relief Valve (Line) - Test and Adjust" for adjustment procedures.