CONTROL GP-TRANSMISSION HYD 8P3046 - Caterpillar

Attachment Control Valve OPEN Position
When the control lever moves valve spool (7) to the right into the OPEN position, pump oil flow from passage (9) into passages (8) and (10) is blocked. The pump oil in port (4) increases in pressure until it opens check valve (3). When the check valve opens, the pump oil in port (4) flows through the open check valve into port (2) and on to the head ends of the attachment cylinders.The pump oil going into the head end of the attachment cylinders extends the rods outward. The oil from the rod ends of the cylinders flows through port (5) and then through passage (11) back to the filter and tank.Attachment Control Valve CLOSED Position
When the control lever moves valve spool (7) to the left into the CLOSED position, pump oil flow from passage (9) into passages (8) and (10) is blocked. The oil in port (4) increases in pressure until it opens check valve (3). When the check valve opens, the pump oil in port (4) flows through the open check valve into port (5) and on to the rod ends of the attachment cylinders.The pump oil flowing into the rod ends of the attachment cylinders retracts the rods inward. The oil from the head ends of the cylinder flows through port (2) and then through passage (11) to the filter and tank.Relief Valves
Attachment Circuit Relief Valves
(Lever in OPEN Position) (2) Port. (11) Passage to tank. (13) Piston. (14) Passage. (15) Passage. (16) Spring.The two attachment relief valves are mounted in the attachment control valve. The setting for both the rod end and the head end circuits is 25 500 350 kPa (3700 50 psi).If the pump oil pressure in port (2) becomes greater than the return oil pressure in spring (16) chamber plus the force of spring (16), then piston (13) moves left. Some of the pump oil from port (2) now flows through passage (15) and passage (14) into passage (11). Oil flows through passage (11) back to tank.The relief valve in port (5) works in the same manner.Kickout Systems
Lift Kickout
Lift Kickout And Bucket Positioner Components
(1) Switch holder assembly. (2) Solid state switch (normally closed). (3) Magnet assembly. (4) Tube assembly. (5) Switch holder assembly. (6) Magnet assembly.
Lift Control Valve Components - Typical Example
(7) Lift control valve spool. (8) Spring. (9) Electromagnet detent. (10) Connector to solid state switch.The lift kickout group consists of solid state switch (2) (located on right side of the loader frame), magnet assembly (3) (located on lift arm pivot) and electromagnet detent (9) (part of the lift control valve).Solid state switch (2) is normally closed and only opens when magnet assembly (3) makes contact.When the operator moves the lift control lever to the RAISE position, the bottom of control valve spool (4) contacts energized electromagnet (9). The electromagnet will hold lift control lever in RAISE position.As the bucket lifts, magnet assembly (3) on the lift arm pivot moves in the direction of normally