HOUSING GP-FLYWHEEL 3297881 - Caterpillar

Attachment Control Valve (Optional)
Valve Section For Attachment (HOLD Position)
(1) Relief valve for attachment circuit. (2) Passage to head end of attachment cylinder. (3) Check valve. (4) Passage from pump. (5) Passage to rod end of attachment cylinder. (6) Relief valve for attachment circuit. (7) Valve spool. (8) Passage from pump. (9) Passage to next section. (10) Passage from pump. (11) Passage to tank. (12) Spring.Attachment Valve HOLD Position
The location of the attachment control valve section is between the control valve section for tilt and the end manifold. The attachment control valve is (optional equipment). The pump oil from the valve section for tilt goes into passage (4). Passage (4) is a common passage through the sections of the control valve. Passage (4) has no outlet.If pump oil from passage (9) of the valve section for tilt goes into passages (10) and (8) of the valve section for tilt, the oil will go around the valve spool into passage (9). The oil in passage (9) goes into the next valve section or the manifold. A passage in the manifold connects passages (9) and (11) of the last valve section. Passage (11) is a common passage through the valve sections to the tank.The HOLD position of valve spool (7) stops the oil in passages (2) and (5). With the oil in the circuits to the coupler cylinder stopped, the cylinder can not move until the control lever and valve spool (7) are moved to either the OPEN or CLOSED position.Spring (12) on the end of valve spool (7) is compressed when the control lever is moved to either the OPEN or CLOSED position. The spring will move valve spool (7) and the control lever to the HOLD position when the lever is released.Attachment Valve OPEN Position
When the control lever moves valve spool (7) to the OPEN position (not shown), the pump oil in passages (10) and (8) can not go into passage (9), through the manifold and through passages (11) to the tank.The oil in passage (4) gets an increase in pressure which opens check valve (3). The pump oil in passage (4) goes through the open check valve into passage (2) and to the head end of the attachment cylinder. If there is no supply oil to passages (10) and (8) (blocked by either tilt or lift lever), pressure has already had an increase in passage (4).The pump oil going into the head end of the attachment cylinder extends the cylinder rod outward. The oil from the rod end of the cylinder goes through passage (5) and then through passage (11) to the filter and tank.Attachment Valve CLOSED Position
When the valve spool is in the CLOSED position (not shown) the pump oil in passage (4) opens check valve (3) and the flow of pump oil is through passage (5) to the rod ends of the attachment cylinder. The oil from the head end of the attachment cylinder goes through passage (2), through passage (11) and to the filter and