FLOOR MAT 2514245 - Caterpillar

HOLD Position
Illustration 1 g02969596
(1) Spring
(2) Control Spool
(3) Load sense signal passage
(4) Pressure compensator
(5) Makeup and relief valve
(6) Passage to workport (A) for the head end of the cylinder
(7) Passage to workport (B) for the rod end of the cylinder
(8) Bridge passage
(9) Spring
(10) Solenoid valve for workport (B)
(11) Return passage to tank
(12) Joystick thumbwheel
(13) Pump supply port
(14) Feeder passage
(15) Machine ECM
(16) Solenoid valve for workport (A)
(17) Pilot supply oil
(18) Pilot supply oil
Illustration 2 g02970959In the HOLD position, the spring (1) and spring (9) hold spool (2) in the centered position. No pilot oil enters the control valve. Any pilot oil in the pilot lines drains through the pilot valve to the tank. Spool (2) blocks the flow of pump supply oil in passage (13).Passage (13) is common to all control valves in the bank valve. The passage has no outlet. The spool blocks the flow of pump supply oil until the operator moves the thumbwheel on joystick (12).Flow to Port A
When the operator moves the switch (D) on the joystick to position (A), a signal is sent to machine ECM (15). The machine ECM sends a signal to actuate solenoid valve (16). Pilot oil is present at solenoids (17) and (18). When solenoid (16) is actuated, pilot pressure acts on the left end of control spool (2). When the oil overcomes the force of spring (9), spool (2) moves right.Pump supply oil flows from passage (13) around the spool to passage (14). The hydraulic oil from passage (14) flows to the pressure compensator valve (4). In the pressure compensator valve, the hydraulic oil flows into internal passages. The pressure compensator valve moves up. As the pressure compensator valve moves up, Oils flows around the compensator to bridge passage (8). Some of the hydraulic oil in passage (8) will flow into load sense signal passage (3). The hydraulic oil that flows to passage (3) is signal oil. The signal oil balances the pressure compensator valve against the hydraulic oil pressure in passage (14). This pressure balance controls the flow across spool (2).The signal oil flows to the pressure compensator valve in each control valve. The signal oil also flows to the pump control valve on the hydraulic pump. The signal oil helps to control the output of the hydraulic pump. The hydraulic pump upstrokes and the hydraulic oil pressure in passage (13) and passage (14) increases.In right-hand side passage (8), spool (2) blocks the flow of the oil to passage (7). In left-hand passage (8), the hydraulic oil flows around the spool (2) into passage (6). The hydraulic oil flows through passage (6) and workport (A).If the machine contains a multipurpose bucket, the oil flows through workport (A) to the head end of the multipurpose bucket cylinders. If work tools are installed on the