HOSE 3045250 - Caterpillar

The high-pressure relief valve functions to protect the circuit from high-pressure spikes. The valve also protects against damage to the circuit components if the POR valve malfunctions. Oil from the high-pressure side of the open circuit enters the valve at passages (8). Spring (6) forces spindle (7) against seat (11). The oil pressure acts against the force of spring (6). When the circuit pressure reaches the high-pressure relief setting, spindle (7) is lifted off seat (11). This movement instantly dumps high-pressure oil into the low-pressure side of the closed circuit.Makeup Check Valve
Illustration 8 g00468192
Multifunction Valve
(1) Cap. (2) Stud. (3) Locknut. (4) Spring. (5) Collar. (6) Spring. (7) Spindle. (8) Passage. (9) Poppet. (10) Seat. (11) Seat.
The multifunction valve has a second function. The valve acts as a makeup valve for the closed circuit. When the pressure in passages (8) (low-pressure side of the closed circuit) drops below the charge pressure, charge oil fills the closed circuit. Charge oil pressure on poppet (9) compresses spring (4). Poppet (9) is lifted off seat (10). Oil from the charge loop flows into the low-pressure side of the open circuit. When the pressure in the low-pressure side of the open circuit increases to charge pressure, the force of spring (6) closes poppet (9) on seat (10).Bypass Valve
Illustration 9 g00467876
Multifunction Valve
(1) Cap. (2) Stud. (3) Locknut. (4) Spring. (5) Collar. (6) Spring. (7) Spindle. (8) Passage. (9) Poppet. (10) Seat. (11) Seat.
The multifunction valve has a third function. The valve allows the machine to be towed. To tow the machine, loosen locknut (3) and turn stud (2) clockwise until the stud contacts with the top of collar (5). Spring (4) is compressed. Then turn stud (2) until the top of the stud is flush with locknut (3). Spindle (7) moves downward and the oil flows across seat (11). This action allows the oil to pass from one side of the closed circuit to the other side.Note: Brakes must be released prior to towing.Control Valve
Illustration 10 g00451114
Directional Control Valve
(1) Lever. (2) Spool. (3) Passage for charge oil. (4) Control valve body. (5) Servo valve lever.
The propel control lever delivers a mechanical input to lever (1). The input determines the amount of rotation of spool (2). The output of the propel pump is proportional from 0 to 100 percent. This measurement is based on the amount of charge oil that is allowed to flow from passage (3) through spool (2) and into the servo valve. Charge oil flows through passage (3) to the spool (2) and the oil is sent to either the right end of the servo valve or left end of the servo valve. The charge oil pressure shifts the servo valve, and a mechanical signal is sent to the swashplate. This action upstrokes the propel pump.Neutral Start Control
Illustration 11 g00485605
Location of Neutral Start Switch-on Propel Pump
(1) Neutral start switch.
Illustration 12 g00468995
Neutral Start Switch
(2) Spool. (3) Electrical switch. (4) Neutral start switch pin.
When the control valve spool (2) is centered properly, neutral start switch pin (4)