CONT GP -E 20R8192 - Caterpillar

Float Position
VALVE SECTION FOR LIFT IN FLOAT POSITION
1. Passage from pump. 2. Passage to next valve section. 3. Passage from pump. 4. Valve spool (in FLOAT position). 5. Passage to tank. 6. Passage from pump. 7. Check valve. 8. Make-up valve. 9. Passage to head ends of lift cylinders. 10. Passage to rod ends of lift cylinders.A detent on the end of valve spool (4) (not shown) holds the valve spool in the FLOAT position. The operator must move the lever to get the valve spool out of the detent for the FLOAT position.When valve spool (4) is in FLOAT position, the pump oil goes through passages (1) and (3) into passage (2), through the next valve sections and to passage (5). The position of valve spool (4) lets the pump oil in passage (5) go to both passages (9) and (10), to the rod ends and head ends of the lift cylinders. With the pump oil in both ends of the lift cylinders at the same pressure and passages (9) and (10) open to the tank through passage (5), the position of the angling frame assembly and bulldozer is not controlled by the pump oil.With the control lever and valve spool (4) in FLOAT position, the weight of the frame and bulldozer is the only controlling force.Make-Up Valve
The make-up valve is in the control valve section for lift. The make-up valve is in passage (2) to the head ends of the lift cylinders.A spring (1) and oil pressure in the spring chamber hold the valve closed. The valve opens only when the flow of pump oil to the head ends of the lift cylinders is not enough when the control valve spool is in either the FLOAT or LOWER position. When the flow of oil to the head ends of the cylinders is not enough, the pressure of the oil in passage (2) is low. The higher pressure of the oil in the passage to the tank opens the valve and lets more oil to the head ends of the cylinders.
MAKE-UP VALVE
1. Spring. 2. Passage to head ends of lift cylinders. 3. Valve in CLOSED position. 4. Valve in OPEN position.Relief Valve
The location of the relief valve is in the inlet section of the control assembly. The setting of the relief valve is approximately 2500 psi (175.7 kg/cm2).
RELIEF VALVE CROSS SECTION
1. Passage to spring chamber. 2. Valve. 3. Spring. 4. Passage to tank. 5. Pilot valve. 6. Spring. 7. Screw for adjustment. 8. Locknuts.The relief valve is a pilot-type valve. Pump oil, through passage (1) into the spring chamber, and spring (3) hold valve (2) closed. The pressure of the pump oil is againt pilot valve (5) which is held closed by spring (6).Pump oil in spring (3) chamber with more pressure than the force of spring (6), holding pilot valve (5) closed, will open the pilot valve. The oil in spring (3) chamber goes through the open pilot valve and through passage (4) to the tank,