SENSOR GP-POSITION 2306268 - Caterpillar

Introduction
For Specifications with illustrations, make reference to PUSH-PULL HYDRAULIC SYSTEM FOR 627-637-657 TRACTORS, Form No. REG01611. If the Specifications in Form REG01611 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications in the book with the latest date.Hydraulic System
BASIC PUSH-PULL HYDRAULIC SYSTEM-SCHEMATIC (Engine Operating and Bail Raised-Lockdown)
1. Bail position cushion-hitch selector valve. 2. Selector valve spool. 3. Bail. 4. Line from cushion-hitch pump. 5. Control valve. 6. Signal oil pressure control valve. 7. Push-Pull oil pump. 8. Directional valve spool. 9. Signal oil line. 10. Poppet valve. 11. Shuttle valve. 12. Pilot valve. 13. Dump valve. 14. Hydraulic cylinder.When the machine is equipped with both Push-Pull and Cushion-Hitch the selector valve gets signal oil pressure from the Cushion-Hitch circuit through line (4). When the machine is equipped with only Push-Pull, signal oil pressure comes from control valve (5) for selector valve (1) operation.The Push-Pull hydraulic system uses the hydraulic oil in the tractor hydraulic tank. The tractor operator controls the position of the Push-Pull bail by moving the lever on the bail position selector valve. The bail control lever is held in the desired position by detents in the selector valve spool. The selector valve is a three position valve; bail raise (cushion ride), bail raise (lockdown) and bail lower (lockdown).Machines With Poppet Valves In Cylinder
The Push-Pull hydraulic pump sends pressure oil to control valve (5) and the rod end of bail hydraulic cylinder (14) when the bail is raised. Three poppet valves (10) in the hydraulic cylinder piston, are pushed open as the piston "bottoms" in the head end of cylinder when the bail raises to the limit. With the poppet valves open, the oil pressure in the rod end of the cylinder is greatly reduced.When the bail control lever is moved to the LOWER position, the lever moves the spool to the third detent. The spool in this position sends "signal oil" through line (9) to control valve (5). The signal oil pressure moves directional spool (8) to the left, compressing the spring, to a position which sends the pump pressure oil to the head end of hydraulic cylinder (14). The pressure oil in the head end pushes the piston and extends the rod to lower the bail. Shuttle valve (11), in the circuit between the rod end of the cylinder and the tank, prevents the combined weight of the bail assembly and bail down pump pressure from lowering the bail at a high rate.The shuttle valve (11) is operative only in the BAIL LOWER position. When the bail is lowered, return oil from the rod end of hydraulic cylinder (14) moves the shuttle valve (11) to the left. This allows return oil to be metered, through the orifices, to the tank. Should an external force occur, such as the rear machine raising or the front machine dropping, the bail will try to lower. At this