ROTATING GP-PUMP 1843957 - Caterpillar

Steering Control Valve - Neutral Position
Steering Control Valve In Neutral
(1) Check valve. (2) Inlet. (3) Ball resolver valve. (4) Outlet to tank. (5) Flow control valve. (6) Passage. (7) Pilot valve. (8) Passage. (9) Return passage. (10) Chamber. (11) Orifice. (12) Passage (from left neutralizer valve). (13) Spool. (14) Passage (from right neutralizer valve). (15) Metering orifices. (16) Passage. (17) Passage. (18) Outlet for left turn. (19) Outlet for right turn. (20) Metering orifices. (21) Spring.The flow of pilot oil to either end of the valve spool is stopped when; (a) rotation of steering wheel is stopped, or (b) the neutralizer valve stops the flow after a complete turn has been made. With no pilot oil flow against either end of the valve spool, spring (21) will keep the spool in its NEUTRAL position.
Location Of Steering Control ValveWhen the steering control valve is in its NEUTRAL position, the oil from the steering pump is stopped by the valve spool. The pressure increases in inlet passage (2). This pressure increase moves flow control valve (5). The flow control valve moves until oil can flow through it to outlet (4).In the NEUTRAL position, the valve spool also blocks (stops) the oil in the lines to the cylinders. This holds the machine in the turned position where the steering wheel was stopped. A very small amount of oil can still flow from outlets (18) and (19), through a bleed slot and then to return passage (9).The pressure of the oil in the blocked outlets (18) and (19) is felt through passages (8) and (6) and against pilot valve (7). If an outside force tries to turn the machine when the valve spool is in the NEUTRAL position, the increase in pressure will open pilot valve (7).The pressure in the lines will not go higher than the relief valve setting of 17 240 520 kPa (2500 75 psi). When the pilot flow to one end