WHEEL A 8D2269 - Caterpillar

Illustration 1 g01593204
Charge relief valve (1) Passage to case drain (2) Supply passage for charge oil from the charge pump (3) Port (4) Poppet (5) Seating surface of poppet (6) Spring retainer (7) Spring chamber (8) SpringCharge oil flows from the charge pump through the hydraulic oil filter into passage (2) . The oil then flows through passage (3) to poppet (4). When the pressure against surface (5) of poppet (4) overcomes the force of spring (8), poppet (4) moves to the left and the poppet pushes spring retainer (6) against the force of spring (8). Oil flows past poppet (4) into spring chamber (7). Then, the oil flows from spring chamber (7) through passage (1) to the case drain of the piston pump.Poppet (4) oscillates as the flow of charge oil fluctuates in order to maintain a constant pressure for the charge oil.