DISC 3641290 - Caterpillar

HOLD Position
Illustration 1 g02001715
(1) Spool (2) Spring (3) Pump passageThe lift control valve is located between the tilt control valve and the inlet manifold. In the HOLD position, spring (2) keeps spool (1) in the centered position. Oil from the pump flows into passage (3). In the HOLD position, spool (1) blocks the flow of oil.LOWER Position
Illustration 2 g02009696
(1) Plug (2) Port to the head side of the cylinder (3) Compensator spool (4) Chamber (5) Port to the rod end of the cylinder (6) Plug (7) Passage (8) Passage (9) Passage (10) Ball (11) Spring (12) Spool (13) Pump passage (14) Passage (15) Passage (16) PassageWhen you move the spool (12) to the left, the spring (11) is compressed toward the left. Oil from the pump flows into passage (13). The oil flows around spool (12) into passage (14). As the oil flows into passage (14), the oil acts against the compensator spool (3). As the oil pressure increases, the spring of compensator (3) compresses and the compensator spool moves up.The oil flows through the compensator spool (3) into passage (8). The oil pressure in chamber (4) and the pressure of the spring of compensator (3) balances oil pressure in passage (14) .When the oil enters passage (8), oil on the left side of passage is blocked by spool (12). On the right side of passage (8), the oil flows around spool (12) into passage (7). The oil then flows through port (5) to the rod end of the