SEAL-LIP TYPE 5367919 - Caterpillar

When the bulldozer control lever is moved to HOLD position, both the head end and the rod end passages of the bulldozer lift control valve are blocked. The oil that is in passages (2) and (12) is blocked.Bulldozer Control Lever in the RAISE Position
Illustration 4 g00854955
Quick-drop valve with the bulldozer control lever in the RAISE position (1) Cover (2) Passage to the head ends of the lift cylinders (3) Passage (4) Passage (5) Passage to the LOWER port of the control valve (6) Valve spool (7) Spring (8) Cover (9) Plunger (10) Orifice sleeve (11) Passage to RAISE port of the control valve (12) Passage to the rod ends of the lift cylindersWhen the bulldozer control lever is moved to RAISE position, pump oil enters the quick-drop valve at passage (11) . The oil flow moves orifice sleeve (10) to the right. The oil flows past orifice sleeve (10) and out passage (12) to the rod ends of the bulldozer lift cylinders. Return oil from the head ends of the cylinders enters the valve at passage (2) . The oil flows past spool (6) and out passage (5) to the control valve.The circuit pressure on the left end of plunger (9) keeps the plunger shifted to the right. Hydraulic circuit pressure also increases in passage (4) to the right end of spool (6) . The pressure on the right end of the spool is equal to the pressure on the left end. Therefore, spring (7) keeps spool (6) shifted to the right.Bulldozer Control Lever in the Slow LOWER Position
Illustration 5 g00854962
Quick-drop valve with the bulldozer control lever in the slow LOWER position (1) Cover (2) Passage to the head ends of the lift cylinders (3) Passage (4) Passage (5) Passage to the LOWER port of the control valve (6) Valve spool (7) Spring (8) Cover (9) Plunger (10) Orifice sleeve (11) Passage to RAISE port of the control valve (12) Passage to the rod ends of the lift cylindersThe bulldozer control lever is moved to the LOWER position below 75 percent of the maximum travel. The blade lowers at a slow speed. Return oil from the rod end of the bulldozer lift cylinders enters the quick-drop valve at passage (12) . The return oil flows past orifice sleeve (10) and out passage (11) to the control valve. The return oil flow moves orifice sleeve (10) to the left against a retaining ring. A pressure drop in the return oil is set up across orifice sleeve (10) .Pump oil enters the valve at passage (5) . The pump oil flows past spool (6) and out passage (2) to the head ends of the cylinders. Pump oil flow enters passage (3) in spool (6) , which raises the pressure on the right end of plunger (9) . However, the