IMPLEMENT AND STEERING HYDRAULIC SYSTEM CONTINUED
b. Bulldozer Lift Control Valve (Raise)
When pilot control pressure causes the control valve spool to move to the RAISE position, cylinder oil from rod end
passage flows through the passage to the chamber. The oil now becomes signal oil. Some of the signal oil flows
through an orifice to spring chamber #1 that is behind the flow control valve. Then, flow control valve moves to the
left. The remaining signal oil moves to the resolver and the signal oil flows through passage #1 to the previous
control valve. Then, the signal oil flows to the inlet manifold which sends signal oil to the compensator valve in
order to upstroke the pump.
The increased pump oil flows to the inlet passage and through the metering slots to chamber #2 and the load
check valve opens. The oil through the load check valve flows to passage #2, around control valve spool, and out
of the rod end passage to the rod end of the lift cylinders. The bulldozer blade raises.
Return oil from the head end of the lift cylinders comes through the head end passage, around the control valve
spool, and through the outlet passage to the tank.
Figure 28. Bulldozer Lift Control Valve (RAISE).