LEVELING BLADE Caterpillar

A. Blade/Steering System Pump

1. A vane-type pump powers the blade and steering systems of both machines. On earlier 320A's, the pump is on the right of the engine; on later models, it's on the rear of the propulsion pump. The 420C has it on the drive end of the engine. The pump has a priority valve which sends primary output to the steering system; fluid in excess of that needed for steering powers the blade system. The pump has an integral relief valve for the primary flow which opens at 2000 psi (13,790 kPa). Relief for the blade system is in the blade control valve.

B. Blade Control Valve

1. This valve, at the operator's right, directs hydraulic fluid to the head or rod ends of the blade cylinders, thus controlling the up and down movement of the blade. The relief valve in this valve opens at 1250 psi (8619 kPa).

C. Blade Cylinders

1. The blade cylinders at the right and left ends of the blade extend to lower the blade and retract to raise it.

D. Blade

1. The blade, for moving and levelling fill material, has a removeable cutting edge.