Broderson RT-400-A, Operation And Maintenance Manual

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CONTROL AND HYDRAULIC SYSTEM
The RT-400 control system is a pilot-actuated hydraulic system that is supplied with flow by two
variable displacement pumps. The pumps are mounted on and driven by the transmission and
supply flow on demand. The control joysticks are single axis levers mounted on each side of
the operator seat. The pilot joysticks will only be provided with pilot pressure and be able to
transmit that pilot pressure to the control valves when the seat switch and the ARM command
are activated.
The pump on the curb side of the machine,
P1
, supplies the three-spool upper control valve
mounted on the turntable. This valve controls the hoist, boom extension, and the boom topping
functions.
The pump on the road side of the machine,
P2
, supplies the outrigger control valve, lower con-
trol valve, braking, and steering circuits. The lower control valve is located below the operator
station mounted to the chassis. The outrigger control valve is mounted inside the chassis on
the road side of the machine. The braking and steering circuits are sourced through the priority
manifold, which is mounted inside the chassis on the curb side of the machine.
The
P2
pump flow is also passed through the hydraulic swivel and combined with the flow from
P1
to supply the upper control valve.
If the brake system pressures are low, the unloading valve shifts and allows flow into the brake
system accumulators. The two accumulators are separated in a front/back split, such that each
provides fluid either to the front or rear brakes. Flow and pressure to the wet disc brakes is con-
trolled by a valve directly connected to the foot pedal in the cab.
The schematic of the hydraulic system is shown on the following page.
.