HYDRAULIC STEERING SYSTEM
1. General. The hydraulic steering system has two functions. The primary purpose is for steering the roller.
The steering pump receives oil from the hydraulic oil tank after it has been cleaned by a hydraulic filter. Oil
from the steering pump flows through a priority valve and continues on in two directions. The primary path
for the oil is to the steering control unit. The steering control unit sends hydraulic oil to the steering cylinders.
When the steering wheel is turned, the steering control unit sends hydraulic oil through the steering hydraulic
lines to force the steering cylinders to turn the roller.
The secondary flow of oil and return oil from the steering control unit is combined with the parking brake and
two-speed shift manifold by way of an oil line. This oil is used for the charge system. The charge system
supplies the control circuit and replenished the main closed loop and cooling circuit of the vibratory system.
2. Steering Control Unit. The steering control unit is a spring-centered, non-load, reaction-type pump which
sends pressurized hydraulic oil to the steering cylinders. The steering control unit has two sections: the
control section and the metering section. Oil from the steering pumps goes into the control section. As the
steering wheel is turned, the control sends oil out from the metering section. Metered oil from the metering
section is directed by the control section to either the left turn port or right turn port.
3. Steering Pump. The steering pump is a gear-type mounted to the accessory drive on the engine and turns
clockwise as the engine is running. The steering pump supplies pressurized hydraulic oil to the steering
system and charge oil to the propel and vibratory systems. A priority valve gives the steering system priority
over the propel charge circuits. A pressure compensator valve regulates a constant six gallons per minute
flow to the steering system.
4. Priority Valve. Inside the steering is the priority valve which is a pressure compensated flow divider. The
priority valve divides flow between the steering circuit and the propel charge circuits. The steering circuit
5. Brake/Shift Manifold Valve. The brake/shift manifold valve is part of the propel system, yet receives it
charge from the steering pump.
6. Steering Cylinders. The steering cylinders are piston-type hydraulic cylinders mounted at the pivot joint of
the frame and yoke assemblies. When the steering control unit sends pressurized oil to them, the steering
cylinders force the yoke assembly to shift its relative placement on the frame assembly, causing the roller
to steer either left or right.
7. Fuel/Hydraulic Oil Tank. The fuel/hydraulic oil tank consists of the hydraulic tank (located on the left-side)
and the fuel tank (located on the right-side). Although the tanks are welded together, they are separate in
their function. The CB534B Roller hydraulic oil tank holds 15.5 gal (59 Liters) of hydraulic oil. The CB534C
Roller hydraulic oil tank holds 24 gal (91 Liters) of hydraulic oil.
8. Hydraulic Oil Filter. The hydraulic oil filter cleans all hydraulic oil used in the propel, vibratory and steering
systems. When the filter element is clogged, or oil is cold, the bypass valve opens and oil flows past the
element and a signal is sent to the warning light. On the CB534B roller, an indicator is mounted on the filter
assembly to display the condition of the filter element.