THEORY OF OPERATION - CONTINUED
The electro-hydraulic steering system provides three modes of steering control; two-wheel steer, four-wheel steer, and
The variable rate steering system utilizes two front and two rear hydraulic steer cylinders and electronic wheel position
sensors connected to an electronic control module to maintain direction and control. The variable rate system allows the
system to change or adjust to different modes of operation.
An emergency steering pump is provided in the event the engine is inoperative. If the engine quits while operating the
RTCH, the emergency steering pump provides sufficient hydraulic pressure to control the truck until it is brought to a
The brakes are totally enclosed within the front and rear drive axle housings, next to the wheel ends.
The brake system is a wet brake system that is comprised of three separate hydraulic circuits: service brake circuit, cool-
ing circuit, and parking brake circuit.
The brake system also includes six pressurized accumulators that provide adequate stored energy to stop the RTCH in
the event of engine shutdown.
The service brake circuit is applied by depressing either the left or right floor-mounted hydraulic brake pedals. Brake
pressure is applied to eight cylinders per side within the front axle and one cylinder per side in the rear axle.
The brake system cooling circuit cools the brake disks using oil pumped from the main hydraulic system through brake
chambers during operation.
The parking brake assemblies are mounted at the input flanges of the front and rear axles. The brakes are applied by
spring pressure and released hydraulically. A warning buzzer sounds if driver leaves seat without applying the parking
brakes. In the event of an emergency the parking brake may be utilized to stop the truck.
The RTCH hydraulic system is comprised of the following major components that provide hydraulic power to operate
and control the container tophandler, boom, steering, and brake systems. In addition the hydraulic system is used to place the
cab and bogie wheels into transport mode.
Three variable piston-type hydraulic pumps are driven by the transmission power take-off (PTO). The pumps provide
hydraulics for the steering system and tophandler.
One double vane-type pump is driven by the transmission PTO. It provides hydraulics for the boom cylinders, service,
and parking brake systems.
One single-vane pump is driven by the engine. It provides hydraulics for a cooling fan.
Main valves control the main hydraulics. The valves are controlled by an electro-hydraulic servo system from the joy-
stick control in the operators cab.
High-pressure oil filters clean hydraulic oil before returning oil to the reservoir. Breather filters allow venting of the
Hydraulic system oil cooler and fan maintain and control hydraulic oil temperature. The cooling fan is powered by
hydraulics from an engine-driven hydraulic pump.
Emergency systems: one ground-driven hydraulic pump maintains steering control in the event of engine failure; a 24-
volt electric hydraulic pump provides power to lower boom and release the twist locks in the event of engine failure.
The electric pump also provides a means to place the operators cab into the transport mode.