The steering unit is part of the hydrostatic power steering system. Usually the steering unit is connected to the steering wheel through a steering column. During the steering, the steering wheel moves a gear with outer cogs which has an orbital movement respect to the outer toothed gear. Inside the steering unit, the rotor, which has the function of volumetric dosing unit, releases an amount of oil that is proportional to the turning angle made by the steering wheel. The distribution is controlled by a special rotating dispenser which is coaxial respect to the steering column (sleeve valve).
When the steering system works in hydraulic modality, the torque requested to the steering wheel is very low because the energy necessary to steer is provided by the pressing/flowing fluid. This allows an easier and a more reliable directional control of the vehicle.
In case of emergency (for example a breakdown in the pump or a lack of pressing fluid) the steering unit works as a manual pump allowing the operator to control the vehicle even in disadvantaged conditions (obviously applying a stronger torque to the steering wheel).
OGNIBENE POWER steering units can be easily installed on both low and high power vehicles (tractors, forklift trucks, material handling vehicles and industrial machinery in general, municipal and garden tractors, etc.) and can be customized completely according to customers’ specific needs.
There are many different configurations for every type of steering unit, according to the kind of displacement and pressure load required by the vehicle. In addition, the single steering unit can be equipped with one or more valves (for example check valves, shock valves, suction valves etc.) in order to improve the performance of the vehicle.
OGNIBENE POWER steering units allow to control the steering wheel in every driving situation therefore they guarantee a reliable performance and a safer and more comfortable driving experience.
Steering valves can be categorized according to their peculiarities:
OPEN CENTER STEERING UNIT
The open center steering unit, when it is in a neutral position, has an internal connection that carries out an operation of short circuit of the fluid from the pump directly to the tank with a low pressure drop. The NON REACTIVE version (ON) prevents the external forces passing from the ground to the wheels to arrive to the steering wheel. The REACTIVE version (OR) instead let the forces pass through, causing a reaction to the steering wheel that is proportional to the movement the steering cylinder. This latter version requires the same volumes in both the two chambers of the cylinder.
CLOSED CENTER STEERING UNIT
The closed center steering unit is characterized, in neutral position, by the interruption of the connection between pump and tank. Also this kind of steering unit can be reactive (CO) or non reactive (CN).
LOAD SENSING STEERING UNIT (LS)
This unit is a closed center steering unit equipped with an oil port providing a pressure signal (static or dynamic) able to control a flanged priority valve (VPF) or in-line priority valve (VPL). This system allows controlling the flow rate necessary to make the steering unit work correctly. It can be non reactive (LS) or reactive (LSR).
POWER BEYOND (PB)
The most important characteristic of a Power Beyond steering valve is that it can supply oil for steering autonomously without using flow dividers or priority valves. This has the advantage that all can be comprised into small space.
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