The steering wheel is heavy and sunken, perhaps because the system is wrong

Trucks often need to change their direction of travel in order to get to their destination in accordance with the driver's wishes. The mechanism used to change the direction of travel is called the steering system, and it affects the safety of the vehicle. If we find that the steering wheel becomes heavier and the steering sensitivity decreases in our daily driving, it is likely that there is a problem with the steering power system in the steering mechanism.

What is a power steering system?

The most common power steering system on trucks today is the mechanical hydraulic power steering system, with the main components being a hydraulic pump, oil pipe, pressure fluid control valve, V-drive belt, oil reservoir and so on. This type of power assist converts part of the engine power output into hydraulic pump pressure, which exerts an auxiliary force on the steering system, thus making the tyres steer.

Since mechanical hydraulic assistance requires significant consumption of engine power whether the vehicle is steered or not, improvements have been made to mechanical hydraulic assistance to develop a more energy-efficient electro-hydraulic power steering system.

The steering pump is no longer driven directly by the engine, but by an electric motor, and an electronic control unit has been added to the previous system, which calculates the optimum steering assistance force based on signals such as the vehicle's driving speed and steering angle. More and more heavy trucks are now being fitted with electro-hydraulic power steering systems.

When a part of the power-assisted system fails, the comfort and flexibility of the steering is lost, causing the driver to be more physically exhausted and unable to adjust the direction in time for danger.

Problems with the steering assistance system may be due to these causes

Damaged power steering pump: The power steering pump is the source of force for the power steering system and serves to create high pressure within the steering system to drive the steering. If the booster pump is faulty and unable to provide normal working pressure to the system then the steering wheel will turn heavily.

Insufficient hydraulic fluid: A lack of hydraulic fluid not only causes steering difficulties, but also prevents other parts of the system from achieving sufficient lubrication and causes strange noises and wear.

Hydraulic oil deterioration or impurities in the oil: hydraulic oil has a certain service life, if not replaced for a long time, it will easily cause the hydraulic oil to deteriorate and the viscosity of the oil to increase. In turn, the flow of fluid in the pipeline is slow, the system performance is affected, affecting the efficiency of the steering power, and may even lead to damage to the power pump.

Air in the hydraulic line: A lack of oil in the reservoir, poor sealing of the oil seal or incorrect operation when changing the hydraulic oil can cause air to enter the booster system. If there is air in the hydraulic fluid, then it will be unstable when transferring torque. For example, the working power of the booster system is interrupted when turning and the steering wheel is not steered coherently, so air is not allowed to be present in the steering booster unit.

Filter element blockage: The filter element in the filter is not maintained and replaced for a long time, which will cause blockage. When the filter element is blocked, the hydraulic oil will not circulate smoothly and the pressure of the return oil will become larger, which will also make the steering wheel heavy and thus lead to the occurrence of faults such as oil leakage from the oil seal at the steering input.