Let's discuss the common problem of heavy steering in loaders, and how to troubleshoot and resolve it.
Loaders use a flow amplification steering system, consisting of a priority flow amplification valve and a fully hydraulic steering gear. Heavy steering can manifest in two ways: either the steering wheel itself is heavy, or the steering wheel turns freely, but the entire machine still feels heavy.
Heavy steering is generally caused by a pilot system malfunction. Check the pilot system's pressure, pipe connections, and pipe joints for problems. If the steering wheel turns freely but the entire machine still feels heavy, it's generally caused by a steering system malfunction. Check the pipe connections, oil suction line, steering system pressure, and hydraulic cylinders for problems.
Before measuring and adjusting the system pressure, park the machine on a level surface, lower the boom, level the bucket, and turn off the engine to ensure safety. Before measuring the pilot pressure, lower the boom to its lowest position and retract the bucket to its maximum angle. Before measuring the steering pressure, remove the hydraulic limit rod.
The normal pilot pressure is: no less than 2.2 MPa at idle throttle and no more than 5 MPa at high throttle. When measuring steering pressure, the vehicle must be turned to a large turning angle, in the mechanical limit position, and the steering wheel must be in the steering position. At high throttle, the steering system pressure should reach 15 MPa.
If either of these measured pressures does not meet the specified values, readjustment is required. Adjusting the pilot pressure involves adjusting the overflow valve at the rear of the dual pump. Adjusting the steering pressure involves adjusting the end of the priority flow amplification valve.
Check the pipe connections for correctness. This is mainly true for older vehicles. In this case, focus on checking the pilot pump return oil and limit valve return oil connections for correctness. Incorrect return oil connections can easily cause increased back pressure and heavy steering effort. Also check the suction line for air intake or leaks.
Check for blockages at pipe joints. Blockages in pipes or joints due to dirt can easily cause increased back pressure and heavy steering effort.
To check for internal leakage in the hydraulic cylinder, retract the piston to the bottom of the cylinder, disconnect the rodless chamber oil pipe, and continue filling the rod chamber with oil. If a significant amount of oil leaks from the rodless chamber oil port, it indicates that the piston seal ring is damaged and should be replaced. If there is internal leakage in the cylinder, the steering system pressure will generally be low, and steering will be weak.
