A concrete plant reported that a XCMG LW300K wheel loader's steering felt "mushy." The steering wheel had to be turned almost 90 degrees before the wheels responded, especially when the engine was idling.
The technician first checked the "Steering Priority Valve." This valve ensures steering gets oil flow before the implement (lift) circuit. He removed the valve cartridge and found the "Pilot Filter Screen" inside the valve housing was completely clogged with red dust. The dust had bypassed the main hydraulic tank breather. The clogged screen restricted the pilot pressure needed to open the priority spool.
He then tested the "Steering Pump." It is a vane-type pump. He removed the pump housing. The "Rotor Vanes" were worn down by 1.5mm. The wear was caused by the contamination in the oil. The worn vanes could not seal properly against the cam ring, reducing the pump's volumetric efficiency at low RPM.
The repair involved ultrasonically cleaning the priority valve and replacing the hydraulic tank breather cap. The steering pump was replaced with a new unit. The system was filled with fresh hydraulic fluid. He also adjusted the "Orbitrol Stop Valves" to ensure no internal leakage. After the repair, the steering responded instantly to the wheel input.
