Insufficient Oil in the Hydraulic Tank
This is the most basic yet easily overlooked fault in the lifting system, which directly affects the lifting power output. Specifically, the carriage lifts slowly and weakly or even fails to lift at all, accompanied by a buzzing noise from the hydraulic pump. Long-term oil shortage will cause idling and cavitation of the pump body.
The main causes are that the driver does not check the oil level regularly, hidden leakage in the hydraulic system is not found in time, or the oil level does not reach the standard mark and air is mixed in during refueling.
Insufficient oil will accelerate the wear of the hydraulic pump and the distributing valve, forming a vicious cycle: oil shortage → wear → aggravated failure. Therefore, drivers should develop a habit of regular inspection and oil replenishment in daily use.
The filter screen and pipelines are the key channels for hydraulic oil circulation. Once blocked, they will cut off the oil flow and cause lifting malfunctions.
Symptoms include no response or extremely slow lifting, increased pressure and overheating of the hydraulic pump, and in some cases, pipeline vibration and abnormal noise.
This is mainly because dump trailers often operate in dusty, gravel‑filled environments where impurities mix into the hydraulic oil, and the filter screen is not replaced in a timely manner. Pipelines may also develop rust or sludge after long‑term use, or become deformed due to external impact. Using unclean containers or low‑quality hydraulic oil during refueling further accelerates clogging, which in severe cases can lead to pipeline rupture and oil leakage.
The oil pump is the "power core" of the lifting system, responsible for converting mechanical energy into hydraulic energy. If it fails and cannot supply oil, the entire lifting system will stop working completely.
Symptoms include: after activating the lifting switch, the carriage shows no movement; the pump makes no working sound, or emits harsh abnormal noise and overheating; oil leakage may also occur in some cases.
Causes include wear and seizure of internal parts such as gears and vanes, idling due to clogged oil inlet, leakage caused by aging or damaged seals. Long-term overloading and deteriorated hydraulic oil will also accelerate pump damage and shorten its service life.
Lifting switch blocked, control valve and return valve seized
This type of fault belongs to control component seizure, which directly affects the flow direction and pressure control of hydraulic oil, resulting in uncontrolled lifting.
Symptoms: the lifting switch does not respond or cannot reset when pressed; the carriage cannot lift or lower. When the control valve or return valve is seized, the lifting will be weak, lowering will be abnormal, and even excessive system pressure may damage components.
Causes are mostly dust and water entering the switch, lack of lubrication, impurities in hydraulic oil getting into the valve body and jamming the spool, wear and deformation of the valve body caused by long-term high-pressure operation, and failure to regularly clean and maintain the control components.
