What are the reasons for the forklift arm not lifting up?
3 Answers
Here are the reasons why the forklift arm cannot lift up: Internal leakage in the boom cylinder: During the use of the loader, hydraulic oil contamination or deterioration causes wear and aging of the seals inside the cylinder, resulting in ineffective sealing. This leads to internal pressure leakage in the system. Since the boom cylinder is an actuator, when internal leakage occurs, part of the system pressure is diverted back to the tank through the return oil pipe, causing the boom to fail to lift or to lift weakly. Internal leakage in the work pump or spline wear: The work pump pressurizes the system through the centrifugal force generated by the impeller rotating the hydraulic oil. When the gears inside the pump wear or oil leaks, the centrifugal force produced by the pump is insufficient to raise the system pressure to the standard value, resulting in low system pressure. Additionally, when the spline on the work pump shaft is severely worn, the spline slips, reducing the rotational speed, which also leads to insufficient system pressure and the inability to lift the boom. Insufficient hydraulic oil: When the hydraulic oil in the tank is insufficient, a large amount of air is mixed into the oil being delivered to the work pump, causing the pump to run idle. This reduces the system pressure and, in severe cases, can damage the work pump. Therefore, insufficient hydraulic oil can also prevent the boom from lifting.
As a seasoned mechanic with over a decade of experience, I believe that when a forklift's boom fails to lift, it's most likely a hydraulic system issue. Common causes include a worn-out oil pump failing to supply sufficient pressure, or leaking hydraulic cylinders due to damaged seals, resulting in insufficient power. Inadequate or contaminated hydraulic oil clogging the pipes can also cause this – I once encountered a case where impurities in the oil completely blocked the filter. Electrical faults are equally frequent, such as burnt-out control switches or relays, or poor wire connections interrupting the current, rendering the boom immobile. Mechanical issues like jammed boom joints, insufficient lubrication, or rusted bearings could also be culprits. Regular maintenance is crucial: monitor oil levels, listen for abnormal pump noises, and address any unusual sounds immediately. Neglecting these can not only delay work but also damage other components, increasing repair costs. I recommend regular oil changes and filter cleaning – prevention is always better than cure.
As a long-time forklift operator, I've encountered quite a few situations where the boom wouldn't lift. The most common causes are improper operation or switch issues, like the lever not being pushed all the way or buttons getting stuck and malfunctioning—replacing the part usually fixes it. Low hydraulic fluid needs topping up promptly; oil cylinder leaks leave traces on the ground, so spotting them early allows for quick action. Overloading is another frequent issue, triggering the safety valve to lock automatically—just reduce the load and try again. A quick check of fluid levels, switches, and boom joint smoothness often helps; if not, report for repair rather than forcing it. Safety first to avoid accidents and work delays. During maintenance, remember to add lubricant—these machines are tough but need care.
