For light-duty cranes, oil is their lifeblood; however, severe oil leakage is currently a common issue with this type of equipment. Here, Qingdao Wanli Hoisting Machinery discusses the causes of oil leakage in crane gear reducers.
Let’s take a look at the issue of oil leakage in light-duty cranes!
I. Significant pressure differential between the inside and outside of the reducer: During operation, friction generates heat, and external ambient temperatures can cause the reducer's internal temperature to rise excessively. Without a vent or similar exhaust outlet, internal pressure builds up alongside the rising temperature, increasing the pressure differential relative to the outside environment; this pressure difference forces lubricating oil to leak out through gaps.
II. Unreasonable structural design of the reducer.
1) The inspection port cover plate is too thin; tightening the bolts can cause deformation, resulting in an uneven mating surface and oil leakage through the contact gaps.
2) During manufacturing, castings may not undergo aging or annealing treatments to relieve internal stress; this inevitably leads to deformation and the formation of gaps, resulting in leakage.
3) The absence of an oil return groove in the gearbox housing allows lubricating oil to accumulate at locations such as end caps, shaft seals, and mating surfaces; under the influence of the pressure differential, the oil leaks outward through the gaps.
4) Unreasonable shaft seal design. Early reducer models often utilized oil groove and felt ring seal structures, relying on the compression and deformation of the felt during assembly to seal the mating surface gaps. If the contact between the shaft journal and the seal is imperfect, the felt's poor compensation capability causes the seal to fail quickly. Although oil return holes are present in the oil grooves, they are prone to clogging, rendering the oil return function ineffective. III. Excessive oil fill: During the operation of the speed reducer, the oil in the reservoir is vigorously agitated, causing lubricant to splash throughout the unit. If the oil level is too high, large amounts of lubricant accumulate at points such as shaft seals and mating surfaces, leading to leakage.
IV. Improper maintenance procedures: Oil leakage can also result from inadequate cleaning of mating surfaces during equipment maintenance, the use of unsuitable sealant, incorrect installation orientation of seals, or failure to replace seals in a timely manner.
The issues described above are common occurrences during the operation of many cranes. Understanding the underlying causes allows for effective resolution, thereby ensuring smooth production and preventing financial losses for the enterprise.
