A Comprehensive Guide to Overhead Crane Lubrication System Maintenance: Oil Selection Criteria, Lubrication Intervals, and Troubleshooting Common Problems
Mechanical failures in the 40% overhead crane are directly related to poor lubrication—either the lubricant wasn’t applied when it should have been, the wrong type was used, or too much was injected through a single tube, causing the bearings to burn out. We see these situations all too often during our maintenance and repair work.
Selection of Lubricants and Greases for Various Organizations:Use L-CKD320 heavy-duty industrial gear oil for the hoisting mechanism reducer; use L-CKC220 medium-duty gear oil for the main and auxiliary travel reducers; use specialized wire rope grease (such as Great Wall Dewei) for the wire ropes; use No. 2 or No. 3 lithium-based grease for the bearings (select based on rotational speed and temperature).
Fueling Interval:Change the oil in the gearbox after the first 500 hours of operation, and then every 2,000 to 3,000 hours or every 6 months thereafter; apply grease to the steel wire rope every 15 days; and grease the bearing housings every 500 hours. Specific intervals should be adjusted based on frequency of use and environmental conditions.
Centralized Lubrication System:For workshops where multiple overhead cranes are managed centrally, we recommend installing a centralized lubrication system—a single lubrication station that supplies oil to multiple overhead cranes simultaneously via piping, automatically dispensing oil at set intervals and in precise quantities. The initial investment is approximately 20,000–50,000 per station, but this system prevents issues such as insufficient or excessive lubrication.
I. Selection of Lubricants and Greases for Various Organizations
Different components of an overhead crane have different lubricant requirements. The hoisting gearbox is subjected to heavy loads and shock loads, so L-CKD320 heavy-duty industrial gear oil (viscosity grade ISO VG320) is recommended. The travel gearboxes for the main and auxiliary hoists are subjected to relatively light loads; L-CKC220 medium-duty industrial gear oil is sufficient for these applications. Wire ropes must be lubricated with specialized wire rope grease; ordinary grease must not be used as a substitute—ordinary grease does not contain penetrants, so when applied, it merely forms a film on the surface, while the inner steel wires continue to rub against each other dry. For bearings in all mechanisms, we recommend lithium-based grease No. 2 (general-purpose) or No. 3 (high-temperature); for motor bearings, use high-temperature grease (dropping point ≥ 180°C).
III. Typical Failures Caused by Poor Lubrication
Pitting of gearbox gears—Insufficient oil viscosity or excessively long oil change intervals cause the contact stress on the gear surfaces to exceed the load-bearing capacity of the oil film, resulting in pitting on the gear surfaces. Bearing cage fracture—Lack of oil causes the bearing temperature to rise, leading to fatigue fracture of the cage material (brass or steel). Accelerated Wire Breakage in Steel Ropes — Insufficient lubrication of steel ropes increases friction between strands, leading to a rapid increase in the number of broken wires. Statistics show that these lubrication-related failures account for approximately 40% of all crane mechanical failures, and the vast majority are preventable—provided the correct oil is added at regular intervals. By ensuring the correct oil selection, adhering to oil change schedules, and conducting regular oil condition testing, lubrication-related failures can be reduced by more than 80%.
Frequently Asked Questions
Q: How often should oil be added to the various parts of an overhead crane?
A: Grease the overhead crane wheel bearings every 3 months, the drum bearings every 6 months, apply wire rope grease to the wire ropes every 15 days, and lubricate the open gears once a week. Check the oil level in the gear reducer’s oil tank every 6 months and change the oil once a year.
Q: Can different types of grease be mixed?
Answer: We do not recommend mixing them. Mixing lithium-based grease with calcium-based grease causes changes in consistency and a decline in performance. When changing grease types, you must thoroughly clean out the old grease before applying the new grease.
