How to Extend the Life of Your Slewing Ring Bearings

 How to Extend the Life of Your Slewing Ring Bearings

Premature failure is a common fate for large-diameter (e.g., 8″ to 10′) bearings in heavy-duty applications where rotations are frequent. In big rotating equipment, such as cranes, excavators and tunnel boring machines, a slewing ring bearing must simultaneously handle a complex load spectrum that covers diverse combinations of thrust, radial and tilting moment loading.Get more news about Swing Bearing,you can vist our website!

Fortunately, there’s an easy way to protect your investment in these custom-engineered bearings. It’s called regular maintenance, and it can prevent 96% of slewing ring bearing failures. To maximize bearing life, simply follow these four tips – raceway and gear lubrication, torque checks on bolts, and seal inspection – and be alert for four warning signs of potential bearing problems.
A bearing should be lubricated at regular intervals with heavy-duty, extreme-pressure grease. Apply a liberal shot to the fittings around the bearing’s circumference at the interval recommended in the operator’s manual.

Slowly-rotating equipment or oscillating applications (e.g., backhoes, excavators, cranes) should be re-lubricated about every 100 hours of operation. More frequent lubrication – every day or even every eight hours – may be needed on equipment that moves rapidly or rotates continuously, such as trenchers and boring machines.

While adding grease, the bearings should be rotated to spread the grease throughout. Pump it in until you see the old grease squeeze past the seal; this is called purging. Purged grease carries contaminants out of the bearing. Rub some between your thumb and forefinger… if you feel grit or metal chips, you may have a bearing problem.

Grease tends to dry out over long periods of time, allowing condensation to form within a bearing. You can avoid this by introducing grease at least every six months, even when the equipment is sitting idle.

Gear Lubrication
Most large bearings have gear teeth that require lubrication, and those requirements are different than they are for the bearing itself. Since the meshing action of the teeth tends to squeeze out lubricant, gears should be lubricated every eight hours on slow-rotating or intermittently rotating equipment, and more often on rapidly or continuously rotating equipment. Small amounts of grease should be introduced at the point of mesh between the gear and pinion.

Seals
The seals on the bearing should be visually inspected periodically to be sure they are intact. Many people overlook the importance of seals, but they aid considerably in preventing bearing raceway contamination.

Bolts
A torque check on bolts should be part of any routine maintenance procedure. The frequency of these checks depends on the severity of service. Vibration and shock tend to loosen bolts, but periodic torque checks and tightening will help maintain the proper preload level.

Mounting bolts should be torqued to the proper level and checked periodically to ensure proper pre-tension. Improperly pre-tensioned bolts can fail, causing damage to equipment and, even more importantly, injuries to workers.

Bolt creep is another factor that should be monitored. Tightened bolts tend to creep or elongate over a period of time, reducing preload. Elevated temperatures can also increase bolt creep, so take this into consideration when developing a torque-check schedule.