Whether a trailer is pulling horses or a boat, the safety of the cargo inside depends on proper maintenance of the trailer's wheel bearings. Greasing the bearings must be done at regular intervals for proper load distribution and mechanical integrity of the wheels. Improperly maintained wheel bearings can cause wheels to detach without warning and result in damage to the trailer, its cargo, and perhaps people.
Wheel bearings are a critical part of the trailer body. They help support the trailer's weight and keep the wheels turning on the axle. Properly maintained bearings allow the wheel to spin freely, without putting unnecessary friction on the trailer axle. A wheel bearing that has been neglected eventually leaks and deteriorates. Dirt and other foreign objects can contaminate the bearings, cause breakdown of the assembly and possibly enable the wheel to detach from the axle.
Wheel bearing maintenance frequency depends on the trailer type, wheel size, and average load weight. Some manufacturers recommend inspecting and greasing an RV's wheel bearings once every season, or at least every 10,000 miles. But boat trailers with small wheels require repacking every 2,000 miles. Generally, the smaller the tire, the faster the wheels spin, which puts stress on the bearings. Frequency can also be determined by considering how the trailer is used and where it has travelled.
In 2008, the cost of having this job performed by a professional mechanic was approximately £81 per axle, based on average pricing obtained from three different RV repair shops in southern California. However, trailer owners who attempt this job at home will spend less than £65 in parts. The procedure calls for basic mechanical aptitude, and only requires high-temperature grease, rags, a trailer wheel jack, a torque wrench and a hammer. A bearing packer makes the job cleaner but is not necessary.
Wheel bearing design has remained unchanged over the last 50 years, and greasing them is simple. But before you attempt this at home, it is a good idea to have a service manual for your trailer with instructions for the procedure. The wheels must be properly torqued. Obtain a proper trailer jack, and block all tires on the opposite side to ensure your safety while underneath the trailer.
If your trailer has hauled excessively heavy loads or has been driven off-road or towed through water that covered the axles, it is a good idea to perform this maintenance. Also, some manufacturers forget to grease the wheel bearings prior to delivery to the dealer. To test new trailer wheel bearings for excessive friction, touch the tire after it has been in use. A hot tire surface could indicate improper lubrication.