Trailer bearings

  'Mallard' stays on a purpose built trailer in the barn during the winter months while I work on her and then come the spring I tow her back to the marina for the coming summer. As trailers go it is a substantial affair and capable of many miles but even though the trailer only does a couple of hundred miles each year total I am careful to take care of it. One of the things that I am most nervous about is one of the  wheels coming off at high speed and me coming to a grinding halt, or worse. To allay those nightmares I take time each year to service the wheel bearings carefully.

It is important that the bearing and grease are in good condition especially if you regularly dunk the trailer axles into the sea. Rinsing with fresh water as soon as possible will prolong the life of the trailer and prevent it from going rusty, but back to those bearings.

Jack up the trailer and check for rumble from the bearings as you rotate the wheel with your hand. Next grab the top and bottom of the wheel and try to rock it. If you hear noises from the wheel or there is more than an 1/8 th of play then the bearing may be in need of some TLC.

The photo above shows the dust cap removed and you can clearly see the castellated nut and cotter pin that holds the hub unit and bearings onto the stub axle. If when you remove the dust cap you find water or metal filings then further investigation is necessary and you should remove the hub and service the wheel bearings (I'll show how to do that in a later posting).

While it is more than possible to over pack a bearing with grease most failure are dues to over heating often caused by the rear bearing and seal failing and all the grease running out causing over heating and failure. In extreme cases of over heating the hub can literally weld itself to the axle which in turn is then sheared off by the force of the wheel still trying to turn. I've seen a couple of these and it is not pretty.

This is a cutaway through a typical trailer hub. The outboard end is at the top which in this case is fitted with a bearing buddy which in my opinion are worth their weight in gold as it is a simple matter to pump in some extra grease from a grease gun from time to time. the pressure from the gun tends to ensure that the grease reaches the rear bearing which as I mentioned above are the ones that tend to fail.

Here is a shot of the same hub in the first photo in which the dust cap which was removed for servicing has been replaced with a bearing buddy.

If you trail your boat please check your bearings periodically.

TIP
As an added safety check I put my hand on each of the hubs any time I stop for gas. If one is noticeably hotter than the others then this is sign that something is amiss.

Comments

[Wheel Bearings]

Thanks, very helpful on figuring out how my bearings work.