When it comes to hubs and bearings all trailers in Australia are pretty much the same. One can use 4,5 or 6 stud hubs with bearings sitting on a spindle and a couple of different electric brakes or if one dares even a hydraulic brake. However with hydraulic brakes the callipers and mounting brackets are rather limited and primitive for trailers.

I have been looking at some trailer parts and was questioning some of the play a bush had over a bolt and was told that this would be the best I can expect, it is “just” a trailer part. This was really irritating because I do not want to have play in a bush, it will develop eventually but it should not be there from the beginning. One would expect a bit more precision.

A main part of trailer maintenance is to make sure that the wheel bearings are packed properly and the wheel does not have any play but is running freely. Water ingress in bearings, over heating and running dry are all too common problems with trailer bearings.

One other consideration defined the way I have designed the running gear and that was the requirement to be able to use the same wheels on the trailer as on the vehicle. This was a little bit of a challenge in the beginning, because the wheel is an 8 stud dually wheel with 143mm offset. The other factor was the price of the components in the US compared to the very basic trailer parts here. An 8 stud hub with bearings running in a sealed oil bath, maintenance free with ABS sensor is a lot cheaper in the US than the cheapest hub here for the same weight rating. Having seen that the solution was obvious. Use the same components on the trailer as my truck has for its front wheels including the steering knuckles which has the required mounts for the calliper brackets. I did cut off a couple of bits from the steering knuckle which are not needed, had an adapter plate made, which can be welded onto an axle sleeve. One simple custom part and the problem was solved. Identical parts to the truck all the way and by far better quality components than any trailer part, and this included performance disc brakes with ABS sensors.

In the US an electric over hydraulic actuator with an ABS controller was readily available, which complemented the design of the running gear. I only had to use the same hub extensions for the hubs as my truck and I can mount the dually wheel on the trailer, saving me to take two extra spares.

Combined with an airbag suspension this is the most solid and reliable solution I can imagine for this weight class. Having a trailer with ABS is more important for a hydraulic system than an electrical system because it is more likely to lock up the wheels with its higher pressure (1600 psi). Without locking up the wheels a trailer is far less likely to break out and jacknife when braked hard, not to say it will not break out at all. ABS in the tow vehicle and ABS in the trailer keeps the combination steerable even under maximum brake force; a huge advantage over any other system.

The rating of the hub and brakes makes it possible to also run my suspension in non load sharing configuration. The wheel centres are below 1000mm apart, are considered close coupled, and can run without load sharing if each wheel pare can handle 120% of the required axle load as part of the GTM.