Hi guys,
Here is the photo of my CAD drawing that shows the hubs I am going to build for my L/S.
The axle where the bearings are mounted is 17mm dia. The end of the axle on the right hand side is 22mm in dia. The 17mm sounds rather small but the steel used is 4130 or 4140. These are very high strength steels and will handle any load (or crash) applied to it. The threaded end is M14-1.5 or M14-1 if I can find such a fine threaded nut. The nut/s that holds the bearings together are ajusted to give the minimum load that will keep the bearings together and still spin freely. A solid washer fits between the bearing and the nut/s.
The bearings are Angular Contact Bearings, 7203 - 17 x 40 x 12 with an angular contact of 40 degrees. The seal at the end is a Waveseal type CRWA1. The "wiper" on the RHS of the seal does not quite touch the shaft. Its job is to keep the dirt and crud away from the inner part of the seal. Waveseals display more than 20% less drag than other seals and their shape continually pulls the oil into the hub (but not the dirt). The lip of the Waveseal traces a sine wave path around the shaft. It does not run in a set position like other seals.
The hub is made from a machining grade of aluminium alloy and to cut down on the mass (weight) I will remove the thickened center part (but leave the shoulders of course). The method of fitting the hub to the wheel is not shown. This will be done by machining a flange on the end, above the seal, and it will be 5mm wide and about 6 or 8mm high. This locates the face of the steel wheel. The opposite end will have a similar flange but it will be threaded to tighten onto the other face of the wheel. To keep it all together, the assembled hub and wheel will be held fast with loctite.
Lubrication will be a light oil, probably auto transmission oil or lighter if I can find one that will serve the purpose. The oil level will be no higher than the bottom of the shaft or even half that amount.
A 22mm axle is very solid and heavy, this will be lightened by drilling a 12mm dia. hole into the 22mm dia. end up to the begining of the seal. The 17mm section is left solid. If I cant buy the caps for the LHS, I will have to make them from aluminium. The OD dia. of the housing as drawn/designed is 52mm (2 inches). This should, I hope, explain what I am doing. Your comments are welcome.

Kody

Hi Landyacht,
Thanks for the info. I altered the CAD drawing to have an open bore and a bush fitted in-between the bearings. I am at a loss to see how the outer housing can stay assembled with no shoulders to locate it. It is possible for the housing (the 52mm dia. part) to work its way off. I can still use a nyloc nut to ajust the bearing clearance and if the outer bearing is a sliding fit, the load on the bearings is equalized.
If the Waveseal proves to be a source of drag, I can swap the seal for a new style, eg. a typical knife edge, and ajust the shaft to suit. When the drawing is printed out to full size, the entire assembly is quite small. To rely on the tight fit of a bearing to secure the hub, is, IMO, very risky.

Kody

Hello Paul
Thanks for your interest in the design of my hubs. In regard to your question about the shoulder within the housing. If the two bearings are removed from the hub in the photo I posted, there is then a "step" or "shoulder" left as a solid part of the housing. These two shoulders form the seats that the bearings are located with. The bearings are pushed into the housing until they stop at the seat or shoulder. The outer shell of the bearing can be a push fit into the housing or even a "tight" fit. When the inner bearing raceways are fitted on the axle, they will slide along the axle to provide perfect alignment and a specific preload on the bearings. With the bearings located against the step or shoulder, it is impossible for the hub to come off the axle.
If there is no step or shoulder to provide positive location by having only a bush to separate the bearings and locate them, the hub can easily come off the axle. Without a step or shoulder, only the tightness of the bearings in the hub is going to hold the assembly together. After a very short while the risk of a breakdown (read - disintegration) from wear and tear becomes very high indeed. Should the hub part from the axle at high speed it could result in a tradgedy.
If such an occurance happened, the designer and builder of the (defective) hub would be totaly liable for damages and responsible for the loss of life involved.
I hope I have understood your post correctly and what you are asking, please forgive me if I haven't.
As soon as I find a suitable wheel (in Rockhampton) I will make up a complete assembly of the hub, run tests on it and take lots of photos for you all. I will even post photos showing how I made the hub, step by step.

Kody

Yes, Deep Groove gearings do provide a "shoulder" for the ball to seat in. The shoulder is actually the sides of the groove, if I understand your post and what you are asking. The inside edges of the bearing are the areas/parts that have to be located within the wheel. I can understand how a bush can help suport the bearings in a plastic wheel and this method will work but it's not highly efficient.
The hub/bearing assembly I am making is possibly very different to what most of what you all have, or have seen. The proof of the design can only be achieved by seeing it in action. I hope to leave you all still sitting at the starting line one day.
Having read so many posts about bearings siezing, falling out, rusting up etc. I decided to design a specific hub/bearing assembly that would virtualy last forever with a minimum of maintenance and still provide as little friction as possible.
As an engineer and designer, I have a vast amount of knowledge and experience in rotating assemblies and bearings and seals. The only drawback I have in regard to high speed and wining races is my weight at 135kg. 'nough said.
We must never forget that the bottom line in all stuff about landsailers is summed up very simply, - To enjoy your friends while you have them and have fun.

Kody

Now I understand. leave the shoulder there and have a bush between the bearing centres, then when you tighten it the bearings are aligned ,free rolling, and true.
Given you weight advantage I recommend going up to bearing with a 25mm shaft.
Also, when you build the yacht work out a system where you can get your weight well forward when starting off or sailing upwind and move backwards so that your backside is about 100mm forward of the rear axle when sailing downwind or at speed.
I have found thet even the heavier pilots still have thier bodywieght centred the same as the guys who get blown off the beach in 5knts. . get a plank and a wooden block and lay on it and find your balance point and use this in your design