Yard trailer bearings

[dgadee]

Thinking of building a yard trailer which would be used for launching and recovery. Friend says standard bearings wouldn't last and would cost a fortune to replace. He suggested making/buying solid bearings instead - there are but a few metres to the water. Would an industrial plastic do - nylon? Boat is 4.5 tons +, and I supposed trailer would be another ton.

 

[vyv_cox]

I suspect that nylon would extrude under load and it would swell in water. There are engineering plastics that might do the job but these are fairly expensive with some unknowns.

By far the best would be phosphor bronze, used for high loading and low sliding speeds. Don't know about availability in tubular form. Leaded bronze would be a good choice but not quite as good as the phosphor type.

Here's one - abbeyspuncast.co.uk.

 

[vyv_cox]

I tried a sample purchase from easymetals.co.uk. 2 inch OD, 1.5 inch bore, 8 inches total, £65. (Wasting time waiting for dinner after a hard day!)

 

[dgadee]

I tried a sample purchase from easymetals.co.uk. 2 inch OD, 1.5 inch bore, 8 inches total, £65. (Wasting time waiting for dinner after a hard day!)

Ha! Not wasting time in my view at all.

 

[Plum]

Ha! Not wasting time in my view at all.

and while you have it in pieces, fit stainless grease nipples, and drill the grease ducts if they do not already exist. Grease after every immersion.

Www.solocoastalsailing.co.uk

 

[lw395]

Our club RIBs have standard trailer bearings.
They are launched and recovered and towed a few hundred yards twice a week 9 months of the year.
Bearings get stripped and greased or replaced at end of season and maybe greased a couple of times a year.
No issues mid season, maybe a bit noisy by the end?
Use the best grease and the problem is not as bad as all that?

 

[dgadee]

Our club RIBs have standard trailer bearings.
They are launched and recovered and towed a few hundred yards twice a week 9 months of the year.
Bearings get stripped and greased or replaced at end of season and maybe greased a couple of times a year.
No issues mid season, maybe a bit noisy by the end?
Use the best grease and the problem is not as bad as all that?

Bearings for 7.5 tonne axles appear to be about £300 (per axle or wheel, I'm not sure).

 

[lw395]

Bearings for 7.5 tonne axles appear to be about £300 (per axle or wheel, I'm not sure).

You don't need a 7.5 tonne axle for a 5 ton boat + trailer load.
If you look at trailer bearings, say the LM67048, they are about 8 quid a pair, £16/axle.
The 90 million revs rating is only 2720lb per bearing radial, say 5t/axle, but if you only want 1 million revs from it, that goes up a lot. 10k lb/bearing.

You have a choice, buy cheap and replace more often, over-rate a lot and pay a lot when it needs replacing.
I think you need to allow some safety margin, say all the weight on two wheels, a fewbumps etc, but it's not like doing 100,000 motorway miles of potholes.
Find a cheap axle. In the old days, the front axle for an early Transit was favourite.
Look at the bearing spec from Timken, SKF or whatever. The low speed ratings of quite small bearings are tonnes.
You might want to up that a bit to Merc Sprinter or similar.

Then design your trolley such that a bearing failure is not a 'railway accident'. I.e. worst case, a wheel comes off, the whole thing sits on the ground rather than falling over?

At the end of the day, moving boats is never free, you have to swallow a few costs or pay the marina. Even my dinghies go through tyres, trolleys rust, wheels wear....

 

[AndrewL]

You might consider lignum vitae, a very hard, naturally oily wood, which does not rot.

 

[oldharry]

Definitely NOT nylon It absorbs water and swells, jamming the bearing. Ask anyone who used it on their rudder bearings! Also unlikely to take the weight, even if doesnt deform and extrude, it will wear very quickly with that weight. As suggested, metal to metal bearing, well greased. Simple bar steel stub axle welded on to the chassis, then a plain metal bearing hub held in place by a washer and pin (split or R pins both suitable for this). Keep it well greased!. You may need a spacer at the inner end to keep the tyre from fouling the chassis.

 

[dgadee]

You don't need a 7.5 tonne axle for a 5 ton boat + trailer load.

Ah, but that's what I have sitting out the back of the house. Plan is to use just one axle (it's a twin keeler) and move with a tractor.

 

[William_H]

I would use ordinary car type taper bearings. Cheap to replace but can actually be pretty rough and still usable provided you check that they have grease and are not rusted up. So frequent checks will mean bearings lasts a long time. ol'will

 

[Daydream believer]

My axle is reversible ( just unbolt one bracket & reverse the bar) so i can have either. plastic beach wheels or road wheels. But my trailer goes in & out of the water every 3-4 weeks & the ball race wheel bearings are perfectly OK. I wanted 2 options because in the winter we tow it 300 yds up the road to storage & plastic wheels might not like that.

My trailer is much lighter than yours as it is built for a 20 ft long Squib at 600Kg but you get the idea I am sure
I have done an article on how I built it for PBO with some ideas for trailer building, but I am not sure that they will publish it as I think the editor does not think trailers are of interest to readers

If you do want bearings that are plastic then google Oilon from Plastics on line. I have turned up several bearings in my workshop from it & it is cheap. You can buy Phosphor bronze bearings impregnated with oil called oilite bushes fairly cheap.
I would use plastic wheels & get the tyres foam filled