any bearing specialists out here ?

£18 here

May be easier to buy cheap and replace. Problem is the seal is to keep grease in, not water out, RO used to make water protected axles for boat trailers, twin seals, grease in water out, these days we don't make proper equipment.

Brian
 
I would not use sealed bearings but ensure the is a grease nipple so the bearings can be greased after dunking.

That how I deal with the bearings on my mobo trailer that I can tow for 800Km when I take the boat home.
 
simonfraser said:
i use 309609 wheel bearings for a launching trailer, they get dunked into salt water and are rinsed after

checking on line i can buy these for between 30 - 90 £ a bearing

what kind of specification do i need to look out for to extend the life of these ?
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Have you searched for the bearings in stainless steel? You would have a fighting chance with those, and a good grease plus a good wash-down, if unsealed.

Richard
 
At £34.99 for two from ebay its hardly worth worrying about corrosion, is it? Just replace them every two or three years?
Even at £25 each Simply Bearings' product will probably be better quality and still hardly costly.
 
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RichardS said:
Have you searched for the bearings in stainless steel? You would have a fighting chance with those, and a good grease plus a good wash-down, if unsealed.

Richard
Click to expand...

I've been questioning my self about stainless steel ball bearings that get immersed in sea water.

The stainless steel is a high carbon stainless steel for the hardness needed for life of the rolling surfaces.

Stainless steel AISI 440C
Stainless steel bearings have a higher chromium content (up to 18%) that makes them superior to SAE 52100 in terms of corrosion resistance. They can function at temperatures as high as 250°C but are low in hardness and overall load-carrying capacity, in addition to having a higher production cost [3].

AISI 440C is a high-carbon stainless steel used in rolling-contact bearings (ball or roller bearings). It is broadly utilised in corrosive environments and in applications where corrosion resistance is more important than load capacity, such as in instrument ball bearings [4].



Bearing steel chemical composition [3]

ELEMENT
% WEIGHT
SAE 52100 (USA)AISI 440C (USA)
Carbon0.95 - 1.1%0.95 - 1.2%
Chromium1.3 - 1.6%16 - 18%
Silicon0.15 - 0.35%1% max
Manganese0.5% max1% max
Molybdenum0.08% max0.75% max
Phosphorous0.012% max0.04% max
Nickel0.25% max0.25% max
Sulphur0.25% max0.30% max


AISI 440C can be heat-treated and hardened up to 60 HRC. Its major disadvantage is its shorter fatigue life compared to SAE 52100. However, some applications integrate the properties of high fatigue and corrosion resistance by using chrome-coated bearings made of the standard SAE 52100 steel [4].

We know 316 is the go to stainless for corrosion resistance in the marine environment. 316 is quite a soft stainless not suitable for ball bearings.

I think we need Vyv to give us his metallurgical experience.

If this is a trailer is not used for high speed road towing plain bearings like vesconite may be better.

After all we use don't use ball bearings in our prop shaft
 
simonfraser said:
'If this is a trailer is not used for high speed road towing plain bearings like vesconite may be better'

not, launching and recovery only, max speed is about 5 mph, distance 200 meters
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I would forget the ball bearings and fit some plain bearings may be from vesconite of PTFE.

Vesconite Design and Technical - designing your bushes ensures optimal life

You may be able to sweet talk then into sending you a sample.

Vesconite Standard Size 3D Printer Bushings - Vesconite

Or 3D printed bushes to match size/replace the ball bearings.
 
316 ball bearings are available, they are used in cryogenic pump duties, but their fatigue life would be somewhat limited for a trailer unless the load was light.
400 series martensitic s/s has quite good corrosion resistance and better fatigue life than 316. For relatively short journeys and frequent immersion I think they would be a good bet, but of course fresh water washing would help a lot.
Carbon steel bearings can corrode badly in one day without fresh water washing.
Not immersing them when warm is good advice to reduce ingress through the seals.
 
Boater Sam said:
How about hardwood bearings? Easy to turn. Something like lignum Vitae from old crown green bowls or greenheart.
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Interesting point - the (huge) bearings in the wet bits of paper mills used to be made of lignum but they were made in sections so that the grain was radial to the load, not bored out of a piece.

For this application I would use plain bearings if available for the stub axles or else buy the very cheapest proper bearings available and change them frequently, or at least have them available to swap out if inspection shows it is necessary.

However, the bearings in the trailer for my 22' 1.25t sailing boat get dunked twice a year and trailed slowly for 300 metres each way and have been fine for that purpose for 5 years. They are full of grease but I will certainly remove and replace them if it is going much further up the road
 
simonfraser said:
these guys can certainly make a similar bearing
Vesconite Standard Size 3D Printer Bushings - Vesconite

the side loads are interesting too, the 309609 is pressed into the hub, and if it pops out of the hub the wheel falls off
what is the terminology used for this type of bearing fitting ?
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It's not unusual for bearings to be pressed on to drive shafts and for all that stops the entire shaft falling out is the tightness of the pressed bearing.

Richard
 
RichardS said:
It's not unusual for bearings to be pressed on to drive shafts and for all that stops the entire shaft falling out is the tightness of the pressed bearing.

Richard
Click to expand...
True, half shafts have always been that way, sometimes with a retainer pressed on afterwards.
But these double ball race bearings are used on front wheel drive shafts where the shaft is through the bearing and held with a nut on the end of the shaft. The bearing is carried in the upright and is retained with a large circlip .
I would have expected a retainer of some sort on a trailer where the wheel is subjected to side loading in both directions.
Perhaps it is designed for only launching but its a complicated and expensive bearing for such a light duty.
 
simonfraser said:
these guys can certainly make a similar bearing
Vesconite Standard Size 3D Printer Bushings - Vesconite

the side loads are interesting too, the 309609 is pressed into the hub, and if it pops out of the hub the wheel falls off
what is the terminology used for this type of bearing fitting ?
Click to expand...

This shows the normal uub design that can either have deep groove or angular contact ball bearings

exploded-drawing_0.jpg


The bearings are pressed into the hub from both sides and the stub axle located the inner race then help in place with the nut and thrust washer.

In your case the inner race will be held in the same way but the outer race will be held in with a locating ridge on the outer side and a possibly a circlip in the inner side of the hub

This has arrangement has an inner circlip and a bolt on outer cap

0901d196805ece49-1109-0050---17000-w_tcm_12-292195.png


If a plain bush bearing is used you would use 2 bushes like this

1598344314704.jpeg

With or without the split
 
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when I had a trailer it would get dunked most weekends over the summer in lovely grubby Solway sea water I never had to change them for at least 3 years, might have been 5 when i did.
I traveled 40 miles to site and got the boat fully rigged for launch whilst the bearings cooled. I would then pump them full of grease JUST before launch AND immediately afterwards to expel any water.
It worked for me.

Regards Clive
 
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