OT: Adjusting trailer wheel bearings (with AP Lockheed drums brakes)

Any trailer experts out there? Or anyone who can advise on how to ensure that that I tighten the crown nut on the wheel bearings of my trailer hubs correctly rather than excessively or insufficiently?

FWIW the brake drum supports a pair of roller bearings which seat on a tapered shaft. The whole lot is secured by a crown nut and split pin which tighten onto the tapered shaft.

I did tighten the crown nut until there was no detectable freeplay - hands rocking the drum at 6 and 12 o'clock - before fitting the split pin.

Is there any better way of doing this?

TIA

Richard

Reply to
Richard Savage
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With split pin type bearing retention the normal procedure is to tighten gently until all slack is gone and then back off until the first split pin hole becomes available. There should be a tiny bit of free play after doing this. If the nut is too tight the free play will disappear when the bearing gets hot and the bearing will wear out. The exact torque requirement will be specified by the manufacturer but if nothing is available I'd suggest doing them up to 15 ft lbs to seat everything fully, back off, hand tighten while rotating the wheel until all play is gone and then back off to the first split pin hole. Then check you can feel just a smidge of rock at the wheel rim.

Reply to
Dave Baker

ITYM castle or castellated nut not crown nut?

There will be a procedure where you either:

  1. Tighten to a specified torque (pre-load) and then slacken off by a specified angle, line up the nut with the hole in the shaft and then put your split pin in, or

  1. Tighten to a specified minimum torque and then carry-on tightening until the castle-nut is aligned with the hole (but no tighter than a specified maximum torque). If you can't line up between min and max torques then you need to add a washer (or change the thickness or your existing washer) to allow you to get a line-up between the min and max torques.

Either way you will need a torque wrench to do it properly. Do you know what manufacture your trailer hubs are? You really need to find out in order to get a punt on the torque and procedure.

Reply to
Dave Osborne

You did right. If in doubt back off 1 castellation as there will be expansion with heat.

Reply to
R

The way I've been taught is to initially overtighten the bearing to make sure the bearing surfaces are bedded properly into the hub. Then to slacken until there is perceptible play, and then undo until the next position the split pin hole is uncovered by the crown nut.

I also find it's best to fit the wheel, to give more leverage. But it's also important to take into account of any other suspension movement you might feel which might confuse the bearing free play.

Generally, the bearing shouldn't be pre-loaded, and ought to have free play, or they'll wear out much more quickly.

Reply to
Fredxx

well probably with a dial gauge, but the acceptable way is to tighten till there is just no play, and back off to the neat=rest place you can sun a split pin through the castellated nut.

Reply to
The Natural Philosopher

What size and weight of trailer is it? Do you know the origin of the hubs, other than the fact that they have Lockheed drum brakes?

I assume that they are *taper* roller bearings - an inner and outer with the thin ends of the tapers pointing towards each other - so that they can take both radial and axial loads? If so, as others have said, there should be a

*small* amount of free play when they're correctly adjusted. [Incidentally, I doubt whether the shaft is tapered - more likely to be stepped to take the two bearing sizes.]

If you know the origin, you may be able to get some adjusting instructions from the original manufacturer - but you won't go far wrong with what you've done.

FWIW, I've got a Bailey caravan with an Alko chassis, and two sets of instructions - one from Bailey and one from Alko - which are sufficiently different that they can't possibly both be right - so I just follow my nose!

Reply to
Roger Mills

Oh..and |I forgot to say, you arent going racing in this thing are you? I means you aren't expecting to race at 180mph 3mm from a crash barrier?

In which case, don't be prissy about free play.

You wont notice it till its like 1/4"..on a trailer :-)

Under load, the bearings tend to 'sit in the middle' anyway.Its only lateral loads under heavy cornering that will cause the play to actually do anything.

Reply to
The Natural Philosopher

Trailer bed is 8' x 4' and neatly accommodates 1t of topsoil!

Yes

If so, as others have said, there should be a

OK

I suspect that the OEM has gone to the great trailer park in the sky. In any event there are no markings of the hub. I only know the brake type from staring at my copy of 'The Complete Trailer Manual'.

What I have done in the past is take up all of the freeplay and then tighten to the next available hole to fit the split pin through the castle nut (sorry for the miss-naming of the nut). Clearly that final tightening is wrong.

I have plenty of torque wrenches but no hub details. 15ft/lb sounds a good figure to start from.

Thanks to all. I'll be re-assembling it later and checking the other side.

In the event of needing new bearings, not the case yet as they spin freely with no suggestions of dragging or pits, do I wave the hub at my friendly bearing supplier (who?) and ask for duplicates?

Richard

Reply to
Richard Savage

More or less, yes.

Bearings are standard sizes. Especially in utility vehicles built from parts bins.

Reply to
The Natural Philosopher

Have a look at

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which tells you how to measure/ID your bearings.

If you can find a manufacturer name and part number on the bearings, other manufacturers are likely to have equivalence tables to find the matching item from their range.

Reply to
Roger Mills

The majority of bearings have a code stamped into the edges of the races. Depending where you are in the UK any good independent belt and bearing supplier should be able to determine from the codes what they are

Reply to
R

More tanks to all.

Richard

Reply to
Richard Savage

Bearings are invariably standard sized items with a nominal o/d, i/d and width. The bits they fit on are generally made to fit them rather than the other way round as it's easier to make the other bits to suit than design your own custom bearings. They'll all have a part number etched on the rim so either just give your bearings or their part numbers to any bearing supplier and they'll be able to find a match.

I'd advise only going for top quality bearing suppliers like Timken or SKF because some of the cheap and cheerful made in Itchifanni or China bearings are not quite the real deal in terms of either material quality, heat treatment or tolerances.

Reply to
Dave Baker

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Dave Baker" saying something like:

Except Toyo. Superb, they are.

Reply to
Grimly Curmudgeon

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