Needle Roller Bearing Axleboxes

[baggo]

Right chaps, I've set up the experiment!

I've only got 10mm bore needle bearings to hand so I've used one of those. The 'axle' is a length of 10mm silver steel fastened onto the end of a small induction motor. The bearing is press fitted into a small length of bar to simulate an axlebox. Hanging off the 'axlebox' is a bag containing 16.5lbs of scrap metal! The bearing was given a light oiling before fitting.



Working on the assumption that this would be fitted to a 2.5" gauge 0-6-0 loco the weight of the loco would be 99lbs!
The motor runs at 1275rpm so assuming a wheel diameter of 3.375" this gives a loco speed of nearly 13mph, so every hour run will be equivalent to the loco having travelled 13 miles. In 24 hours it will have travelled the equivalent of about 310 miles!

I'll leave it running as long as possible or until something breaks ;D

John

[baggo]

Just a quick update before I go to the Pub!

The setup's been running for 7 hours now less a slight timeout when one of the motor bearings seized up! Inspection showed that the motor only had plain bearings with felt oil retainers and these were bone dry - it's an old motor of unknown origin. Quick squirt of oil and back in business.

The axle has now travelled the equivalent of about 90 miles non-stop and the only effect on it seems a very slight dulling of the surface which runs in the bearing. Still, it's early days yet. I'll leave it running overnight and check it again tomorrow.

[SteveW]

Guys,

Found my original post from 8/8/04 "Using Needle Bearings" by "stevew":

Yesterday I met someone advocating using needle bearings in place of ALL plain bearings on the grounds of cost, ease of use and life expectancy. The target application ranging from wheels through to crosshead and everywhere in between.

He showed me a catalogue for needle races down to 1/8" shaft. He used ER forty something material for the mating shaft and had this nitrided.

The only significant rule of thumb was to use caged needles for rotating and un-caged for reciprical applications.

What he said and what he was producing seemed to make a lot of sense. Thinking about it, you only want to make it once, not having to re-visit the bearings routinely seems to be a good idea.

The other thing he does is to drill down the shaft to a cross drilling to provide grease to the bearing surface. Add a simple grub screw in the end of the shaft and job done for life. Also, it occurs to me that pushing the grease in to the middle will push any crap out the way it came in.

[baggo]

Hi all,

The 'experiment' has been running for 69 hours now. Out of curiosity I checked the motor speed with a tacho as the figure written on the motor seemed a strange rpm. The tacho showed it to be 1440rpm which is what most induction motors run at. This means that the theoretical '2.5" gauge loco' is actually running at 14.6mph rather than the 13 mph given before.

After the 69 hours running the bearing/axle has done the equivalent of 1000miles non stop! The bearing surface of the axle has become a dull grey colour but I cannot detect any wear with the equipment that I have i.e. micrometer and digital caliper.



It would be interesting to repeat the test with some ground mild steel but I've only got 3/8" dia and no bearings of that size to hand.

Referring to the 4-8-4 loco I'm building which is fitted with the bearing/axle combination tested, the weight carried by the axle under test is at least double what the axle will carry in real life, probably nearer treble, so I'm pretty confident that the silver steel axles will be good for several thousand miles of running. It's unlikely that the loco will see anything like that mileage in my lifetime!

I'm not going to suggest that the above test 'proves' the suitability of silver steel for axle material but it's helped to boost my confidence in using it. With regard to Simplex, I think the approximate weight of the loco is 120lbs so each bearing/axle assembly will carry about 20lbs plus any loads imparted by the pistons etc. The bearings for Simplex will be 3/4" wide (twice that in the test) so I don't really see that there will be any problems. Incidentally, inaccurate quartering can exert enormous forces on bearings, far greater than they would experience under normal running.

John

[baggo]

A further update to the above. I decided to leave the test running for a further 160 hours which means the 'axle' has now travelled the equivalent of 3,400 miles

The surface of the axle has not altered noticeably from the 1000 mile point and any wear is still too small to measure. I'm not going to bother carrying on with the test as there doesn't really seem much point. I think the motor bearings will give out long before the axle fails

John

[ron]

John
Excellent experiment, very interesting result.
As a matter of interest, Reeves no longer supply ground MS for Simplex axles when I asked them recently.
Ron

[baggo]

Hi Ron,

I seem to remember that when I was after some GMS for another loco about a year ago I looked at Reeves and they no longer stocked it. I think I got it from GLR in the end.

John

[Jo]

I had wondered why Reeves ground steel looked so cheap! The fact that they no longer stock it would account for why its price has not gone through the roof like the rest of the stuff they (try to) sell.

Jo

[ron]

Jo
I recently got a price list of parts for Simplex from Blackgates, for most parts Reeves are nearly 50% dearer, OK Blackgates are a bit amateurish but for that difference worth waiting for.
Surprisingly they were exactly the same price for the boiler kit, although I see that's gone up considerably since I bought mine recently due to rising copper prices.
Ron

[John Lee]

RE: from printers. I've actually tried some of that John, (hating to pay the price of materials ). You do of course mean old dot matrix or even better the old office type line printers. It was from old line printers when they were disposing of them at work.. I got to them before the recycler did!

The problem comes when you try to machine the ends to locate the wheels. Whatever is inside (its not alumium but its some sort of funny soft alloy) I'm not sure I'd trust it for an axle. Visions of excessive camber come to mind. Weigh one up..its nothing like the weight of the equivalent steel. But its certainly a hard surface.

Unless what you scavenged was different...

John

[John Lee]

ron said:

Jo
I recently got a price list of parts for Simplex from Blackgates, for most parts Reeves are nearly 50% dearer, OK Blackgates are a bit amateurish but for that difference worth waiting for.
Surprisingly they were exactly the same price for the boiler kit, although I see that's gone up considerably since I bought mine recently due to rising copper prices.
Ron

Yes; but I see location is SW Scotland so I guess you are mail ordering. If you are local enough to go there they are a pleasure to deal with and not amateur at all. It's a saw while you wait job... 12.125 rather than 12 inch if you need it.

Just patience..the fact that they moved recently, got some more, newer, staff can't have helped.

[keithwallwork]

Hi List

I was just reading the posts on needle roller bearings. Not mentioned was the fact that hardened sleeves are available which overcome any wear problems although you have to reduce the shaft diameter slightly. Trouble is they cost as much as the bearings and not all sizes are available.

Keith

[paul]

Hi Keith, welcome to the forum. You've given this thread one heck of a bump!