[modeleng] Re: Needle roller bearings

I got the bearings for Helen from RS components who stock a good range 
but, as mentioned by Ron, Arc Euro have quite a good range as well. I 
got the 3/4" bore ones for the Simplex from them and these are fitted 
with twin seals. Unfortunately, so far as I can tell, the type with 
seals don't seem to be available in the smaller sizes. On Helen I just 
put an O ring either side of the bearing. The two rear axles under the 
firebox are actually the fully enclosed cannon type to keep any ash etc 
out of the bearings and these have a screw in the middle of the 'tube' 
which can be removed to add a few drops of oil now and again. All four 
bogie axles are similar.

One way that some builders get around the oiling problem is to drill the 
ends of the axles and then put a cross drilling in the axle where it 
runs inside the bearing. Oil can then be squirted into the axle ends and 
into the bearings. You would have to be careful though to avoid dirt and 
grit being pumped in with the oil.

I believe that the amount of oil actually needed is minimal e.g. just a 
drop now and again. I have read that over oiling the rollers can lead to 
rapid failure of the bearing due to extreme pressures building up inside 
the bearing shell?Perhaps not true for the low rotational speeds for 
which we are using them.

John

Clif Walker wrote:
> Hi Ron and All,
>
> I have often thought about fitting needle rollers but where do you obtain 
> the actual needle rollers?
>
> Regards
>
> Clif
>   
>> I have fitted drawn cup needle roller bearings to all the axles of my
>> 2½" 4-8-4 Helen Long. The bearings run straight onto silver steel axles
>> and the usual side play is allowed so the axle can float from side to
>> side. I don't think you will have any wear problems - the axles and
>> bearings will outlast the rest of the loco! Most of todays loco
>> designers use this combination.
>>
>> There was some discussion about needle roller bearings on another forum
>> and some members seemed concerned about the life of plain silver steel
>> axles. As a result of this I conducted an experiment using a 10mm bore
>> bearing running on a silver steel axle as fitted to Helen. I connected
>> the axle to a motor running at 1440rpm and hung a 16.5 pound weight on
>> the bearing to simulate the load. This was the equivalent of a 2½" 0-6-0
>> loco weighing 99 pounds - a much greater loading than in real life
>> (Helen weighs about 45 pounds). The 'axle' was left running for a total
>> of 230 hours which in Helen's case would have equaled a distance
>> travelled of 3,400 miles! After this, there was no measureable wear on
>> the axle at all, only a slightly matt finish to the bearing surface. You
>> can see the experiment here:
>>
>> http://www.baggo.copperstream.co.uk/me/locos/25inch/helen%20longish/helen19.htm.
>>
>> I intend to fit needle rollers to my Simplex axles which are 3/4"
>> diameter and will again be silver steel.
>>
>> John
>>
>> Ron Head wrote:
>>     
>>> Hi chaps
>>> Does anyone have experience of fitting needle roller bearings to 
>>> locomotive axles, that they would like to share?
>>>
>>> I want to fit drawn cup sealed needle roller bearings to a 5" gauge 
>>> battery driven diesel shunter.  Ideally, I'd like to fit hardened sleeves 
>>> to the axles, but there isn't space to do this.  However, the axles are 
>>> of silver steel.
>>>
>>> The loco has six wheels, and so the middle axle will need to have some 
>>> side play.  If the axle is allowed to float through the bearing, there 
>>> will be sliding instead of rolling contact between the rollers and the 
>>> axle, and I wonder if there might be a problem with wear on the axle?
>>>
>>> Would it be better to constrain the bearing on the axle in some way, and 
>>> allow the axlebox to move in the horns?
>>>
>>> Over to you guys!
>>>
>>> Regards
>>> Ron
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