Tri-ang Thrust Bearing diameter

[Rana Temporia]

Following a repair to a DMU I realised that I don’t have any spare thrust bearings left. I have the brass bearing holders, oil retaking pads and the clips but that’s it. I have measured one with my cheap callipers and it shows 2.2mm but I would have expected them to be an imperial diameter. I know I can buy them off eBay but there is also a supplier of industrial bearings and I can have 1000 for the cost of four genuine ones. Does anyone know the correct nearest metric size? I am thinking of going for 2.1mm but wondered if anyone else has done this or has a more accurate (vernier?) set of callipers that they could measure one with?

[96RAF]

Find a twist drill that fits the hole and vernier up the drill, much easier than trying to measure IDs with a calliper.

[Rana Temporia]

Thanks for that suggestion 96RAF, it looks like the nearest is 2.2mm which is a good fit and I also found my 2.1 and 2.2mm bits were in the wrong parts of the drill box! The armature shaft diameter also measures at 2.2 with the callipers. I know it will be an imperial measurement but that looks to be pretty close and I drill my BA pilot holes with metric drills from a chart on the internet.

Looks like I may shortly have enough thrust bearings for several lifetimes of repairing Tri-ang motor bogies.

[Rana Temporia]

Unbelievably I was looking for something else and found a spec for the motor bogie which says the shaft is 3/32” diameter which works out at 2.381mm and is a standard ball bearing size so presumably that’s what Tri-ang used? It’d be interesting to see if the Kitmaster bogie used the same size as it apparently wasn’t a direct copy of the Tri-ang one??????? Looks like my callipers are slightly out by 0.18mm which I can live with at £2.99 with a spare battery for the measurements I need to do.

It looks like 2.2mm ones are standard in a number of camera mechanisms.

[96RAF]

My digi-callipers have a metric-imperial switch, but show decimal “ not fractions so you still have to do the math.

At work I dealt with bearings all the time and had several manufs CDs with their ranges as well a cross-ref charts from make to make. My bearings were a tad larger than loco motor ones at up to dinner plate outer diam.

[Rog RJ]

There are digital calipers available that can display fractional values.

Example https://uk.banggood.com/DANIU-150mm-Stainless-Steel-LCD-Screen-Display-Digital-Caliper-6-Inch-Fraction-or-MM-or-Inch-High-Prec-p-1373616.html?

[Rana Temporia]

For information and an update. I received the bearings this morning and the 3/32” seem to fit perfectly so I now have a bag of 50 which should be more than I will ever need, although I do have a few motor bogies that are awaiting a full rebuild and I have no doubt that some of the bearings will magically evaporate off the tray I use. I could have bought 1000 for a couple of £ more but I will never need that many and thought it was a waste.