Little wheels?

[theageofthetra]

On a train up to Hertford today my train paralelled an intermodal freight from Finsbury park variously over taking each other for some time. I noticed that some of the container carriers had tiny wheels to presumably reduce the height to keep within our loading gauge. Had me wondering are these the smallest diameter wheels ever used on a scheduled train on a standard gauge British Railway ? The front pair of bogie wheels on a "King" were quite small but these looked smaller than those. Lets also not count Wickham trolleys or other works vehicles. Open floor for suggestions from the wise sages on here. Cheers.

 

[newbryford]

Although small wheels are good for loading gauge issues/larger containers, the problem with small wheels means smaller surfaces for braking. You can't fit large brake discs on a small-wheeled axles. Clasp brakes generate heat within the wheel - small wheels struggle to dissipate the heat.
Small wheels could also mean that there is less clearance for bearings - internal or external.

I remember seeing a prototype small wheeled container wagon at Procor in Wakefield in the mid 80's - it was generally unsuccessful due to the above issues with braking/heat.

Cheers,
Mick

 

[carriageline]

Also, as the wheels get smaller, you have the problem of them failing to activate track circuits

 

[jopsuk]

small wheels also creates problems with bearings- as they need to rotate many more times for the same distance, it is as if with respect to the bearing the speed is higher.

 

[Smudger105e]

The ride quality of a small wheel is not the same as for a larger wheel either, that's why push bikes tend to have larger wheels.

 

[jopsuk]

Indeed- that's why, though Moulton was adamant that smaller wheels could give a faster bike, he had to invent a clever compact suspension system- which then went on to be developed into the suspension for the Mini (which also had the problems of tiny wheels).

For drve wheels, smaller wheels ARE better for acceleration given the same gearbox/drive train, but that's just simple gearing ratios in action, and is why some of the speed record TGV sets over the years have had outsize drive wheels fitted (along with stiffened suspension and spoilers)

 

[1018509]

Small wheels not good.

I remember many years ago covering the east cabin at Northfields depot on the London Underground when a train with locked wheels and therefore on "skates" entered the depot. The road I was to put it on had a bend and as the "skates hit the bend. From the cabin I saw the middle of a six car tube train approaching the cabin sideways as I legged it out of the door.

Skate wheel diameter is about a foot I imagine flange to flange

Fortunately only minor damage to the train and a motor change was required. There was extensive track damage though.