Steam trains

[koster]

What do you call the wheel system that you get on locomotives, where the three or so wheels are connected by rods?

[boxtops]

bogeys ?

[boxtops]

I think I'm right http://en.wikipedia.org/wiki/Bogie

[Buenchico]

Coupling rods:
http://en.wikipedia.o...locomotive_components

[HowardKennitby]

The connected group are called the driving wheels as far as I know. The loose wheels on the loco and carriages are referred to as bogies.

[Clanad]

Here in the U.S., the wheels connected by rods and driving the engine are simply called drivers, whereas the undriven (usually smaller diameter) wheels are called pilot trucks... it swivels and guides the engine around curves...

The biggest steam locomotive in the world was built for the Union Pacific Rail Co. and operated near where we live...It was called the Big Boy and weighed in at 1.5 million pounds... it was quite a sight for a little ranch kid...

http://www.youtube.com/watch?v=x8f9VFlNyDQ&feature=related

[Toureman]

You are correct boxtops, in theUSA they are called trucks.

[Jonathan-Joe]

A bogie on a locomotive has two (sometimes three) axles and is pivoted to the loco so it is free to rotate slightly on curves; the driving wheels axles do not usually have this freedom of movement, so do not form a bogie. In British usage, a single axle free to move is usually called a pony truck.
Many of various numbers and configurations of locomotive wheels are named
Steam - http://en.wikipedia.o...ive_axle_arrangements
Diesel / Electric -
http://en.wikipedia.o...ki/Whyte_notationhave name

[koster]

Thanks for all your answers!

But on a typical steam locomotive, the drivers and the pilot trucks are connected with connecting rods which you can see. On a diesel locomotive, no doubt the drivers and the pilot trucks must be connected somehow, but you don't see it. So those connecting rods are something typical of steam locomotives, but a connecting rod is just one component, I'm wondering if there's a name for that kind of system or technology, where the driver wheels and the driven wheels are connected by rods visible on the outside of the vehicle.

[Jonathan-Joe]

On a typical steam locomotive, only the driving wheels, rigidly attached to the frame, were connected by rods. Connecting to bogies / trucks would require articulated rods to cope with curves - this would be difficult to engineer as thee rods carry huge forces.
Connecting rods are rare on diesel and electric locomotives.
In the days of steam, rods connecting the pistons to driving wheels held rigidly in the frames was just about the only design used, so there was no need for a specific word to describe it.

[heathfield]

Lucky you. Clanad - my experience of a Big Boy was limited to once spending an afternoon clambering all over #4006 at the Transportation Museum in St Louis! (I was in seventh heaven, but my wife wasn't impressed). Nice video, too. Meantime, for the curious, here's a picture on an electric loco that actually used connected drivers...

http://en.wikipedia.org/wiki/File:PRR_DD1.jpg

[Clanad]

It is a cherished memory, heathfield. I remember seeing three of these monsters hooked together pulling an 80 car freight train over the pass between Cheyenne and Laramie, Wyoming. Pouring black smoke for miles.

It's amazing that all of those huge, heavy moving parts could be designed and put together and still travel in excess of 70 MPH...

[heathfield]

Three together? Now that's left me with an utterly mind-boggling picture!! And at the speeds those beauties could attain, with all their weight behind them, it's said they tended to straighten out curves in the tracks! Whooo!

[woofgang]

In England when horses and carts were in everyday use, a farm cart was called "a pair of trucks" Two wheels joined by a shaft was known as a truck!