A large, flanged wheel on a steam locomotive that is physically connected to the main rods and side rods. The pistons drive these wheels directly to propel the engine forward. Their large diameter allows for higher top speeds, while smaller driving wheels provide greater tractive effort for pulling heavy freight.
The shop crew is dropping the rear driving wheel to re-profile the tire and check the crank pin.
Railroaders almost always just call them drivers. The wheel arrangement of a steam engine counts the drivers in the middle number.
Also heard as
- driver
Related terms
Steam locomotive
A railway locomotive powered by the expansion of steam in cylinders.
Trailing wheel
An unpowered wheel assembly located behind the driving wheels on a steam locomotive.
Hammer blow
The destructive vertical force exerted on rails by the unbalanced reciprocating parts of a steam locomotive's driving wheels.