# How does steam train wheels work?

## How does steam train wheels work?

When heated, water turns to an invisible vapor known as steam. The volume of water expands as it turns to steam inside the boiler, creating a high pressure. The expansion of steam pushes the pistons that connect to the driving wheels that operate the locomotive.

## What do the numbers on a steam locomotive mean?

In this system numbers are assigned to the leading, driving, and trailing wheels of the locomotive. The first number is the number of leading wheels. The middle number (or numbers) give the number and arrangement of drivers. The last is the number of trailing wheels (typically under the firebox).

What do the numbers on the side of a train mean?

The numbers, in order, then represent the number of leading (unpowered), the number of drivers, and the trailing number of unpowered wheels. In your example, 2 leading wheels, 6 drivers, a second, independent set of 6 drivers, and 2 trailing wheels.

How does Walschaerts valve gear work?

When greater power is necessary, e.g. when gaining speed when pulling out of a station and when ascending a gradient, the Walschaerts valve gear enables the engine driver to set the cutoff point near the end of the stroke, so that the full pressure of the boiler is exerted on the piston for almost the entire stroke.

### What is a slide valve in a steam engine?

The slide valve is a rectilinear valve used to control the admission of steam into and emission of exhaust from the cylinder of a steam engine.

### What pressure do steam trains run at?

200-300 PSI
The essential action of any steam engine, stationary or mobile, is that of steam under pressure (200-300 PSI for most locomotives) entering a cylinder-piston assembly and pushing against the piston as it expands in an effort to reach normal atmospheric pressure.

How do locomotives get their numbers?

Why do locomotives have numbers?

Picture a locomotive with it’s front facing to your left. The numbers, in order, then represent the number of leading (unpowered), the number of drivers, and the trailing number of unpowered wheels. In your example, 2 leading wheels, 6 drivers, a second, independent set of 6 drivers, and 2 trailing wheels.