PART ONE

INTRODUCTION

Getting Started

Steam engines led the industrial revolution; their introduction into industry changed the way goods are produced, and therefore subsequently the way in which human beings live. Some will say this is a pity, as life now has a far quicker pace than it did before the industrial revolution, but others feel that the advantages of mechanization far outweigh the many disadvantages that it brought with it. Of course generally the steam engine as a means of power has long been superseded by the use of oilbased fuels and even nuclear power. Even so, much of industry is still powered by steam except that these days it tends to be used in turbines rather than the old-fashioned reciprocating engine.

Basically machines operated by steam are simple: it is a case of boiling water, collecting the steam that is generated in the process, and putting it in a closed cylinder so that it will operate a piston. The trick in being successful is the manner in which the steam is allowed in and out of the cylinder, and there are many methods of doing this, some of which are extremely simple, others that can be quite complicated, the latter engines being developed in the endless search for greater efficiency by the engine designers. This book will only deal with comparatively simple mechanisms; nevertheless, anyone making one of them will build a working engine.

So how does a steam engine work? In this modern world we have electrically operated kettles that switch themselves off as soon as the water boils, but not so very long ago the kettle was boiled on a stove, and when it boiled it was taken off to make the tea, or for whatever purpose. If you forgot the kettle had been put on and left the room, you would come back and find the room absolutely full of vapour, usually referred to as steam, although in fact it is actually the steam condensing. No matter; what it actually is is the result of steam having been generated, but the remarkable thing is that it has completely filled the whole room from a quantity of about a half litre of water. Thus there has obviously been a vast temporary expansion in the quantity, although when it condenses it will return to more or less the original amount.

If instead of leaving the room, the person who put the kettle on remains and perhaps dozes off, they would have been awakened by the sound of the lid of the kettle bouncing up and down. What is happening is that some of the steam cannot escape quickly enough and is pushing the lid off as it expands; obviously then the expansion of the steam is g