Matthew Murray - Steam Engine Manufacture

Steam Engine Manufacture

Although the firm still served the textile industry, Murray began to consider how the design of steam engines could be improved. He wanted to make them simpler, lighter, and more compact. He also wanted the steam engine to be a self-contained unit that could readily be assembled on site with pre-determined accuracy. Many existing engines suffered from faulty assembly, which took much effort to correct. One problem that Murray faced was that James Pickard had already patented the crank and flywheel method of converting linear motion to circular motion. Murray ingeniously got round this difficulty by introducing a hypocycloidal gear. This consisted of a large fixed ring with internal teeth. Around the inside of this ring a smaller gear wheel, with half the outer one’s diameter, would roll driven by the piston rod of the steam engine, which was attached to the gear’s rim. As the piston rod moved backwards and forwards in a straight line, its linear motion would be converted into circular motion by the gear wheel. The gear wheel’s bearing was attached to a crank on the flywheel shaft. When he used the hypocycloidal gear he was able to build engines that were more compact and lightweight than previous ones. However, Murray ceased to use this type of motion as soon as Pickard’s patent expired.

In 1799 William Murdoch, who worked for the firm of Boulton and Watt, invented a new type of steam valve, called the D slide valve. This, in effect, slid backwards and forwards admitting steam to one end of the cylinder then the other. Matthew Murray improved the working of these valves by driving them with an eccentric gear attached to the rotating shaft of the engine.

Murray also patented an automatic damper that controlled the furnace draft depending on the boiler pressure, and he designed a mechanical hopper that automatically fed fuel to the firebox. Murray was the first to adopt the placing of the piston in a horizontal position in the steam engine. He expected very high standards of workmanship from his employees, and the result was that Fenton, Murray and Wood produced machinery of a very high precision. He designed a special planing machine for planing the faces of the slide valves. Apparently this machine was kept in a locked room, to which only certain employees were allowed access.