Watt steam engine

At the end of the power stroke, the weight of the object being moved by the engine pulled the piston to the top of the cylinder as steam was introduced.

The result was the same cycle as Newcomen's design, but without any cooling of the power cylinder which was immediately ready for another stroke.

Watt's early engines were like the original Newcomen designs in that they used low-pressure steam, and all of the power was produced by atmospheric pressure.

When, in the early 1800s, other companies introduced high-pressure steam engines, Watt was reluctant to follow suit due to safety concerns.

These double-acting engines required the invention of the parallel motion, which allowed the piston rods of the individual cylinders to move in straight lines, keeping the piston true in the cylinder, while the walking beam end moved through an arc, somewhat analogous to a crosshead in later steam engines.

[3] The solution to draining deep mines was found by Thomas Newcomen who developed an "atmospheric" engine that also worked on the vacuum principle.

As the piston rose within the cylinder, drawn upward by a counterbalance, it drew in steam at atmospheric pressure.

Hence, the pump deep in the mine attached to opposite end of the beam via ropes and chains was driven.

Seventy-five Newcomen pumping engines were installed at mines in Britain, France, Holland, Sweden and Russia.

In 1763, James Watt was working as instrument maker at the University of Glasgow when he was assigned the job of repairing a model Newcomen engine and noted how inefficient it was.

This increased the efficiency of the engine, but also created a variable torque on the shaft which was undesirable for many applications, in particular pumping.

In 1775, Watt designed two large engines: one for the Bloomfield Colliery at Tipton, completed in March 1776, and one for John Wilkinson's ironworks at Broseley in Shropshire, which was at work the following month.

[8] Watt had tried unsuccessfully for several years to obtain an accurately bored cylinder for his steam engines, and was forced to use hammered iron, which was out of round and caused leakage past the piston.

[9] In 1774, John Wilkinson invented a boring machine in which the shaft that held the cutting tool was supported on both ends and extended through the cylinder, unlike the cantilevered borers then in use.

Boulton wrote in 1776 that "Mr. Wilkinson has bored us several cylinders almost without error; that of 50 inches diameter, which we have put up at Tipton, does not err on the thickness of an old shilling in any part".

[9] Boulton and Watt's practice was to help mine-owners and other customers to build engines, supplying men to erect them and some specialised parts.

However, their main profit from their patent was derived from charging a licence fee to the engine owners, based on the cost of the fuel they saved.

[11] An arrangement of valves could alternately admit low pressure steam to the cylinder and then connect with the condenser.

Additional benefits of the double acting engine were increased efficiency, higher speed (greater power) and more regular motion.

This was effective in engines that were used for pumping water, but the double action of the piston meant that it could push as well as pull.

[13] He adopted the epicyclic sun and planet gear system suggested by an employee William Murdoch, only later reverting, once the patent rights had expired, to the more familiar crank seen on most engines today.

[14] The main wheel attached to the crank was large and heavy, serving as a flywheel which, once set in motion, by its momentum maintained a constant power and smoothed the action of the alternating strokes.

To its rotating central shaft, belts and gears could be attached to drive a great variety of machinery.

The Henry Ford Museum in Dearborn, Michigan houses a replica of a 1788 Watt rotative engine.

The American industrialist Henry Ford commissioned the replica engine from the English manufacturer Charles Summerfield in 1932.

In the 1880s, Hathorn Davey and Co / Leeds produced a 1 hp / 125 rpm atmospheric engine with external condenser but without steam expansion.

In addition, solarthermal collectors, geothermal energy sources and biomass reactors produce heat in this temperature range.

The Expansion Engine uses water as working fluid which is simple, cheap, non-toxic, non-flammable and non-corrosive.