DOUBLE ACTING SLIDE VALVE MODEL STEAM ENGINE

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DOUBLE ACTING SLIDE VALVE MODEL STEAM MILL ENGINE. 0.5" bore; 0.625" stroke, single cylinder double acting slide valve engine with reversing gear. The basic slide valve (of which t are many variations) is the most common of all fully articulated stationary and boat steam engine valve gear designs, the piston valve designs being most often associated with rail locomotives. This small model engine represents the range of "Mill" engines that powered factories throughout the Industrial Revolution, some of which still operate today, even if they no longer form the main motive power for workshops and factories. Many operated flawlessly powering factories for over a hundred years! The design is slightly unusual for small scale model steam engines, most of which are of the oscillating valve design, w the entire cylinder is allowed to oscillate, the oscillation of the cylinder forming the valve action. But the oscillating valve action is of necessity very simple, and does not allow for the more sophisticated steam overlaps and cut-offs that increase the efficiency of slide and cylinder valve double acting steam engines. This engine measures about 4 3/4 inches long overall, about 3 inches wide overall, and 3 inches high overall. It weighs 14 ounces. The construction of most of the main components is from aluminum, the base, upright, cylinder and steam chest. The 2 inch diameter flywheel, cylinder cap, crosshead guide, reversing slide, reversing lever, eccentric, crank wheel and crankshaft are from steel, while the piston, piston rod, connecting rod, valve connecting rod, eccentric arm and slider, the slide valve parts, slide valve plate, steam chest cover and steam inlet and exhaust connections are machined from 360 half hard brass. The use of aluminum for ther large parts accounts for the light weight. The engine was made from a commercially available kit comprising a set of drawings, a construction manual and most of the necessary metals and materials to allow the purchaser to machine all the parts and assemble the engine. I have not specified the manufacturer, since I was not entirely happy with the quaintly written and somewhat incomplete "Manual", the frequent advice to purchase some or other machine tool, from dividing heads at several hundred dollars to tiny specialized taps and dies one each of which would set the purchaser back another $70! This sum was almost the initial price of the kit! Needless to say, I made do with what I had, and modified the design w necessary to avoid the use of specialized and, to my mind, unnecessary purchases. I was unhappy with having to deviate so much from the written instructions and substitute my own methods and experience. Nevertheless, the finished engine after several problem solving head scratchings and deviations from the official instructions, turned out to be a pretty little engine that ran very well. This little engine will run on pressures as low as 8 p.s.i. and very satisfactory operation can be had at 25-30 p.s.i. pressure. As the video link below will show, the engine has so little friction it will even run on mouth pressure! My mouth pressure, too, and I am 80 and cannot blow so hard as some politicians can today! It has never been run on steam, all testing has been done using compressed air. The engine would be quite suitable to run on steam, but arrangement must be made for an in-line oiler if steam is used, and for safety a proper boiler with water level indication, a pressure gauge and safety valve is imperative. External oiling of the bearings and valve gear should be done before each operation on steam - I use ordinary 30 weight motor oil. If you wish to see an 8 minute video of this engine, which also shows it running under compressed air (and my mouth pressure!) then please follow this link: /watch?v=iYVOVWZeBVY read more

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