page_title: Hit-and-miss engine
section_title: Construction
hierarchical_section_title: Hit-and-miss engine / Construction
caption_attribution_description: English: A typical engine oiler. This is one made by Lunkenheimer.
context_page_description: A hit-and-miss engine or Hit 'N' Miss is a type of internal combustion engine that is controlled by a governor to only fire at a set speed. They are usually 4-stroke but 2-stroke versions were made. It was conceived in the late 19th century and produced by various companies from the 1890s through approximately the 1940s. The name comes from the speed control on these engines: they fire only when operating at or below a set speed, and cycle without firing when they exceed their set speed. This is as compared to the "throttle governed" method of speed control. The sound made when the engine is running without a load is a distinctive "Snort POP whoosh whoosh whoosh whoosh snort POP" as the engine fires and then coasts until the speed decreases and it fires again to maintain its average speed. The snorting is caused by atmospheric intake valve used on many of these engines.
  Many engine manufacturers made hit-and-miss engines during their peak use—from approximately 1910 through the early 1930s when more modern designs began to replace them. Some of the largest engine manufacturers were Stover, Hercules, International Harvester, John Deere, Maytag and Fairbanks Morse.
context_section_description: A hit-and-miss engine is a type of flywheel engine.  A flywheel engine is an engine that has a large flywheel or set of flywheels connected to the crankshaft. The flywheels maintain engine speed during engine cycles that do not produce driving mechanical forces. The flywheels store energy on the combustion stroke and supply the stored energy to the mechanical load on the other three strokes of the piston. When these engines were designed, technology was less advanced and manufacturers made all parts very large. A typical 6 horsepower (4.5 kW) engine weighs approximately 1000 pounds (454 kg). Typically, the material for all significant engine parts was cast iron. Small functional pieces were made of steel and machined to tolerance.
  The fuel system of a hit-and-miss engine consists of a fuel tank, fuel line, check valve and fuel mixer. The fuel tank most typically holds gasoline but many users started the engines with gasoline and then switched to a cheaper fuel, such as kerosene or diesel.  The fuel line connects the fuel tank to the mixer. Along the fuel line, a check valve keeps the fuel from running back to the tank between combustion strokes. The mixer creates the correct fuel-air mixture by means of a needle valve attached to a weighted or spring-loaded piston usually in conjunction with an oil-damped dashpot.
  Mixer operation is simple, it contains only one moving part, that being the needle valve. While there are exceptions, a mixer doesn't store fuel in a bowl of any kind. Fuel is simply fed to the mixer, where due to the effect of Bernoulli's principle, it is self-metered in the venturi created below the weighted piston by the action of the attached needle valve, the method used to this day in the SU carburetor.
  Sparks to ignite the fuel mixture are created by either a spark plug or a device called an ignitor. When a spark plug is used, the spark was generated by either a magneto or else a trembler (or 'buzz') coil. A buzz coil uses battery power to generate a continuous series of high voltage pulses that are fed to the spark plug. For igniter ignition, either a battery and coil is used or a "low tension" magneto is used. With battery and coil ignition, a battery is wired in series with a wire coil and the igniter contacts. When the contacts of the ignitor are closed (the contacts reside inside the combustion chamber), electricity flows through the circuit. When the contacts are opened by the timing mechanism, a spark is generated across the contacts, which ignite the mixture. When a low tension magneto (really a low-voltage high-current generator) is used, the output of the magneto is fed directly to the igniter points and the spark is generated as with a battery and coil.
  
  Except for very large examples, lubrication was almost always manual. Main crankshaft bearings and the connecting rod bearing on the crankshaft generally has a grease cup—a small container (cup) filled with grease and a screwed-on cover. 
   When the cover is screwed down tighter, grease is forced out of the bottom of the cup and into the bearing. Some early engines have just a hole in the bearing casting cap where an operator squirts lubricating oil while the engine is running. The piston is lubricated by a drip oiler that continuously feeds drips of oil onto the piston. The excess oil from the piston runs out of the cylinder onto the engine and eventually onto the ground. The drip oiler can be adjusted to drip faster or slower depending on the need for lubrication, dictated by how hard the engine is working.  The rest of the moving engine components were all lubricated by oil that the engine operator had to apply periodically while the engine was running.
  Virtually all hit-and-miss engines are of the "open crank" style, that is, there is no enclosed crankcase. The crankshaft, connecting rod, camshaft, gears, governor, etc. are all completely exposed and can be viewed in operation when the engine is running. This makes for a messy environment as oil and sometimes grease are thrown from the engine as well as oil running onto the ground. Another 
caption: A typical engine oiler. 
  This is one made by Lunkenheimer
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