When the engine ran it heated the water. Cooling was accomplished by the water steaming off and removing heat from the engine.
When an engine ran under load for a period of time is was common for the water in the reservoir to boil. Replacement of lost water was needed from time to time. A danger of the water-cooled design was freezing in cold weather. Many engines were ruined by the forgetful operator neglecting to drain the water when the engine was not in use and the water freezing and breaking the cast iron engine pieces.
Water jacket repairs are common on many of the engines that exist today. These were simple engines compared to modern engine design. However, they incorporated some very clever designs in several areas, many times because the designer was attempting to circumvent infringing a patent for a particular part of the engine.
This is no more true that in the area of the governor. Governors were centrifugal, swinging arm, pivot arm, and many others. The actuator mechanism to govern speed was also varied depending on patents existing and the governor used. See, for example, U. Patents , from or , from However accomplished, the governor had one job - to control the speed of the engine. In modern engines, power output is controlled by throttling the flow of the fuel mixture through the carburetor by means of a butterfly valve; the only exception to this being in variable displacement engines.
On hit-and-miss engines, the governor holds the exhaust valve open whenever the engine is operating above its set speed, thus interrupting the Otto cycle firing mechanism. The intake valve on hit-and-miss engines has no actuator. It has a light spring that holds it closed until the engine is on the intake stroke. When the piston is on the intake stroke, a vacuum is created in the cylinder as the exhaust valve is closed. This vacuum causes the intake valve to open, which allows the fuel mixture from the mixer to enter.
Hit-and-miss engines were made in horsepowers from 1 through approximately These engines are slow speed and typically ran from revolutions per minute rpm for large horsepower engines to rpm for small horsepower engines. A Jaeger Trash Pump used for pumping dirty trashy water. This is an example of an integrated function of hit-and-miss engines i. They were used to power pumps for cultivation, saws for cutting wood, generators for electricity in rural areas, running farm equipment and many other stationary applications.
Some were mounted on cement mixers. These engines also ran some of the early washing machines. They were used as a labour-saving device on farms, and allowed the farmer to accomplish much more than he was previously able to do. The engine was typically belted to the device being powered by a wide flat belt, typically from 2 to 6 inches mm wide. The flat belt was driven by a pulley on the engine that attached either to a flywheel or to the crankshaft.
The pulley was specially made in that it was slightly tapered from each edge to the middle so that the middle of the pulley was a slightly larger diameter. This design kept the flat belt in the center of the pulley.
By the s, more-advanced types of engines were being designed and produced. Flywheel engines were extremely heavy for the power produced, ran at very slow speeds, required a lot of maintenance, and could not easily be incorporated into mobile applications. In the late s International Harvester already had the model M engine which was an enclosed version of a flywheel engine.
Their next step was the model LA which was a totally enclosed engine except for the valve system featuring self-lubrication oil in the crankcase , reliable spark plug ignition, faster-speed operation up to about RPM and most of all, light in weight compared to earlier generations. You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser. Why Hit and Miss Engines?
Travis McCoy Registered. Hello all, I'm sure this question has been asked before, and I don't want to upset anyone, just looking for facts or at least some opinions. Here goes: Why was the hit and miss governing system used? Was it purely to save fuel? Or was it because throttle butterfly mixers are more complicated to manufacture? Or both? Or some other reason? The fuel economy seems like an answer that is too simple.
My reasoning is because of the lack of power strokes, and because you shouldn't run a hit and miss to where it is firing every 4th, at least that is what I have been told. Hopefully this makes sense, just trying to bend your ears on this because I get asked why a lot when I explain how the engines work. Thank you all; I look forward to hearing your thoughts. Again, this is just a quest for answers; I don't want to upset anyone.
Odin Subscriber. Its because of carburetor technology at the time. The manufacturers knew how to make a carburetor that worked, but it only worked really well at one specific setting. You had to adjust it for any other setting. Later on carburetor technology improved to where we could throttle the charge without messing it up too much, and the throttle governed engines began to win out for their better speed regulation and the ability to have multiple cylinders.
Jamesk In Memory Of. SBcasenut Hit-miss engines were quite fuel efficient , because when they were coasting with the exhaust valve held open they weren't using any fuel.
Having said that, if you put enough load on the engine it well fire every time, and by setting the spring tension on the gov. It worked quite well for the time. BobRR Registered. They are made to fire when needed including firing every time. They are a variable Hp engine, depends on the load.
They only make their rated HP. When firing every time Rated rpm. Say your running a buzz saw it will fire every time while cutting but will coast in between cuts saving fuel and helping the engine run a little cooler. Don Tomlinson Subscriber. In addition to saving fuel when coasting, the hit-and miss engines were also using no battery. The early engines were dependent on dry cell batteries for spark, which had to be discarded and replaced, so by not firing between power strokes the savings on batteries was important.
Later on the use of generators and magnetos eliminated the reliance on batteries for those that trusted them, but some still relied on the old, faithful dry cell battery. BMiller Registered. Also the water issue. A hit and miss engine cools between power strokes, and takes much longer to empty the water hopper. I ran an Associated throttler at shows, and had to add water to the hopper every few hours. A hit and miss engine will go much longer between fillings. Rich Mueller Sr Subscriber. Some probably had to do with metallurgy advances and higher speeds, after WW1, and the more abundant supply of gasoline in the 20,s after WW1, then the depression hit and WW2.
Also the advent of the light weight tractors, that could do many more jobs and very portable in the late 20,s , why buy a big heavy engine that was stationary , when you could get a small tractor with a belt pulley and drag stuff to or plow? The speed increased and hit and miss was not that feasible due to increased speed, valves floating etc. Don Tomlinson said:. Click to expand The Miss cycle: During the Miss cycle the exhaust valve is help open by the governor latch rod held ageist a stop on the tappet rod.
This allows a free flow of air as the piston moves on the down stroke. No suction is created in the cylinder so the intake valve remains closed cutting off the flow of the fuel and air mixture provided by the carburetor. The design of the stop on the tappet rod ensures it remains latched on the governor latch rod during the upstroke as well so air in the cylinder free flows past the exhaust valve preventing compression. This allows the engine to "coast" during miss cycles with the extra heavy flywheels providing stored rotational energy to keep the engine spinning.
The Hit cycle: As the engine RPM slows the governor weights on the flywheel succumb to the control springs pull and pull the governor latch rod away from the stop on the exhaust tappet rod. This allows the tappet rod to contact the cam on the timing gear. Subsequently the exhaust valve closes. On the piston down stroke vacuum is created in the cylinder which allows atmospheric pressure to act on the intake valve to open it.
As the piston transitions to the upstroke the intake valve closes. Stored energy in the flywheel forces the piston up on the upstroke even as compression in the cylinder builds up. Just before the piston reaches the top of this compression stroke the ignition system releases an arc of electricity across an air gap located on the spark plug.
The ignited mixture burns causing a rapidly increasing pressure wave within the cylinder. This pressure presses down on the piston on the down stroke which is converted to rotational energy which is transferred into the flywheel and any load attached to it. If the engines RPM is not sufficient to activate the governor latch rod the engine will enter another Hit cycle. When the engines RPM is sufficient to activate the governor latch rod the engine the engine will transition into the Miss cycle so a steady and controlled engine RPM is maintained.
Hi n4zou, I watched the video and really didn't find any glaring fallacies. I think they just simplified it for the sake of time constraints. Your explanation is well done and covers the operation of a hit and miss engine very clearly.
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