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Stationary motors & Hit and Miss motors

August 20, 2010

More stuff from that show in Palo Alto last month:

This saw is powered by a horizontal single cylinder motor with two big flywheels.  The motor is controlled by a simple “carb” that looks pretty much like a brass elbow fitting with a needle valve in it.  It will spin at constant speed all day, while the workers would feed wood into the saw blade.

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This little motor is a hit and miss type.  It also has a primitive carb (seen in the bottom right of the photo), but it is much more recognizable than the one in the photo above.  Automatic inlet valves were used for low cost and simplicity.  No inlet cam, follower, pushrod or rocker was needed.  These motors are controlled by bob weights that spin on a flywheel.  As the wheels spin faster, centrifugal force pushes the weights outward.  They eventually contact a lever that forces the exhaust valve to stay closed.  When the motor slows a bit, then the weights come in and the valve is allowed to open and close for a normal 4 stroke operation.  Depending on the load on the motor (or lack of a load), they can go anywhere from skipping zero to a dozen exhaust strokes.  With a light load, they just spin and spin, then occasionally open the exhaust, compress a fresh charge of air/fuel, then fire.  Then maybe 10 spins before it does it again.  The sound is almost hypnotizing.  CHUFF CHUFF CHUFF CHUFF CHUFF BANG CHUFF CHUFF CHUFF CHUFF CHUFF BANG

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But if you manually move that linkage and allow the exhaust valve to open and close with every 4th stroke, the motor will very quickly pick up speed!  It will force the flyweights out with such force that your hand will not be able to hold the exhaust linkage open for more than a few firing strokes.

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Hit or miss motors were used on farms 100 years ago for their simplicity.  They only needed water once a day, and used very little fuel.  They could be carried to where they were needed:  pumping water at the well, spinning a saw in the barn, lifting grain at a conveyor, etc.

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This one was on an old cart.  The tank at the top of the crankcase holds water to cool the motor.  That WICO magneto is a bit different.  It doesn’t rotate, just oscillates back and forth.  As long as the armature is setup correctly, it will make a strong spark with each time it passes through the maximum flux area of the magnet.  These mags are rare now, and worth as much as the rest of the motor.  At swap meets it is common to see a large number of motors for sale, all of them without a magneto…

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Nice Lunkenheimer oiler above the water tank.

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Anybody recognize this little two cylinder motor?  They used to be commonly used in residential applications…

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Yep, it is from a Maytag clothes washing machine.  These little motors sputtered while they spun and oscillated dirty shirts, freeing up the woman of the house to allow her to do other things.

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