Posted by Clint Dixon on Friday, January 25, 2002 at 5:22PM :
In Reply to: Mechanical Engine Governor-- What was the original function? posted by J-Gilly on Friday, January 25, 2002 at 4:42PM :
The Power Wagon was designed, in part, to be used as a portable power plant. The optional Rear PTO setup terminated in the center of the rear crossmember. Mounted within the rear crossmember was a pillow block which had a 1-3/8" diameter splined male stub shaft extending rearward. This stub was like those found on common tractors of the time period. (Some tractors had stub sizes other than 1-3/8" diameter.) With a rear PTO setup of this type, and through the use of a PTO drive shaft to transmit power to equipment, the Power Wagon could power virtually any of the same agricultural or industrial equipment that a tractor could. An additional option for the Power-Wagon was a flat belt drive pulley that mounted onto the back end of the pillow block. It had a female spline that mated to the male spline of the pillow block. This pulley was designed to drive a wide flat belt used to power various equipment designed to be powered from a flat belt rather than a drive shaft. Flat belt driven equipment was in the process of being phased out of production when the Power-Wagon was first offered on the market. (One reason the belt pulley is more scarce that the rest of the rear PTO assembly.)
In both cases, a means needed to be provided to keep the engine speed (and speed of the driven equipment) operating at a continuous RPM as loads were applied to and released from the driven equipment. A common example is of a Power-Wagon being used to power a buzz saw. As wood is fed into the teeth of the saw blade, a load is applied to the engine and the engine will slow in reaction unless a means is provided to speed it up. As the teeth of the blade cut on throught the wood, the load is released from the engine and the engine's speed will increase.
This is where the Mechanical Engine Governor enters the picture. It is driven from an additional pulley and v-belt mounted between the radiator fan and water pump. Through centrifugal force, it reacts to an increase in engine speed and closes the carburetor's throttle plate through the movement of linkages. In effect slowing the engine back down. It also reacts to a reduction in engine speed by opening the throttle plate. Speeding the engine back up again. Adjusted correctly, the governor and engine will find a happy medium together which will keep the engines speed at a reasonably steady rate as loads are applied and released. The governor had an adjustable means to control initial engine speed over a range needed to power various equipment.
The main benefit of a governed engine used in powering equipment is an extended life expectancy of both the engine and equipment. Without it, the saw teeth could be moving way too fast as they contacted the load, or the engine RPMs could be pulled down far enough as the load increased to cause the engine to lug, or both!
Clint
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