The Woolf Valve Gear is used in connection with an engine to reverse its motion. It is arranged with one eccentric attached to the crank shaft the strap of which has a long arm cast on, to which the eccentric rod that moves the valve is attached. This arm is also supplied with a roller, which runs in a slot on a rocking head. This head is held in position by a box and is connected to the reverse lever by a rod. By throwing the reverse lever to either end of the quadrant, the position of the rocking head is so placed that the roller in the slide operates the eccentric strap, rod and valve, and the engine will run in the direction desired. By throwing the reverse lever to the opposite end of the quadrant, the position of the rocking head is so changed that it will reverse the motion of the valve, and the engine will run in the opposite direction.
Woolf Valve Gear.
The Quadrant being notched, the point of cut-off can be regulated with the reverse lever, according to the load; by placing it in the last notch in quadrant when full power of engine is required, or notching it up when doing light work, the same as with the link reverse gear.
GOVERNOR.
The Governor contains a valve so constructed and connected with the weighted balls that an increase of speed of the engine throws out the balls, which raises the arms attached to valve rod, thereby closing the valve and thus decreases the flow of steam through the governor valve and reduces the speed of engine until the governor balls are again in their true position. Now, when the speed decreases and the weighted balls rise above their true position, the valve opens, allows more steam to enter the cylinder and the speed of the engine increases until the engine is again running at its proper speed.
Gardner Governor.
Governors are used to regulate the quantity of steam required to run an engine at a uniform speed under variation of load, and to run properly they should be kept perfectly clean and free from the accumulation of gummy substances caused by using inferior oil, which has a tendency to interfere with the free and easy movement of the different parts.
Q. If you desire to run your engine faster or slower with the throttle valve wide open, how can it be done?