A Jaw Crusher uses compressive force for breaking material. This mechanical pressure is achieved by the crusher's two jaws dies, one of which is stationary and the other is movable. These two vertical manganese jaw dies create a V-shaped cavity called the crushing chamber, where the top of the crushing chamber is larger than the bottom. Jaw Crushers are sized by the top opening of the crushing chamber. For example, a 32 x 54 Jaw Crusher measures 32" from jaw die to jaw die at the top opening or gape opening and 54” across the width of the two jaw dies.
The narrower bottom opening of the crushing chamber is used to size the discharge material. A toggle plate and tension rods hold the pitman tight near the bottom of the moving swing jaw. The toggle plate is designed to perform like a fuse and protect the crusher in the event that an uncrushable material enters the crushing chamber. As a rule, Jaw Crushers have a 6:1 or 8:1 ratio for crushing material. Still using the 32 x 54 Jaw Crusher example, the top size of the feed entering the crushing chamber has to follow the F80 rule that 80% of the top size feed material is smaller than the gape opening. Using the F80 rule with the 32 x 54 Jaw Crusher, the 32” gape opening equals a 26” top sized feed, and with the 6:1 ratio of reduction, the discharge setting would be around 4”.
Since the crushing of the material is not performed in one stroke of the eccentric shaft, massive weighted flywheels are attached to the eccentric shaft and powered by a motor. The flywheels transfer the inertia required to crush the material until it passes the discharge opening.
