Jaw crusher with a hydraulic cylinder overload arrangement

Quarried material is often processed by means of crushing plant, for the production of aggregate, for example. There are various known forms of crushing plant for the comminution of rock material and the like, one of which is referred to as ajaw crusher.One conventional jaw crusher consists of a frame having side walls and a pair of jaws, a fixed jaw and a swing jaw, disposed therebetween. The fixed jaw and a swing jaw each have a crushing face, the crushing faces being arranged in a spacedapart relationship to define a crushing chamber for receiving material to be crushed. The swing jaw is movable between a first position in which the crushing face of the swing jaw is inclined to the crushing face of the fixed jaw, and a second positionin which the crushing face of the swing jaw is brought substantially parallel to the crushing face of the fixed jaw, at a predetermined spacing therefrom.
The upper end of the swing jaw is connected to an eccentric shaft, which is located in a rotatable bearing. In use, as the bearing is rotated, the shaft is caused to proscribe a circle, which in turn causes the upper end of the swing jaw toproscribe a circle in the direction of the fixed jaw. Hence, the crushing face of the swing jaw moves in a crush cycle between the first and second positions, up and down, as well as towards and away from the crushing face of the fixed jaw. Movement ofthe swing jaw in this manner causes impelling forces for crushing material present in the crushing chamber.
Typically, a jaw crusher as described above will include a toggle plate located behind the swing jaw, adjacent the lower end of the swing jaw, for supporting the lower end of the swing jaw during the crush cycle. In a known type of jaw crusher,one end of the toggle plate reacts against the rear face of the swing jaw, and the other end of the toggle plate reacts against a cross beam provided behind the swing jaw and extending between the side walls of the jaw crusher frame.To enable a predetermined maximum product size to be produced during the crush cycle, the spacing between the pair of jaws at their lower ends, i.e. where the crushed material is discharged during the crush cycle, can be adjusted. It is known toinsert or remove shim packs or other adjustment means between the toggle plate and the cross beam, thus reducing or increasing the distance between the lower ends of the two jaws. It will be understood that larger pieces of crushed material are producedusing a greater jaw spacing than would be produced by using a smaller jaw spacing.