Abstract: A piston and cylinder unit for a gyratory crusher including a cylinder having an upper piston carrying the crusher head and a lower piston dividing the interior of the cylinder into a hydraulic chamber and a gas chamber. The hydraulic chamber is selectively chargeable with hydraulic fluid to adjust the crushing gap between the crusher head and the bowl of the crusher, and the gas chamber is connected in communication with a pressure relief chamber within the lower piston to provide an accummulator within the unit accommodating the momentary displacement of the crusher head by noncrushable materials moving through the crushing gap during crushing operations.

Abstract: A hydraulic accumulator particularly useful in connection with gyratory crushers of the type in which the crusher head and shaft are hydraulically supported so that when the crusher head encounters uncrushable material such as "tramp iron" the crusher head can move down to pass the tramp iron, causing at least some of the hydraulic fluid supporting the crusher shaft to be ejected to a hydraulic accumulator. A plurality of gyrations of the crusher may occur before the tramp iron passes. The accumulator chamber which receives the hydraulic fluid ejected from beneath the crusher shaft contains a gas precharged elastic bladder. Hydraulic fluid is admitted to the accumulator chamber through a poppet valve built into the accumulator structure, which valve is normally spring biased to a closed position against its valve seat.