member 32 which is mechanically fastened by bolts for example to the ends of the tie rods 19 as clearly shown in fig5 the two air springs 30 each have three stages each air spring is located between the header and a hinged plate member 44 pivotally attached to the fixed frame of the crusher the header also includes wheels 50 which move within the track 52 and support the tie rods 19 against downward pivoting movement the cyclical movement of the moving jaw moves the header back and forth in the track 52 the actual extent of movement is smaller than the length of the track however the track has been sized to accommodate the various operating positions of the moveable jaw which positions are controlled by the bite setting of the hydraulic cylinders as shown in fig5 each air spring 30 is connected to an air supply tank 40 the air springs are maintained within a desired pressure range and the air tank 40 basically increases the volume of pressurized air and modulates the operating pressure such that the cyclical movement of the moving jaw and the adjustable movement caused by the hydraulic cylinders will not produce wide variations in the operating pressure of the air springs in this way the tensioning force exerted by the air springs is within a desired range and is not unduly affected either by the particular bite set by the hydraulic cylinders nor the cyclical movement of the moveable jaw fortunately the air springs 30 are quite tolerant with respect to lateral misalignment and therefore the exact mounting structure of the.