This invention relates generally to jaw crusher wherein a movable jaw that cooperates with a stationary jaw is rockably fulcrumed on a toggle plate which in turn is fulcrumed on a toggle beam that is adjustable in opposite directions toward and from the stationary jaw.
A jaw crusher of the general type to which this invention relates is disclosed in U.S. Pat. No. 4,165,044, issued Aug. 21, 1979 to Batch. That patent has been assigned to an assignee common with the present invention and discloses a toggle beam and a transversely shiftable wedge at each end of the beam whereby the toggle beam is wedged downwardly into a position in the way slots of the crusher side walls and locked therein.
Another prior art example of this type of jaw crusher is shown in U.S. Pat. No. 4,783,013, issued Nov. 8, 1988 to Polzin, and which also has been assigned to an assignee common with the present invention. That patent discloses shims behind a toggle beam which define various positions of its fore and aft adjustment along the way slots and in which the ends of the beam are guided.
Another example of the prior art is shown in the U.S. Pat. No. 4,927,089, issued May 22, 1990 to Joseph Altmayer. That patent discloses a pair of hydraulic cylinders or rams for controlling the movement of the movable jaw of a rock crusher between a first set position and a retracted position. That patent has means for simultaneously locking hydraulic fluid in first and second supply conduits to hold an extensible ram in a substantially rigid fixed length condition when in the set position during normal crushing operation. The ram 50 is mounted on one end to a non-adjustable fixed point on the main frame and the other end of the ram connects directly to the movable jaw. The length of the ram extension directly determines the location of the movable jaw.
U.S. Pat. No. 3,976,255, issued Aug. 24, 1976, to Edwards discloses a jaw crusher which utilizes a normal operating position between the jaws. The control system used in that patent is a timed action arrangement which utilizes an air/liquid intensifier for controlling liquid pressure within the cylinder by a supply and exhaust of air to and from the unit.
U.S. Pat. No. 4,637,562, issued Jan. 20, 1987 to Hagiwara et al., discloses hydraulic rams connected to the outlet portion of the breaker plate means and which operate independently of the breaker plate drive means to increase and decrease cyclically and incrementally the spacing between the lower ends of the breaker jaws. Still other examples of the prior art are shown in U.S. Pat. No. 5,799,888, issued Sep. 1, 1988; U.S. Pat. No. 5,765,769, issued Jun. 16, 1998; U.S. Pat. No. 5,769,334, issued Jun. 23, 1998; and U.S. Pat. No. 5,857,630, issued Jan. 12, 1999.
The present invention provides an eccentric jaw crusher for rock material and the like having a rigidly guided sliding toggle beam and a toggle for being hydraulically urged against the movable jaw to relatively position the movable jaw with respect to a fixed jaw to thereby vary the crusher closed side setting.
More specifically, the present invention provides a parallel hydraulic circuit including one or more double-acting hydraulic rams which provide a reliable overload relief system when tramp iron or other uncrushable material is encountered in the crusher. There is also provided a mechanical fixed stop for the movable jaw to ensure closer control of the closed side setting. With this fixed stop, it is possible to permit the uncrushable object to pass through the crushing chamber, and then the movable jaw is automatically returned to the established closed side setting. The hydraulic circuit provided by the present invention includes direct mounted relief valves, one for each ram, which permit a quick dumping of the oil to vent to a lower pressure area.
The invention thus provides a hydraulically clamping of the toggle beam forward and holding the beam rigid until the clamping force is overcome, for instance, by uncrushable material. A relief force is then transferred from the movable jaw to the toggle and to the toggle beam, to the ram rod and oil in the ram, which will then open the relief valves to dump only enough oil to drop to the preset pressure. A pressure compensated pump supplies makeup oil to restore the ram to its original position.
Another aspect of the invention relates to a crusher of the above type in which the toggle beam can be powered back by hydraulic rams to allow for quick closed side setting changes. The beam can also be powered back to allow for quick crushing chamber clearing of material due to unscheduled stoppage.
The toggle tensioning system provided is accomplished through a hydraulic ram and associated accumulator which is only powered to provide an easily adjustable constant tension force on the toggle and toggle seats. Tension must be maintained to keep the toggle in place between the seats due to the large amount of movement required when the crusher clears an uncrushable object. The movement is greater than a spring will handle effectively.
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