TECHNICAL FIELD The present invention relates generally to a hard rock crushing apparatus and particularly to a novel, portable, low head room or low profile crusher for primary reduction of ore or hard rock close to the active working areas in underground mining operations.

BACKGROUND ART Particularly as applied to underground mining operations, a reliable, efficient and low profile portable underground hard rock crusher has long been needed to improve underground ore handling systems. One of the pri¬ mary causes of low productivity in underground mines is the inefficient ore handling which is currently exper¬ ienced. Studies sponsored by the United States Bureau of

Mines (USBM) have documented the long-felt need for such a crushing apparatus which would make possible more effic¬ ient use of currently operated conveyor systems by bring¬ ing haulage closer to the face of the mine and eliminate expensive rock handling procedures. It has been estimated that as much as a 50% increase in productivity could be realized if primary reduction crushing apparatus could be employed at an earlier stage to permit smaller beltable material to be available close to the working site. Present crushing apparatus having the, required capa- - city for primary reduction application in this area are not easily transported and require too much head space for economical installation close to working areas to obtain optimum haulage from the face to the dump locations.

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Prior art hard rock crushers which are currently well-known in the industry and used in hard rock crushin applications, such as the gyratory, Blake type, overhead eccentric and cone crushers, all have relatively high profiles for comparable capacity ranges to be employed t appropriately solve the ore handling problems facing the industry.

It has also been noted in a government sponsored study, the Rapidex report under USBM Contract No. JO2850 that an eccentric jaw crusher with overhead feed is un¬ suitable and that apparent use of an eccentric jaw crush which has been turned on it's side for horizontal feed through the crushing chamber is not suitable due to the difficulty of conveying the material through the chamber and the need for a chain conveyor disposed near or adjace to the length of the crushing chamber.

Other types of prior crushing apparatus which are o low profile design are not suitable for hard rock appli¬ cations or do not possess the required size and through- put capacity for practical use in such applications.

According to the same study, a rotary type jaw crusher h been proposed to attempt to meet the needs mentioned abo However, as compared to the present invention, I believe that such a crusher has serious limitations in the con- text of the applications described above which will rend such a crusher less satisfactory than the present inven¬ tion.

SUMMARY OF INVENTION The present invention is characterized by its novel crushing jaw design which combines eccentric crushing action and a lower feed inlet in an efficient space-savi construction which provides comparable capacity in a muc lower head room design in a reliable, efficient rock crusher. This low profile is achieved by a novel arrang ment of the crushing jaws and the attendant arrangement

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of the remaining necessary components.

In the present invention, unlike prior art eccentric crushers, the crushing jaws are inclined to form an in¬ clined crushing chamber sloping downwardly from inlet to discharge with the lower jaw being movable to impart the crushing action between it and the stationary upper jaw.

.This arrangement of the jaws provides a powerful and most efficient crushing of material while maintaining very adequate feeding of the material through the crushing chamber.

Additionally, the arrangement of the crusher jaws in this manner permits the attendant eccentric shaft, drive means, and movable jaw support to be positioned in a lower profile manner on the frame as well as reduce the height at which the conveyor system feeds the inlet of crusher chamber to permit the feeding system to be mounted at a lower position on the frame.

It is a primary -object, therefore, to provide a port- able, low head room, hard rock crusher which has a dram- atically reduced profile compared to prior art apparatus suitable for use in underground mine applications, but which has a crushing chamber capacity comparably equal to prior art crushers which require significantly greater head room than required by apparatus constructed in accordance with the present invention.

It is another object of the present invention to provide an apparatus of the type described which may be more easily and efficiently transported from site to site compared to prior art hard rock crushers.

It is a further object of the present invention to provide an apparatus of the type described which includes the aforementioned features and yet is of comparable ease to manufacture and maintain relative to prior art hard rock crushers.

It is still another object of the present invention to provide an apparatus of the type described which may b advantageously utilized much closer to the working areas of underground mines for greatly improving ore handling and production in such mines.

It is another object of the present invention to provide an apparatus of the type described wherein the disposition of the moveable jaw and its associated eccen¬ tric drive means not only contributes ^' to the lower head room requirement but further assures efficient transport of the crushed material from the crushing chamber inlet t the discharge opening.

Further objects and advantages of the present will be apparent from the following description, referen- ces being had to the accompanying drawings wherein a preferre'd form of embodiment of the ^* invention is clearly shown.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of a portable hard rock, low profile crusher apparatus construction in accordance with the present invention and shown with associated" feed and discharge conveying systems;

Figure 2 is a partial side elevational view of the apparatus shown in Figure 1 illustrating the eccentric driven crushing jaw means and crushing chamber shown apar from the associated main frame and assessory equipment; and

Figure 3 is a top plan view of substantially that portion of the apparatus shown in Figure 2. DETAILED DESCRIPTION

A portable, low profile, hard rock crushing apparatu constructed in accordance with the present invention is illustrated in Figure 1 and includes a main frame, indi¬ cated generally at 20, which is supported_for movement by several pair of conventional wheel means such as at 22 and 24.

The crushing portion of the apparatus, indicated generally at 26, is centrally located on the frame ad¬ jacent to a conventional feed conveyor system 28 and above a discharge conveyor system 30. The feed and dis- charge conveyor system are of conventional nature and a variety of standard types could be employed within the context of the present invention. Further, a typical scalping mechanism is usually included to remove fine or the like prior to entry into the crushing chamber. An eccentrically mounted shaft means 32 is opera- tively connected to a pair of fly wheels, such as at 34, which in turn is driven via a belt drive 36 connected to a conventional motor 38. Each of these components may be mounted on the frame in any conventionally suitable manner.

Now referring specifically to Figures 2 and 3, the crushing apparatus 26 is shown in greater detail and in¬ cludes a stationary jaw means, indicated generally at 39, which includes supporting frame 40 mounted for pivoted movement at its upper end via a shaft 42, which in turn, is supported at each end to main frame 20 in a convention¬ al manner. A replaceable jaw liner 44 comprising a highly wear resistant material, such as manganese for example, is releasably fixed to supporting frame 40 by means of threaded wedge-like member 46.

The lower end of the stationary jaw means is releas¬ ably fixed in position by a toggle arrangement 48 provided with a series of shims 50 which may be easily used to ad¬ just the position of frame 40 pivoted about shaft 42 to vary the discharge opening between the jaws.

Toggle arrangement 48 is held in place by means of a plurality of rods 52 pivotally mounted to flanges, such as 54, carried by support 40 and provided with a threaded end 56 carrying a nut 58 extended through a suitable hole in main frame 20. By simple manipulation

of nuts 58 and shims 50, jaw means 39 may be pivoted and locked into a new position.

It should be pointed out that stationary jaw means is inclined relative to the horizontal, sloping downward fromthe feed inlet of the crushing chamber of the dis¬ charge outlet.

A moveable jaw means, indicated generally at 60, includes a supporting frame or pitman 62. The upper end of pitman 62 is supported by a toggle arrangement indica ed generally at 64, located beneath the feeder end. The upper and lower ends are attached to a tube-like support 66 provided with eccentric bearings 68 mounted on eccen¬ tric shaft 32.

A pair of main frame bearings 70 are mounted on the main frame and connected to shaft.32. Each end of shaft 32 is mounted to a fly wheel 34 provided with counter weights to offset the unbalanced weight of pitman 62.

One of fly wheels 34 is connected to a conventional electric motor 38 via belt drive 36 to provide rotary power to. shaft 32.

It should be pointed out that pitman 62 includes si plates 74 and the extended collar-like portion 76 which is connected to tube-like support 66 such that the eccen tric motion of shaft 32 is imparted to pitman 62 and the _. replaceable jaw liner 77 mounted thereon by a removable threaded wedge-like member 78.

It is desirable to provide detachable wear plates such as 80 to each of the side plates to pitman 62 in view of the abuse normally encountered in the crushing chamber during operation.

The moveable jaw means 60 is also disposed in an in clined position with the upper end adjacent to the feed inlet 82 of the crushing chamber 84 defined between the respective jaws and the pitman side plate's. The lower end of chamber 84 includes a discharge opening 85 for the processed material which falls to the discharge conveyor 30.

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- 1 - Toggle arrangement 64 includes an adjustable and replaceable toggle seat 65 mounted on a cross member 67 fixed to the main frame.

Another replaceable toggle set 69 is provided at the top end where.it is connected to pitman 62. It may be desirable- to provide for positive retention of toggle 64 in seat 69 by means of a releaseably mounted spring or the like to prevent inadvertent unseating of the toggle during adverse operating conditions. By adjustment of the position of toggle arrangement

64, the motion of the feed end of jaw means 60 may be varied according to the most desirable action for a given crush¬ ing application.

Further, both toggle arrangements 48 and 64 serve as a safety mechanism as they may be designed to break should uncrushable material enter chamber 84. Being easily re¬ placeable and relatively inexpensive, this provides a safety factor for preventing more serious damage to the other components which represent more difficult and expen- sive repair or replacement.

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