Roller type crushers are well known and generally comprise one or more rollers rotatable about their longitudinal axes and carrying a plurality of teeth which on rotation of the roller act on the mineral to break it up. The teeth are subject to very heavy wear, and are also liable to break in service, and therefore crushers frequently have their operation interrupted for teeth replacement. Alternatively, routine servicing of crushers is necessary, and this of course represents "down time" of a piece of equipment of substantial capital value, which is therefore being under utilised.

However, with existing equipment, the replacement of teeth can be a very laborious and time consuming exercise. In the case of crusher teeth provided as integral components of crusher rings, it is necessary to dismantle the crusher in order to slide a crusher ring (with worn or damaged teeth) off its shaft and to replace it with a new ring.

The present invention has therefore been developed with a view to facilitate the replacement of worn or damaged teeth without having to remove the roller shaft on which they are carried.

According to one aspect of the invention there is provided a rotary crusher comprising a plurality of toothed crusher rings mounted on a rotatable shaft having first and second ends, said crusher comprising a frame including (1) a first end in which the first end of the shaft is mounted for rotation and (2) a second end in which is mounted a stub shaft assembly for supporting the second end of the shaft, the stub shaft assembly being axially displacable

between a first position in which it supports the second end of the shaft and a second position in which it is spaced from the second end of the shaft to enable the crusher rings to be slid off the shaft without removal of the shaft from the crusher.

Preferably, the crusher shaft is mounted within a crusher frame having a drive coupling mounted thereon and coupled with said first end of the shaft which forms the driven end thereof, and so that the second end comprises the non-driven end.

In a preferred arrangement of rotary crusher, a pair of crusher shafts are mounted in the crusher frame parallel and adjacent to each other, and the shafts may be rotated so as to feed mineral to be crushed into the nip defined between the two rollers in order to effect a crushing action thereon. Alternatively, the shafts may be rotatable in opposite directions and each co-operates with respective breaker plates arranged on the opposite sides of the shafts to the nip therebetween.

The crusher rings are preferably provided with integrally formed teeth, and can therefore be cast robustly as one-piece castings. However, it is within the scope of the invention for the crusher rings to be provided with replaceable teeth, in which case replacement crusher rings may be provided with renewed teeth thereon, ready for replacement of a crusher ring with worn or damaged teeth.

The crusher rings may each be assembled from two or more ring segments which are coupled together, and in such a way as to be separable relatively easily when it is required to remove the rings. The coupling together of adjacent ring segments may comprise suitable releasable fasteners, such as bolted couplings.

Thus, rotary crushers according to said one aspect of the invention, and optionally with one or more of the preferred aspects thereof, can readily facilitate the replacement of worn or damaged crusher teeth without the

, the improved means of mounting the second end thereof via the axially displacable stub shaft assembly.

According to a further aspect of the invention there is provided a roller crusher for crushing mineral and the like material and comprising a roller formed of a plurality of crusher rings, each ring including one or more integral crusher teeth and including a central aperture bounded by at least one planar surface, said crusher rings being mounted on a rotatable shaft having at least one planar surface for co-operation with the planar surfaces of the rings to transmit rotational movement from the shaft to the rings.

By virtue of the co-operative surface formations of the rotatable shaft and of the central apertures of the crusher rings, it is readily possible to displace the crusher rings axially along the shaft during assembly or disassembly.

In a preferred embodiment of the further aspect of the invention, each crusher ring comprises two or more segments, and each segment carries at least one crusher tooth. The segments are adapted to be mounted around the shaft to form the crusher rings, and adjacent segments of each ring are releasably secured together.

In one preferred arrangement, the segments of each ring are bolted together and thus any segment can be readily removed merely by undoing the bolts. However, to facilitate separation of the ring segments, preferably the coupling arrangement is such that the bolts are exposed along at least part of their shanks so that the shanks can be cut through by means of a suitable torch to enable even more rapid replacement of a segment with broken or worn teeth. This arrangement will be particularly useful for cases in which the coupling bolts are rusted-in position, or otherwise secured fast in position.

A further preferred embodiment within the scope of the

further aspect of the invention provides crusher ring segments which are held together radially by being mechanically engaged with a pair of one piece spacer rings also mounted on the shaft either side of the crusher ring. In this case, by axially displacing the spacer rings with respect to a given crusher ring, segments of the crusher ring can be readily removed from the shaft and be replaced.

A still further embodiment within the scope of the further aspect of the invention provides crusher rings which are formed in one piece. In this case, when it is desired to replace one of the crusher rings, the rings between it and the. end of the shaft need to be removed by being axially slid along the shaft to provide access to the crusher ring to be replaced.

In the rotary crusher of the further aspect of the invention, the shaft includes at least one planar surface to engage with the corresponding planar surface(s) of the aperture of each crusher ring. Further, the shaft may, for example, be square in cross-sect ^' ion; have a circular section including two planar portions parallel to one another; or a circular section having a single planar portion.

According to another aspect of the invention there is provided a rotary crusher for crushing mineral and the like and comprising a roller formed of a plurality of crusher rings spaced apart along the axis of a rotatable shaft, in which each crusher ring comprises- two or more ring segments, and spacer rings are arranged one between each adjacent pair of crusher rings and engage with the ring segments of each crusher ring to maintain them in assembly as crusher rings around the shaft.

The spacer rings may engage the adjacent crusher ring assemblies in any convenient manner, to retain them against radial separation relative to the shaft. In one form, each spacer ring may have annular flanges projecting axially from each side of the ring and arranged to engage on

shoulder portions define on t e a acent crus er r ng segments so as to hold them captive against radial movement .

Alternatively, the annular flanges of the spacer rings may engage in annular channels defined in the adjacent crusher rings, again to retain them against radial displacement, though in this case both radially inwardly and outwardly.

Embodiments of rotary crusher according to the invention will now be described in detail, by way _. of example only, with reference to the accompanying drawings, in which:

Figure 1 is a top view of a first embodiment of roller crusher in accordance with the present invention;

Figure 2 is an end view of the crusher of Figure 1;

Figure 3 is a side view of one type of crusher ring for the crusher of Figures 1 and 2;

Figure 4 is a side view showing two forms of another type of a crusher ring for a crusher in accordance with the invention;

Figure 5 is a schematic vertical section through part of another embodiment of roller crusher in accordance with the invention;

Figure 6 is an end view of a part of the crusher of Figure 5;

Figure 7 is _§ a side view of the part of Figure 6;

Figure 8 is an end view of a further part of the crusher of Figure 5;

Figure 9 is a schematic vertical section through part of a further roller crusher in accordance with the invention; and,

Figure 10 is a schematic illustration of a still ^• further embodiment of roller crusher in accordance with the invention.

Referring now to Figures 1 and 2, the crusher includes a pair of rollers comprising a pair of square sectioned

rotatable shafts 1 and 2 mounted for rotation in bearings 3 in a box like frame 4. Shafts 1 and 2 rotate oppositely in the directions indicated by the arrows. The shafts 1 and 2 include meshing gears 5 and 6. Shaft 1 is driven by a motor (not shown) through reduction gearing (not shown). Shaft 2 is driven from shaft 1 via gears 5 and 6. Each shaft carries a plurality of crusher rings 9, each ring carrying a plurality of integral teeth 10. In use, shafts 1 and 2 rotate in opposite directions so that mineral pieces fed onto the rotating rollers are carried to the nip between the two rollers where they are broken down into smaller pieces. Alternatively, the rings can be mounted so that their teeth face in the opposite direction. In this case the directions of drum rotation are reversed so that the mineral is crushed between the teeth and breaker plates 7 secured to or pivotted from the side walls of the frame 4.

Referring now to Figure 3, there is shown a first embodiment of a crusher ring 9 for incorporation in the crusher of Figures 1 and 2. Each crusher ring 9 is formed of two generally semicircular segments 11, each of which is identical to the other and is formed of manganese steel. Each pair of segments together defines a crusher ring having a central square aperture. Each segment 11 carries a number of integrally formed teeth 10, and has a flange 12 at each end provided with a bore in registry with the corresponding bore in the flange of the other segment so that the segments may be fastened together by means of prestressed bolts 13 passing through the bores, and securing nuts 14. A plurality of crusher rings assembled in this way is mounted on the shafts 1, 2 and adjacent rings may be staggered through 90° so that the teeth 10 of one ring are not in registry with the teeth of the adjacent ring. The outer surface of the segments co-operate together to form the outer surface of the roller. Although one bolt only is shown at each end of each segment, it will

be appreciated that two or more o ts may e prov e a each end if desired.

During use of the roller crusher, damage to the teeth 10 is quite common and when it is desired to replace a segment carrying broken teeth, it is merely necessary to stop the roller crusher and undo the nuts 14 to enable the defective segment 11 to be removed for replacement by a new segment. The new segment is retained in position in exactly the same way as the old segment by passing bolts 13 through the co-operating bores in the flanges 12 and attaching the nuts 14.

It may be noted that the flange 12 of one of the segments is spaced from the corresponding flange 12 of the other • segment forming the crusher ring. Thus, a part of the shank 13a of each bolt 13 is exposed. In these circumstances, if desired, instead of undoing the nuts 14, the bolts may be removed rapidly merely by cutting through the exposed shank 13a by means of a suitable torch, and this arrangement will be especially useful when the bolts become "seized-up".

* Referring now to Figure 4, the top half of the figure illustrates a part of a one piece crushing ring 20 having a relatively few large teeth 21 integrally cast with the ring. The ring includes a central aperture which is generally circular in section but is provided with a pair of parallel flats 22 at opposite s.ides of the axis of rotation 23 of a shaft 24 on which the ring is mounted. The shaft 24 has a generally circular section including two planar surfaces so that it corresponds to the shape of the central aperture of the ring 20. The lower half of Figure 4 shows a generally similar one piece ring 30 carrying a relatively larger number of smaller teeth 31 integrally cast with the ring. The ring includes a central aperture of generally circular section except for a pair of parallel flats 32 located at opposite sides of the axis of rotation 23 of the shaft 24 on which the ring 20 is mounted.

Although, as shown, the crusher rings 20 and 30 are one piece rings, they could, if desired, be formed of two halves bolted together in a manner similar to that described in Figure 3 or otherwise held together about the shaft 24.

In use, rotational movement of the shaft 24 about axis 23 is transmitted to the rings 20, 30 as a consequence of the flats of the shaft 24 co-operating with the flats 22, 32 of the aperture. The teeth 21, 31 of the rotating rings then break down the mineral into smaller pieces dependent on tooth size.

Referring now to Figures 5 to 8 there is shown another form of roller crusher in accordance with the present invention. The crusher includes a rotatable shaft 40 having a generally circular cross-section but provided with two planar portions 41 parallel to one another at opposite sides of the axis of rotation 42 of the shaft. Mounted on the shaft is a plurality of integrally formed teeth 44. Each crusher ring 43 is in the form of a pair of semi¬ circular segments which together define a central aperture having a shape corresponding to the cross-section of the shaft 40. The segments of each crusher ring are provided, at each side, with a peripheral shoulder 45. Located between each pair of adjacent crusher rings 43 is a one piece spacer ring 46 which has a central aperture which may be circular or have a shape corresponding to the cross- section of the shaft 40. Each side of each spacer ring 46 is provided with a peripheral lip 47. The relative dispositions and dimensions of the shoulders 45 of the crusher rings 43 and the lips 47 of the spacer _. rings 46 are such that the lips 47 can rest on the shoulders 45 when the crusher rings 43 and the spacer rings 46 are adjacent to each other. The outer side of each of the end most crusher rings 43 is engaged by an end ring 48 carrying a peripheral lip 49. similar to the lips 47 of spacer rings 46, which engages with the adjacent shoulder 45 of the crusher ring.

In this way, the segments of the crusher rings 43 are held together by the spacer rings 46 and end rings 48 about the shaft 40.

Towards each end of the shaft 40 there is provided a groove 50 extending around the periphery (see Figures 6 and 7). The diameter of this groove is less than or equal to the distance between the planar portions 41 of the shaft 40 (see Figure 6). The crusher rings 43 and spacer rings 46 are axially located along the shaft 30 by means of a clamp ring 51 provided at each end of the assembly of crusher rings 43 and spacer rings 46. Each clamp ring 51 has a central aperture having a generally circular shape, but with planar surfaces 52 so that it corresponds to the cross-section of the shaft 40. Each ring 51 also includes an annular flange 61 having an inner diameter corresponding to the outer diameter of the shaft 40 to keep the shaft 40 and the ring 51 concentric in all positions. Each clamp ring 51 is slid onto the shaft 40 from its respective end until it reaches the groove 49 and it is then rotated with respect to the shaft 40 through about 90° so that the planar surfaces 52 of the aperture of the clamp ring 51 _. lie within the groove 49 and hence prevent the clamp ring 51 from moving axially with respect to the shaft 40. A plurality of holes 53 having internal threads is provided in the periphery of each clamp ring 51 and screws 54 are threaded into holes 53 so that their free ends bear.against the adjacent end ring 48. In this way, the assembly of crusher rings 43 and spacer rings 46 can be centralised on the shaft 40 and securely located axially with respect to the shaft.

In use, the shaft 40 of the roller crusher is rotated (by, for example, a drive mechanism similar to that shown in Figure 2) so that pieces of mineral fed onto the roller are broken down into smaller pieces as a result of the action of the teeth 44 of the crusher rings 43.

Referring now to Figure 9, parts corresponding to

parts of the previous figures are denoted by like reference numerals. In this embodiment, the shaft 40 also carries both toothed crushers rings 43' and spacer rings 46'. However each crusher ring 43' is composed of two similar halves with co-operate together to form a crusher ring having a central aperture having a shape corresponding to the cross-sec ion of the shaft 40. Likewise, each spacer ring 43' is composed of two similar halves which co-operate together to form a spacer ring having a central aperture having a shape corresponding to the shaft cross-section.

The halves of each crusher ring 43' are such that each has a periphery which includes a substantially full width part which is to be in registry with one of the planar portions of the shaft 40 and the halves of each spacer ring 46' are such that each has a periphery which includes a narrow part which is to be in registry with one of the part-circular portions of the shaft. Thus, the joining plane of the crusher ring halves is at 90° to the joining plane of the spacer ring halves. The nominal register between the spacer rings and the shaft is sufficient to ensure that the spacer rings rotate with the shaft.

Each crusher ring 43' includes an annular recess 61 at each side and each spacer ring 46' includes a spigot 62 at each side having a configuration corresponding to the configuration of the recess 61 of the adjacent crusher ring 43' .

The crusher rings 43' and spacer rings 46' are assembled on the shaft 40 so that the spigots 62 of the spacer rings 46' engage in the recesses 61 of the adjacent crusher rings 43' whereby the rings are locked onto the shaft. The rings are located axially with respect to the shaft by the clamp rings 51 and screws 54 as above described.

When it is desired to replace one of the rings, the screws 54 are removed to enable the adjacent rings to be moved axially away from the ring to be replaced thereby

disengaging the spigots and recesses holding the ring in position. The two halves of the ring can then be separated and replaced by new ring halves.

Referring now to Figure 10 of the drawings, the upper part of Figure 10 shows the crusher in its normal operating configuration and the lower half shows the crusher in a configuration enabling the removal of the crusher rings.

The crusher comprises a frame including a first end 101 , and a second end 102 and a drum shaft 103 rotatably mounted within the frame. The shaft may be of any desired cross-section. Thus, for example, it may be of circular section including an axially extending keyway, a square section, or a round section including one or more flat surfaces. Mounted on the drum shaft 103 is a plurality of crusher rings 104 each including a central aperture having a section corresponding to the cross-section of the drum shaft 103 and each carrying a plurality of teeth 105 on its outer periphery. Thus, rotation of the shaft 103 causes corresponding rotation of the crusher rings 104. Located between adjacent crusher rings 104 are spacer rings 106 which are provided so that there is a desired spacing between adjacent crusher rings.

The drum shaft 103 is driven at its first end 107 by means of a suitable motor and transmission (not shown) and its first end 107 is mounted for rotation in a suitable bearing arrangment in the first end 101 of the frame. Mounted in the second end 102 of the frame is a stub shaft assembly 108 shown cross-hatched for the purposes of clarity. The stub shaft assembly has a free end 109 which engages with a correspondingly shaped recess 110 in the second end 111 of the drum shaft 103. The assembly 108 also includes a flange 112 in which a plurality of clamp screws (not shown) are threadingly engaged so that the crusher rings 104 and spacer rings 106 can be axially secured between these clamp screws and a shoulder 113 provided on the drum shaft 3 at its first end 107. The stub

shaft assembly 108 is secured to the drum shaft 103 by means of a retaining bolt 114 covered by an end plate 115.

The stub shaft assembly 108 also includes an outer flange 116 carrying a plurality of holes (not shown) for set screws threadingly engaged with the second end 102 of the frame so as to permit some axial adjustment of the stub shaft assembly 108 with respect to the drum shaft 103.

A wear plate 117 is provided adjacent to the first end 101 of the frame and a wear plate 118 is provided adjacent the second end 102 of the frame so as to protect the frame ends 101 and 102 from abrasion by the mineral.

In the upper part of the drawing, the stub shaft assembly 118 is shown in its first position i.e. in the position it normally occupies during operation of the crusher.

In use of the crusher, mineral is introduced into the crusher so that it is contacted by the teeth 105 as the shaft 103 rotates and is thereby broken Into smaller pieces. In the event that some or all of the teeth become worn or broken, the appropriate crusher rings can be replaced as follows:

A stop bar 120 is inserted into the crusher so that its free end enters into a peripheral recess 119 provided in the first end 107 of the drum shaft 103 and prevents axial movement of the drum shaft. Then, the wear plate 118 at the non-drive end of the crusher is removed as is the end cover plate 115 and the retaining bolt 114 holding the stub shaft assembly 108 and the drum shaft 103 together. A support 121 is temporarily located under the drum shaft 103 at the drive end side of the centre line 122 of the drum shaft 103 to support the drum shaft during the subsequent procedure.

Alternati ely, a chain hoist may be taken around the shaft in order to support the shaft while the non-driven end is unsupported following removal of the stub shaft assembly 108. The set screws connecting the flange 116 of

the stub shaft assembly 108 and the second end 102 of the frame are then removed. Between the holes in the flange 116 for the set screws there are provided threaded holes (not shown) in which are threaded jacking screws (not shown). Rotation of these jacking screws displaces the stub shaft assembly 108 slightly away from the second end 102 of the frame (i.e. leftwards as shown in the drawing). This initial displacement is merely sufficient to enable the threaded jacking stud 123 and nut 124 to be inserted between the flange 116 and the second end 102 of the frame. Rotation of these nuts 124 is then effected in order to retract the stub shaft assembly to a second position as shown in chain dotted lines in the bottom half of the drawing. In this position, there is a gap 125 between the free end 109 of the stub shaft assembly 108 and the second end 111 of the drum shaft 103. This gap 125 is arranged to be greater than the axial width of the crusher rings 104 and spacer rings 106 and thus these rings can be slid off the drum shaft 103 and removed from the crusher via this gap 125.

When all of the rings between the second end of the shaft 103 and the temporary support 121 have been removed from the shaft, the nut 124 on the jacking stud 123 is rotated so that the stub shaft assembly is moved from its second position towards its first position through a distance sufficient to enable it to take the weight of the drum shaft 103. Then, the temporary support 121 is removed. The crusher rings 104 and spacer rings 106 which are located on the shaft towards the first end 101 can then be slid along the shaft to the second end 102. The temporary support 121 is then replaced and then stub shaft assembly 108 is then retracted once more to its second position so that the remaining rings can be removed from the second end 111 of the drum shaft as described above.

Replacement rings are then assembled onto the drum shaft 103 by a reverse of the foregoing procedure.

In an alternative embodiment, the necessary axial movement of the stub shaft assembly 108 during replacement of the crusher ring is achieved by means Of a double acting hydraulic attachment.