US2189441A - Apparatus for crushing or grinding ore - Google Patents

Description

Feb. '6, 1940. J, w, BELL 2,189,441

APPARATUS FOR CRUSHING OR GRINDING ORE Fi'led Sept. 15, 1936 2 Sheets-Sheet 1 4/ 34549 ass Feb. 6, 1940. J. w. BELL APPARATUS FOR CRUSHING OR GRINDING ORE Filed Sept. 15, 1936 2 Sheets-Sheet 2 Invenior:

2'7 06 2 M MM Patented Feb. 6, 1940 l K PATENT OFFICE APPARATUS FOR CRUSHING OR GRINDING ORE John W. Bell, Montreal, Quebec, Canada Application September 15, 1936, Serial No. 100,891

9 Claims.

I This invention relates to methods of and apparatus for crushing or grinding ore, rock and other materials, and more particularly to methods and apparatus in which the crushing or grinding ac-' tion is effected in whole or in part by the direct pressure of a crushing agency applied through centrifugal force.

I The invention has among other objects the utilization of a controlled crushing pressure in grinding operations, the establishment and maintenance of a thin, even flow of the materials to be crushed. across the face ofa crushing agency, and

the utilization in conjunction with direct pressure also of a shearing action on the materials to be .cruushcd or ground. These and other objects of the invention will be best understood by the following description when taken in connection with the accompanying illustration of one specific embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings: Fig. 1 is an elevation, in partial section and partly broken away, showing the principal work-- form of the invention; and Fig. 2is a fragmentary plan showing certain parts illustrated in Fig. 1.

Referring to the drawings and to the embodiment of the invention submitted for illustrative purposes, the ore crushing machine comprises a frame-work designated generally by the numeral l on which is supported the large annular ring die 3, against the inner face of which the ore is.

to be crushed. The frame also provides journaling support for the upright driving shaft ,5 positioned concentrically with relation to the ring die and carrying one or more crushing rollers 1 (herein, by way of example, eight in number) of substantial mass.

5 force for" crushing the ore as the latter is fed between the inner face of the ring and the outer faces of the rollers.

Referring first to the ring die 3, the latter is in the form of a continuous-annular ring of feeing parts of a crushingmachine embodying one Each roller is freely and individually rotatable about an upright axis and is tangular cross section having its outer face abutting against the inner face of a retainer ring 9 and resting on a small sill or shoulder ll presented by the retainer ring and clamped to the latter by the overlying clamping lugs l3. The retainer ring is constructed of slightly spaced segments (see Fig. 2) united by bolts 15, which latter, when tightened, lock the ring die fast in its retainer ring. The retainer ring rests on a bed plate ll where it is held against lateral movement by three centering screws l9 (one of which only is shown in Fig. 1) When the ring die is installed in the retainer ring it is brought into concentric relation to the axis of the driving shaft 5 by means of the centering screws l9, after which the retainer ring is bolted to the bed plate by stud bolts 21 which pass through the retainer ring with sufficient clearance to permit the centering adjustment referred to.

To rotate the rollers through their orbital path there is provided the driving motor 23 adapted to drive the driving shaft 5 through the beveled.

' pinion 25 and beveled gear 21, the latter keyed to the shaft by the key 29. Secured to the shaft to rotate therewith is the supporting structure or table 31 which serves as a support for the crusher rollers I, together with their journals and guides and various other parts of the apparatus, including those for controlling and regulating the centrifugal crushing pressure developed by the rotation of the planetary structure of which the rollers form a part.

Each crushing roller comprises the hardened steel outer ring or tire-like member shrunk on a ring core 33 which in turn is clamped by bolts 35 between upper and lower plates 31 and 39. Carried by the respective upper and lower plates are short stud shafts 4i journaled to rotate freely in bearings, preferably of the roller type, the upper bearing 43 with its stud shaft only being shown (Fig. 1). These bearings are carried by upper and lower plates 45 and 41, respectively, the lower plate having upright side members terminating in top flanges to which the upper plate is bolted, the three parts 45, 41 and 49 constituting a box-like carriage in which the crushing roller is journaled and carried. This carriage rests through the lower plate 41 on the supporting table 3| and is guided thereon for a radially outward and inward movement by means of gibs 5| secured to the table, so that, as regulated by the controllingdevices to be described, when the supporting platform is rotated, the rollers may move simultaneously outward in a radial but straight line direction with relation to the ring die toeifect ring action, the described conlicated for each roller of the ment corn; ising front plate or head 51', the edges of the nt plate clearing the surrounding walls of the spring cage and permitting movement of th latter with relation to the front plate. The front ate is fixed in position on the end of the tension rod 5& by the adjusting nut 6| and locking nut the rod, except for the adjustment herein c ccribed, being also fixed and the result being that 'ne front abutting plate 51 for the spring occupies a definitely fixed position with relation to the axis of the machine.

The spring when installed is preferably placed under compression with a definite force (one ton, by way of example) and is maintained in this condition when the mechanism is at rest by means of four bolts 65, the ends of which pass loosely through the back plate with their heads seated there agains but are fixedly threaded into the front plate 57? and there held by the lock nuts 67.

The result is that normally when the machine is at rest, while the roller carriage is held by the bolts 65 at a fixed position radially with relation to the ring die, which position depends on the position of the tension rod 59 and on the degree of compression of the spring, the carriage may move radially outward when the centrifugal force, under operation of the machine, becomes sufficient to further compress the spring, the back plate 55 with the ca; iage moving freely over the bolts and relatively to the fixed abutting plate 5?.

The method of establishing and maintaining a definite centrifugal crushing force will now be clear by the aid of an illustrated numerical example. If it is assumed that the roller and its carriage, due to their masses, the distances of their centers of gravity from the central axis of the machine and the rate of speed of rotation of the shaft, will develop a centrifugal force of seven tons, and further that the spring 53 under this force will compress of an inch, if the rollers when at rest are so adjusted by the tension rod and the initial compression of the spring 53 as to clear the face of a truly concentric ring die by of an inch, then, when the shaft reaches its rated speed, the centrifugal force becomes absorbed by compression of the spring, the rolls will just graze the vertical faces of the ring die and the force applied to the latter will be zero in magnitude. If, however, all of the carriages for the eight rollers are moved out radially of an inch, as by the adjustment of the tension rod, the spring will then compress of an inch, absorbing six tons of the centrifugal force and the remaining component of one ton is exerted by each roller against the ring die. Obviously by advancing or retracting the rollers radially, any force from the maximum of seven tons down to zero may be established at the crushing surfaces and maintained definitely so long as the speed of rotation is maintained at a constant rate but a part of the centrifugal force developed will always be absorbed in the spring as spring compression when the machine is in operation in order to preserve even wear of the rollers and ring die. In the case of each roller carriage, when the machine is in operation, the carriage moves radially outward and compresses the spring until the centrifugal force is in equilibrium with the total counter pressure comprising spring pressure plus the pressure against the ring die.

To provide for the adjustment of the effective crushing force, means are embodied for simultaneously moving each tension rod radially and thereby adjusting the static or normal position of each roller carriage, such means being operable during the rotation of the machine.

For this purpose each tension rod 59 extends radially inward and terminates in a portion which passes through and has threaded engagement with the threaded bore of a worm gear 69, the several worm gears being journaled in the wall ll of a drum-like structure which is fixedly secured to the supporting table 3|. Each worm gear 59 serves as a mechanically actuated nut, which, when turned, adjustably moves the carriage and its roller outwardly or inwardly.

Each pair of adjusting worm gears (Fig. 2) is in engagement with a vertically positioned worm shaft 73. The upper end of each of the several worm shafts, herein four in number (see Fig. 2), carries a spur gear 75, which gears are symmetrically disposed about and meshed with a central spur pinion 'i'l concentric with the driving shaft 5.

If, therefore, the pinion I! is turned relatively to the shaft 5, the several worm gears 69 are each rotated through gears '15 and worm shafts l3, and the several tension rods are simultaneously moved radially in one direction or the other, thereby shifting the roller carriage and rollers with relation to the ring die. Since each worm shaft 73 turns one worm gear clockwise and the other counterclockwise, their respective tension rods are provided with right-hand and left-hand threads, respectively, so that all roller carriages are moved in the same direction and to an equal extent for any movement of the pinion I! with relation to the shaft 5.

The pinion ll is fixedly secured to an elongated sleeve 19 which fits telescopically over the upper end of the central drive shaft 5, the upper end of the sleeve terminating in a shaft on which is secured a brake-drum 83. The latter is encircled by a brake-band 85 which, through the hand wheel 8'! and shaft 89, may be caused to apply at will a delicately graduated friction to the brakedrum to more or less retard its movement.

The frictional fit of the sleeve 19 over the shaft 5 is such that when the machine is in normal operation and when the brake-drum is freed from the brake-band, the sleeve rotates with and at the same speed as the shaft, the pinion '11 thereupon turning with the shaft and with the entire rotating structure and having no effect on the radial position of the tension rods. The fit of the sleeve 75 on the shaft 5, however, is also such that when the shaft 5 is being rotated, the movement of the sleeve may be slightly checked and retarded relatively to the shaft by applying the brake-band so that the shaft will then turn relatively to the pinion and effect a longitudinal movement of the tension rods. The connections are such that a slowing down of the sleeve with relation to the movement of the shaft effects a radially outward movement of the tension rods. This provides an ore crushing machine in which the crushing pressure may be regulated at will within close and minute gradations to suit the requirements of any particular ore, rock or other material to be crushed. This will be best understood by a numerical example, submitted solely for" illustrative purposes and explaining one 7 method of adjusting the machine to provide the required crushing pressure.

Let it be assumed, by way of illustration, that the most economical grinding pressure for a given ore or other material is one ton and that the centrifugal force developed at each roller at the rated speed of the machine is seven tons and that such force will compress the springs 53 each of an inch. The rollers would then be adjusted so that with the machine at rest each roller is exactly of an inch away from the face of the ring die. Such adjustment may be made in the first instance by the adjusting and locking nuts Bi and 63 on the endof the tension rods.

In practice the machine is preferably equipped with an ammeter 9i registering the current consumption of the driving motor 23. Previous tests will have established the particular reading of the motor ammeter corresponding to the most economical grinding pressure for a given class of material at a given rate of feed and at the rated speed of the machine, which pressure in the above example has been assumed tobe one ton. The machine having been brought up to speed, the

brake-band is then applied to the brake-drum 83 with a suificient pressure to slightly retard the movement of the sleeve 19 with relation to the shaft 5, such retardation being maintained until the checked movement of the pinion T! and the resulting outward movement of the roller carriages and rollers produce the desired pressure, which will be indicated by the reading on the motor ammeter. The brake-band is then freed from engagement with the drum.

If it be assumed that the main shaft 5 normally turns at a speed of revolutions per minute and the brake-drum and its attached sleeve and pinion are slowed down to 99 revolutions per minute, the gearing interposed between the tension rod and the pinion may be readily proportioned so that the outward movement of the rollers in the entire period of one minute would amount to no more than 7 of an inch. It will therefore be seen that this mechanism permits an extremely minute regulation of crushing pressure and at the same time a regulation Within wide limits from zero. to maximum.

As the ring die and roller surfaces wear the crushing pressure drops. This is accompanied by a corresponding drop in the power consumption which will be indicated by the motor ammeter reading. It is then merely necessary to apply sufiicient brake pressure to advance the rollers the distance required to again raise the current reading on the ammeter to a point corresponding to a one ton roller pressure.

A marked advantage secured by the use of a controlled crushing pressure lies in securing an even wear of the ring die and of the roller tires. In machines of the prior art utilizing centrifugal crushing pressure and where the latter has been uncontrolled, any localized Wear tends to produce a rapidily increasing flattened face so that the ring die and roller tires are required to be frequently removed from the machine and reshaped or trued up in a lathe. Such parts, therefore, not only require frequent removal and reshaping but are relatively short lived. In the crushing. machine hereindescribed, however, the

control of the centrifugal crushing force acts automatically to establish and maintain true circular contacting surfaces in both the rollers and the ring die. For illustration, taking the previous example, where the crushing force has been ad-' justed for one ton, if the inner face of the ring dieis or becomes at any time other than truly circular in form, and if for instance it presents a section the inside of which projects inwardly {a of an inch beyond the limits of a true circle, then when any roller reaches this projection it automatically applies a crushing force of two tons, thereby producing a rapid wear which soon corrects that irregularity. Conversely, if the ring die has a concave section of an inch deep, the crushing action on such section becomes zero. The result is that approximately true circular surfaces are maintained on both the ring die and rollers, the grinding pressure being automatically altered to correct any deviation from that condition. With this condition established and maintained, the grinding pressure will remain approximately uniform and the grinding surfaces protected against uneven wear. This serves to reduce the wastage or wear of metal in the die and rollers and to reduce overgrinding, unnecessary power consumption, and cost of crushing per ton.

Referring now to the means for effecting feed of the materials to the crushing agencies, such material, whether in the form of dry solids or solids With water and constituting pulp, are delivered to and caused to pass down the inclined trough or feed launder 93 to the stationary feed box 95, which latter comprises a drum encircling the sleeve 19 and carried at the end of the trough 93. Within the feed box there are provided one or more lugs or arms 91 secured to and rotatable with the sleeve 19. Such lugs serve to stir and distribute the materials and cause them to pass down through a narrow annular slot-like orifice 99 in the bottom of the feed box and concentric with and closely surrounding the sleeve '19.

Beneath the feed box and secured to the sleeve 19 to rotate therewith is a centrifugal revolving feed plate lill in the form of a flat disk, the peripheral edges of which terminate just short of the surrounding cylindrical casing I03 resting on the retainer ring 9 so as to leave an annular opening at the periphery of the feed plate. The materials are delivered through the annular orifice 99 in the feed box to the feed plate itl in the form of a uniformly distributed annulus beneath the orifice. The centrifugal force developed by the revolving feed plate causes this accumulation of material to advance radially outward, separating and spreading evenly over the entire surface of the plate and being discharged therefrom evenly and uniformly over its peripheral edges. Beneath the edge of the feed plate thematerial so advanced is allowed to pile up on the ring die, as indicated in Fig. 1, until the angle of repose is reached, When further accession to the accurnulationfrom the feed plate causes the materials to flow down over the inner face of the ring die in a thin stream, evenly distributed around the ring die face and of a substantially uniform thick mass or body. This permits the crushing rollers to exert each its crushing force on individual particles with a minimum of cushioning effect and secures a maximum efficiency in the application of such crushing force.

In machines of the prior art it has been common practice to concentrate more or less the delivery of the materials at some point or position in the path of the crushing rollers themselves so that the rollers and scrapers are relied on to distribute such materials and carry them around the ring die. This is not only wasteful of power in maintaining the rotation of the mass of pulp, but also prevents the effective application of the crushing force due to the cushioning effect of relatively thick masses of pulp between the ring die and the crushing faces of the rollers.

The material crushed between the ring die and the rollers drops into an underlying stationary annular hopper I95, the walls of which are downwardly and inwardly inclined to provide an annular trough at its bottom having a discharge opening I0? at some point in the apex of the trough immediately above a downwardly and outwardly inclined trough I051. The crushed material gravitating to the bottom of the hopper is carried around the bottom trough thereof and discharged through the opening IB'I by means of stirring members I II depending from the bottom of the rotary table 3| or by means of air currents developed by the rotating parts, or in part by both means.

From the trough I09 the crushed materials pass through an opening H3 at the side of the machine, whence they may be conveyed by suitable means, such as a centrifugal pump or air lift (not shown), to a classifier of any usual construction arranged in a closed circuit with the described grinding machine, the materials of the required degree of fineness overflowing and being withdrawn from the classifier and the coarser materials requiring further grinding being returned to the feed trough of the crushing machine. Such provisions are well known and they are not herein illustrated.

Means are also herein provided to add to the crushing or grinding effect produced by direct pressure against the materials and herein secure through the centrifugally actuated rollers also an additional shearing or rubbing action. In the illustrated embodiment of the invention this is accomplished by causing the rollers, while pressed against and rolling over the particles of material flowing down the vertical face of the ring die, to so move relatively to the ring die as to exert also a frictional rubbing or shearing action on such particles. Such shearing action may be desirable in certain cases where finer grinding is required.

The shearing action is herein secured by causing the drive shaft 5 during its rotation, together with the supporting platform 3I and parts secured thereto, to be periodically raised and lowered thereby causing each roller to be slightly raised or lowered during its travel around the inside face of the ring die, with the result that an additional amount of crushing is produced by the vertical sliding action of one crushing face over the other.

While hydraulic or various other devices may be employed for securing the vertical reciprocatory movement of the roller carriages, herein the shaft 5 is periodically raised and lowered to a slight extent by the operation of an eccentric H5 and eccentric drive shaft operatively related to the bottom of the shaft 5 and driven when desired from the rotary movement of the shaft itself.

For this purpose the lower end of the shaft 5 is mounted in a thrust or step bearing II! and is additionally journaled in a radial bearing II9,

this hearing being contained in a bearing box IZI which is adapted to have a sliding up and down movement in a bearing I23 in the machine frame but is prevented from turning by a key and slot connection 425.

An upper radial bearing I21 for the drive shaft 5 is similarly contained in the bearing box I29, being adapted for sliding up and down movement in a bearing 3| in the machine frame but prevented from turning by the key and slot connection I33.

To periodically raise and lower the shaft, the bearing box I2! at the bottom of the drive shaft is connected to an eccentric strap or link I35 operatively related to the eccentric II5 so that, as the latter is turned, the shaft is slowly raised and lowered.

To turn the eccentric a pinion I3! is fixedly secured on the shaft 5 and meshes with a gear I39 which in turn drives a vertical worm shaft MI The worm shaft I4I engages with the worm gear I43 mounted on a shaft which is adapted to be clutched to and unclutched from the eccentric II5 by means of a clutch indicated conventionally at I45. When the clutch is thrown in, the eccentric acts periodically to raise or lower the drive shaft, carrying with it the supporting table 3|, the rollers, roller carriages and connected parts, the feed plate IUI, sleeve I9 and brake drum 83, and in fact the entire rotating structure. Relative vertical movement between the shaft and the bevel driving gear 2'! is permitted by the key and slot connection I41. The desired shearing effect may be secured by a relatively slight up and down movement of the shaft and this may be confined to an amount representing a fractional part of the Width of the inner ring face of the die so that the rollers in their uppermost position will overlap somewhat the upper edge of the ring die and in their lowermost position will slightly overlap the bottom edge.

In many cases where fine grinding by the shearing action is unnecessary to the purpose for which the material is required, the resulting rubbing or shearing action would merely increase the Wear on the ring die and roller tires and the grinding cost per ton. The formation of thin projections on the ring die or rollers, due to slight difference in width, may be avoided by raising the shaft bearing box I2! and there maintaining it so that the rollers are caused to rotate for a given period while overlapping slightly the upper edge of the ring die and then subsequently lowering the shaft bearing box and there maintaining it so that the rollers are then caused to rotate while overlapping slightly the lower edge of the ring die, the direct centrifugally actuated pressure of the rollers only being relied on in each case without any shearing or rubbing action. Such positions of the drive shaft may be established and maintained by turning and locking the eccentric while unclutched from the drive shaft, or for the eccentric there may be substituted other means such as a mechanical or hydraulic jack.

While I have herein shown and described for the purposes of illustration one specific embodiment of the invention, it is to be understood that extensive deviations may be made therefrom in the form, construction and relative arrangement of parts, all without departing from the spirit of the invention.

I claim:

1. In a machine for crushing ore or other mahaving a surface 'on which the materials to be crushed are presented, crushing means comprising a plurality of tcentrifugally actuated crushing rollers movable radially outward under centrifugal force, means for carrying said crushing rollers in an'orbital path in cooperative relation to the annular member, connections for the several rollers comprisinga spring for each, the springs for the severalrollers being initially compressed under a similar compression in the static position of the carrying means,..the spring for each roller being capable at 'normalsp'eed of absorbing by cor. pression all of the'centrifugal force developed by the roller, amember for each roller having a fixed position'in the normal operation of the machine, and means to simultaneously adjust said members for the different rollers to riadally advance the static position of each roller toward the'annular member until contact is had therewith, and to further adjust said members until each reaches its said normal fixed position; I '2. In a machine for crushing ore or like materials, the coinbination with an annular ring die of a rotatable supporting structurerotatable about an axis concentric with said ring die, crushing means comprising a roller and roller support movably supported on said structure and movable outwardly under centrifugal force, a compression spring interposed between the structure and the roller support to resist centrifugal force, a first abutment acting against one end of the spring and having a position during the normal operation of the machine unaffected by outward centrifugally enforced movement of the roller support, a second abutment acting against the opposite end of the spring secured to and movable with the roller support to compress the spring, and means to adjust the radial position of said first abutment outwardly while the machine is in running operation, thereby to move the roller support until the roller has grazing contact with the ring die and on further outward adjustment to relax the spring to increase the crushing force at the ring die. i

3. In a machine for crushing ore or like materials, the combination with an annular ring die of a rotatable supporting structure rotatable about an axis concentric with said ring die, crushing means comprising a roller and a roller support supported on said structure and movable outwardly under centrifugal force, a spring the deformation of which resists centrifugal force located between-the structure and the roller support, a member secured to and movable with the roller support and having operative connection with one end of the spring and having a postion during the normal operation of the machine unaffected by outward centrifugally enforced movement of the roller support, an opposite end of the spring having operative connection to the outwardly movable roller support, and means to adjust the radial position of said member outwardly while the machine is in running operation, thereby to move the roller support and spring bodily outward until the roller has grazing contact with the ring die and on further outward adjustment to relax the spring to increase the crushing force at the ring die.

4. In a machine for crushing ore or other materials the combination with an annular member having a surface on which the materials to be crushed are presented, of crushing means comprising a plurality of centrifugally actuated crushing rollers each with its roller support, the

said plurality of rollers and roller supports being movable radially outward under centrifugal force independently of each other, means for carrying said crushing rollers in an orbital path in operative relation to the annular member, a separate spring for each roller, means operatively mounting each spring between its respective roller and roller support to absorb a part of the centrifugal force under which saidrollers are urged toward the annular member, and an adjustable connecting member for each of said springsadjustable during the running operation of the machine to simultaneously adjust the crushing pressure of the rollers for any given rate of rotation of the machine. I

5. In a machine for'crushing ore or other materials the combination with an annular member having a surface on which the materials to be crushed are presented, of crushing means comprising a plurality of centrifugally actuated crushing rollers each with its roller support, the said plurality of rollers andjroller supportsbeing movable radially outward under centrifugal force independently'of each other,-means for carrying said crushing rollers in an orbital path in operative relation to the annular member, separate resilient means between each of said rollers and its respective roller support for absorbing a part of the centrifugal force under which each roller is urged toward the annular member and adjustable means operable during the running operation of the machine for varying the amount of centrifugal force absorbed by the resilient means.

6. In a machine for the fine crushing of ore, or other materials, the combination with a ring die of a horizontal supporting structure rotatable about an axis concentric with said ring die, a

plurality of crushing members carried by saidv structure in an orbital path concentric with said ring die, each comprising a crushing roller ro-tata-. ble on its own axis mounted on a roller carriage which in turn is mounted on the horizontal supporting structure, the carriage and crushing roller being movable outward as a unit horizontally under the urge of centrifugal force, a spring in which all effective centrifugal force generated by the mass and velocity of the roller and roller carriage is balanced, adjustable means in connection with said spring andoperative while the machine is running to, move the roller and carriage outward first until the roller makes grazing contact with the ring die, and then further to move said roller and carriage 'to release any fraction of the centrifugal force balanced in the spring whereby the same is applied as crushing force on the face of the ring die and the fraction of the whole centrifugal force selected as the most efficient crushing force'for a given ore may be applied and maintained. i

'7. In a machine for the fine crushing of ore or other materials, the combination with a ring die of a horizontal supporting structure rotatable about an axis concentric with said ring die, a plurality of crushing members carried by said structure in an orbital path concentric with said ringdie, each comprising a crushing roller rotatable on its own axis mounted on a roller carriage which in turn is mounted on the horizontal supporting structure, the carriage and crushing roller being movable outward as a unit horizontally and radially under the urge of centrifugal force along a fixed and unchanging radius drawn from the center of the ring die through the center of the roller, a spring, in which all effective centrifugal force generated by the mass and velocity of the roller and roller carriage is balanced, adjustable means in connection with said spring and operative while the machine is running to move the roller and carriage radially outward first until the roller makes grazing contact with the ring die, and then further to move said roller and carriage to release any fraction of the centrifugal force balanced in the, spring whereby the same is applied as crushing force on the face of the ring die and the fraction of the whole centrifugal force selected as the most efficient crushing force for a given ore may be applied and maintained.

8. In a machine for crushing ore or other materials, the combination with an annular ring die, of a cooperative, radially and outwardly movable, centrifugally acuated, crushing roller, a rotatable supporting structure for said roller for carrying it through an orbital path in operative relation to the ring die, a spring the deformation of which resists centrifugal force and limits the outward movement and crushing force of the roller, said spring constituting a part of the connection be tween said roller and said carrying means, spring relaxing means operative when the roller is in contact with the ring die for releasing the spring to augment the centrifugal force developed as crushing force by the roller, and means for adjusting said relaxing means including a device mounted concentrically with the axis of rotation of said structure and operative while the machine is running.

9. In a machine for crushing ore or other materials, the combination with an annular member having a surface on which the materials to be crushed are presented, of crushing means comprising a plurality of centrifugally actuated crushing rollers each with its roller support, a rotatable structure carrying said roller supports, said plurality of rollers and roller supports being movable radially outward under centrifugal force independently of each other, separate resilient means between each of said rollers and its respective roller support for absorbing a part of the centrifugal force under which each roller is urged toward the annular member, means for adjusting said resilient means for varying the amount of centrifugal force absorbed thereby, and controlling means including a member mounted concentrically with the axis of rotation of said structure and operable during the running of the machine to simultaneously adjust each of said resilient. means.

JOHN W. BELL.

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