US3220658A

US3220658A - Hammermills

Info

Publication number: US3220658A
Application number: US160097A
Authority: US
Inventors: Jr Harry J Shelton
Original assignee: GRUENDLER CRUSHER AND PULVERIZER
Current assignee: Lukens General Industries Inc; General Steel Industries Inc
Priority date: 1961-12-18
Filing date: 1961-12-18
Publication date: 1965-11-30
Anticipated expiration: 1982-11-30

Description

' Nov. 30, 1965 H. J. SHELTON, JR

HAMMERMILLS 3 Sheets-Sheet 1 Filed Dec. 18, 1961 HARRY J. SHELTON. JR W ATTORNEY H. J. SHELTON, JR

HAMMERMILLS Nov. 30, 1965 Filed Dec. 18. 1961 68. 68h 685. 682 6s? 3s 3 Sheets-Sheet 2 FIG. 3

FIG 4 INVENTOR.

HARRY J. SHELTON, JR.

ATTORNEY Nov. 30, 1965 H. J. SHELTON, JR 3,220,658

I06 N07 96 I00 FIG.7

IN VEN TOR. HARRY J. SHEL'TON, JR.

ATTORNEY United States Patent 3,220,658 HAMMERMILLS Harry J. Shelton, Jiu, Ladue, Mo, assignor to Grueudler Crusher & Pulverizer Co., St. Louis, Mo, a corporation of Missouri Filed Dec. 18, 1961, Ser. No. 160,097 12 Claims. (Cl. 24186) This invention relates in general to crushers and, more particularly, to an improved type of hammermill.

In the operation of hammermills, it is frequently necessary to make various repairs. Highly abrasive materials wear out the hammers rather rapidly and, consequently, hammers must be replaced from time to time. In certain types of input, iron and random masses of extremely hard relatively non-crushable material often enter the hammermill cage and jam or damage the hammers in such manner that the hammermill must be shut down and completely dissassembled in order to remove the jammed material or make other repairs. These shutdown operations, of course, are laborious, time-consuming, and, therefore, rather costly.

It is, therefore, the primary object of the present invention to provide a hammermill that is designed to provide rapid and convenient access to the internal portion of the device.

It is another object of the present invention to provide a hammermill of the type stated that will crush substances to be pulverized therein by means of a positive impact between the hammers and breaker plates forming part of the mill.

It is an additional object of the present invention to provide a hammermill of the type stated which cannot be seriously damaged by oversized material, tramp iron, or other relatively non-crushable material.

It is a further object of the present invention to provide a hammermill which can be readily disassembled for hammer replacement and other repairs whenever necessary.

It is also an object of the present invention to provide a hammermill of the type stated which is sturdy in construction and economical in cost of manufacture and in operation.

With the above and other objects in view, my invention resides in the novel features of form, construction, atrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (three sheets):

FIG. 1 is a perspective view of a hammerrnill constructed in accordance with and embodying the present invention;

FIG. 2 is an exploded perspective view of the hammer mill;

FIG. 3 is an end elevational view of the hammermill;

FIG. 4 is a top plan view of the hammermill;

FIGS. 5, 6, and 7, are sectional views taken along lines 5-5, 66, and 77, respectively, of FIG. 4; and

FIG. 8 is a fragmentary sectional view taken along line 88 of FIG. 6.

Referring now in more detail and by reference characters to the drawings, which illustrate a preferred embodiment of the present invention, A designates a hammermill comprising a substantially rectilinear cage-base 1 including two spaced parallel

lateral walls

2, 3, integrally connected along one transverse margin by a relatively short vertical wall v which merges at its upper margin into an inwardly and upwardly inclined cross-plate 4. At their opposite ends, the

lateral walls

2, 3, are cross-connected by a vertical back-wall 5 which is preferably welded along its abutting margins to the interior faces of the

lateral walls

2, 3, and is integrally provided along its upper and lower horizontal margins with inwardly projecting

horizontal flanges

6, 7. The

lateral walls

2, 3, are

"ice

also integrally provided along their lower horizontal mar gins with outwardly projecting

horizontal flanges

8, 9, respectively.

Along their upper margins, the

lateral walls

2, 3, are centrally cut away in the provision of downwardly extending rectilinear recesses 10, 11, which are of substantially the same size and shape and are aligned with each other transversely across the cage-base 1. Along its upper horizontal margin on either side of the recess 10, the lateral wall 2 is provided with outwardly extending horizontal flanges 12, 13, and similarly, on its upper horizontal margin on either side of the recess 11, the lateral wall 3 is provided with outwardly extending

horizontal flanges

14, 15. Welded to the outer face of the lateral wall 2 and the upper face of the flange 8 thereof is a pair of laterally spaced vertical gusset plates 16, which are, in turn, welded to the under face of and support a horizontal bracket plate 17 located directly beneath the horizontal margin of the recess 11) for supporting the lower half of a pillow block 18 secured thereon by bolts or other suitable attachment means. Similarly welded to the outer face of the lateral wall 3 and the upper face of the flange 9 is a pair of gusset plates 19, which are, in turn, welded to the under face of and support a horizontal bracket plate 20 located directly beneath the horizontal margin of the recess 11 for supporting the lower half of a pillow block 21 secured thereon by bolts or other suitable fastening means. The pillow blocks 18, 21, are, of course mounted in coaxial alignment with each other, all as best seen in FIG. 2 and for purposes presently more fully appearing.

Welded upon the upper face of the flange 12 is a vertical side plate 22 having vertical margins which are in alignment, respectively, with the vertical margins of the lateral plate 2 and the recess 10, and which is precisely coplanar on its inner face with the inner face of the lateral wall 2. Along its upper horizontal margin, the side plate 22 is integrally provided with an outwardly extending horizontal flange 23 and, on its interior vertical margin, is similarly provided with a short vertical flange 24, the latter being provided with a plurality of vertically spaced apertures or so-called bolt-holes 25. Provided for re movable disposition upon the flange 13 is a side plate 26 which is substantially similar in shape and construction to the side plate 22 and integrally includes upper and lower

horizontal flanges

27, 28, the latter being bolted to the flange 13. The side plate 22 is also provided with a short vertical flange 29 matching the vertical flange 24 and being similarly provided with a plurality of apertures or so-called bolt-holes 30. Provided for removable disposition between the

side plates

22, 26, when the latter is bolted in place, is a filler plate 31 having outwardly extending

vertical flanges

32, 33, which fit facewise against the

flanges

24, 29, and are provided with sets of bolt-

holes

34, 35, which respectively match the sets of bolt-

holes

25, 30, so that the tiller plate 31 may be secured in place by sets of bolts 36, 36'. The filler plate 31 is coplanar on its inwardly presented face with the inward faces of the

side plates

22, 26, and is substantially shorter in vertical height than the

side plates

22, 26, so that its downwardly presented horizontal margin is spaced upwardly above the

flanges

12, 28, by a distance substantially equal to the vertical depth of the recess 10.

Welded upon the upper face of the flange 14 is a vertical side plate 3'7 having vertical margins which are in alignment, respectively, with the vertical margins of the lateral plate 3 and the recess 11, and which is precisely coplanar on its inner face with the inner face of the lateral wall 3. Along its upper horizontal margin, the side plate 37 is integrally provided with an outwardly extending horizontal flange 38 and, on its interior vertical margin, is similarly provided with a short vertical flange 39, the latter being provided with a plurality of vertically spaced apertures or so-called bolt-holes 49. Provided for removable disposition upon the flange is a side plate 41 which is substantially similar in shape and construction to the side plate 37 and integrally includes upper and lower

horizontal flanges

42, 43, the latter being bolted to the flange 15. The side plate 41 is also provided with a short vertical flange 44 matching the vertical flange 39 and being similarly provided with a plurality of apertures or so-called bolt-holes 45. provided for removable disposition between the

side plates

37, 41, when the latter is bolted in place, is a filler plate 46 having outwardly extending

vertical flanges

47, 48, which fit facewise '.'against the flanges 39, 4d, and are provided with sets ofqbolt-

holes

49, 50, which respectively match the sets of bolt-

holes

40, 45, so that the filler plate 46 may be secured in place by sets of

bolts

51, 52. The filler plate 46 is coplanar on its inwardly presented face with the inwardly faces of the

side plates

37, 41, and is substantially shorter in vertical height than the

side plates

37, 41, so that its downwardly presented horizontal margin is spaced upwardly above the

flanges

14, 43, by a distance substantially equal to the vertical depth of the recess 11.

Provided for removable disposition across one transverse end of the cage-base 1 between the

side plates

26, 41, when the latter are bolted in place is an end wall 53 integrally including a relatively broad top plate 54 having a continuous depending perimetral flange 55 which is provided in its lateral face with a plurality of bolt-holes 56 for securement by means of bolts 57 to the

side plates

26, 41. Along its lower horizontal margin, the end wall 53 is integrally provided with an inwardly extending horizontal flange 58 having a plurality of bolt-holes 59 for securement to the flange 6 of the cage-base 1 by means of bolts 60.

It will, of course, be understood in this connection that the various bolts used for connection of the removable parts above described are held in place by nuts and lock washers which are entirely conventional and, therefore, are not shown or described in detail herein. As will be noted by reference to FIGS. 1 and 2, the top plate 54 extends horizontally inwardly and is coplanar on its upper face with the upwardly presented faces of the

flanges

27, 42. Moreover, the transverse portion of the perimetral flange 55 is substantially coplanar with the inwardly presented faces of the

flanges

29, 44, thereby defining and, in effect, completing the grinder cage C.

The

side plates

22, 37, are provided with concentrically aligned apertures 61, 62, for accommodating a stationary pintle-rod 63 which is integrally provided at one end with an enlarged head 64 and at its other end with a diametral aperture 65 for receiving a drive pin 66 which impinges against a washer 67 and serves to hold the pintle-rod 63 removably in horizontal position across the cage C at the opposite end thereof with respect to the end plate 53. Swingably mounted upon the pintlerod 63 is a plurality of identical closure plates 68*, 68 68 68 68 each of which integrally includes an interior wall 69,

side flanges

70, 71, and a bottom flange 72. The flanges 7h, 71, are provided with concentrically aligned apertures adapted to fit snugly, but, nevertheless rockably, upon the pintle-rod 63 and, when the several closure plates are mounted in side-by-side contiguous relation, as shown in FIGS. 1 and 2, they will form a complete closure across the otherwise open transverse end of the cage C. Each of the bottom flanges 72 is positioned at an appropriate dihedral angle with respect to the interior wall 59 so that the underface of the flange 72 will fit flush against the upwardly and outwardly presented face of the cross-plate 4 when the

closure plates

63, 68 68 68 68 are in the inwardly inclined operative position shown in FIG. 1. Furthermore, each of the bottom flanges 72 is centrally provided with an aperture 73 located for precise registration with a corresponding aperture 74- extending through the cross-plate 4 for receiving snug-fitting shear pins 75. The combined upper horizontal margins of the closure plates 68*, 68 68c, 68 68c, are spaced laterally from the transverse portion of the flange 55 to define an intake opening 0 into the grinder cage C.

Operatively mounted within the pillow blocks 18, 21, and held in place by arcuate bearing caps 76, 77, are conventional roller bearings 78, '79, respectively. Journaled in, and extending horizontally through, the roller bearings 78, 79, is a rotor shaft which is provided at one end with a fly-wheel 81 and at its other end with a V-grooved pulley 82 connected by a series of V-belts 83 to the driving pulley 84 of a conventional electric motor 85, the latter being mounted by lag bolts 86 or any other suitable means externally of the grinder cage C, substantially as shown in MG. 4.

Rigidly keyed to the rotor shaft 36 is a series of axially aligned disks 87 each integrally provided with diametrally reduced circular spacer-bosses 88, the entire assembly being locked upon the shaft between a pair of threadedly mounted locking rings 89, 90. As will be noted by reference to FIG. 6, the outwardly projecting ends of the shaft 80 are turned down to a somewhat reduced diameter so as to extend loosely and with free clearance through the rectangular apertures formed by the recesses 10, 11, and the space beneath the

filler plates

31, 46. Each of the disks 87 is provided, approximately midway between its center and its outer periphery, with four uniformity spaced apertures 91. In other words, the apertures 91 are located 90 apart in terms of circular measure around the disks S7 and, moreover, the disks 87 are aligned or oriented on the shaft 80 so that the apertures 91 are arranged in four axially aligned sets adapted, respectively, for receiving four hammersupporting rods 92. Each of the rods 92 is integrally provided at one end with a diametrally enlarged head 93 and at its other or protruding end with a diametral drill-hole 94 for receiving a drive pin 95 by which each rod 92 is held in place. Operatively mounted upon the rods 92 and located within the various spaces between the disks 87 are rectilinear or so-called bar-shaped hammers 96 which project radially outwardly for a short distance beyond the periphery of the disks 87 and are held non-swingably in such radial position between crossrods 97 mounted permanently in and extending axially through the disks 87 and backing bars 98 which are set snugly into rectangular recesses 99 formed in the peripheral margins of the disks 87, the backing bars 98 being welded or otherwise rigidly secured in place. As will be seen by reference to FIG. 7, the outside diametral size of the disk 87 is substantially smaller than the radial distance between the centerline of the shaft 8t) and the innermost margins of the closure plates 68 68*, 68, 68 68 when the latter are in operative or closureforming position.

Welded upon the interiorly presented faces of the

lateral walls

2, 3, are arcuate bottom rails Wt), 101, and upward ly spaced concentric channel-forming

top rails

102, 103. The pairs of

rails

100, 102, and 101, M93, respectively, define transversely registering screen-receiving channels 164, 105, which conform to circular arcs concentric about the centerline of the shaft 8t) and are somemhat horter in peripheral length than a full semi-circle so as to be flush at one end with the plane of juncture between the

flanges

6, 58. At their opposite ends, the bottom rails 169, 161, and the top rails 152, 103, terminate in the plane of juncture between the underfaces of the flanges 72 and the upper face of the cross-plate 4. It will be noted by reference to FIG. 7 that the swingable closure plates are normally held in place by the shear pins in overhanging relation to the inner margin of the cross-plate 4 and act as end stops across the channels 104, MP5. Operatively mounted within the channels we, 105, and extending transverse- 1y across the grinder cage C is a conventional serrated breaker plate 106 and a conventional grate bar assembly 107. Both the breaker plate 106 and the grate bar assembly 107 lie outwardly beyond the outermost peripheral limits of the hammer circle so that there is a proper amount of clearance between the ends of the hammers 96.

Welded or otherwise rigidly mounted on and forming a part of the closure plates 68 68*, 68, 68 68 are pairs of breaker-teeth 108 which project inwardly in the spaces between the hammers 96 and are of somewhat trapezoidal shape, terminating in outwardly spaced relationship to the peripheries of the disks 87 so that there is a substantial amount of clearance therebetween. Finally, a somewhat L-shaped catch pan 109 is attached in any suitable manner upon the underface of the cross-plate 4 so as to form a transversely extending chamber 110 beneath the apertures 74, all as best seen in FIG. 7 and for purposes presently more fully appearing.

In use, the hammermill A should preferably be mounted on a floor or similar supporting structure and over an opening or in any other manner so that the pulverized material passing downwardly through the grate bar assembly 107 will drop into a conventional type of discharge bin (not shown). When the electric motor 85 is energized, the shaft 80 and the disks 87, together with the hammers 96 mounted thereon, will be set in rotation in the direction shown by the arrow in FIG. 7. Rock or other material to be comminuted is fed in the usual manner downwardly through the intake opening into the grinder cage C where it will be impacted by the hammers 96. If some non-crushable material or a piece of material which is too large or too hard to be broken up by the particular hammermill A happens to enter the cage C and tends to jam the hammers 96, such material wil be forcibly wedged against one or more of the closure plates 68 68 68, 68 68 and the wedging force will shear off one or more of the shear pins 75 so that one or more of the closure plates 68 68 68, 68 68 will swing outwardly to the position shown in dotted lines in FIG. 7 and the noncrushable or jam-creating material will be hurled aside. The inherent strength of the shear pins 75 must be selected so that the shear pins 75 will give way under a wedging or jamming force which is below the permissible limits of the eliminating structure of the grinder. In other words, the shear pins 75 will break away before the Wedging force becomes great enough to do any damage to the hammers 96, the disks 87, or, for that matter, the motor 85. Of course, when one or more of the shear pins 75 is sheared, it will be necessary to shut down the hammermill A temporarily to clear away the material which has been expelled from the grinder cage C and close whichever one of the closure plates 68 68 68, 68 68 happens to be pushed open. It is, of course, obvious that the broken shear pins 75 will be replaced by new shear pins 75. Incidentally, the severed lower end of the broken shear pins 75 will drop into the space 110 and will accumulate there. The shearing action is a safety measure and should not occur too frequently during the normal operation of the hammermill A. Therefore, the severed shear pin ends will not accumulate very rapidly. Notwithstanding this, an opening is provided in the crossplate 4 and closed with a removable cover plate 111 so that, if necessity requires, the severed ends of the shear pins can be manually removed It will, of course, be evident, by reference to FIG, 2, that the

filler plates

31, 46, can very quickly be removed to provide convenient access to the hammer-supporting rods 92. If any of the hammers 96 need replacing, the particular rod 92 which supports the worn hammer or hammers 96 can be brought into alignment with the gaps left open by removal of the

filler plates

31, 46. Thereupon, the hammer-supporting rod 92 can be withdrawn and the worn hammer 96 can be removed and replaced.

Similarly, the

side plates

26, 41, and the end plate 53 can be very quickly unbolted and removed, whereupon the interior of the grinder cage C will become readily accessible for other types of repairs, such as removal and replacement of the grate bar assembly 107 or the breaker plate 106. It will be noted in this connection that the flange 58 projects over one end of the grate bar assembly 107 so that when the end plate 53 is removed, the grate bar assembly 107 can be pulled upwardly out of the channels 104, 105. Finally, by unbolting and removing the bearing caps 76, 77, the shaft 80, together with the entire hammer assembly, can be bodily removed from the grinder cage C in a very convenient and speedy manner in the event that some kind of extensive repair or replacement should be necessary with respect to the assembly of any of its components.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the hammermills may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A hammermill comprising an outer cage, a shaft rotatably mounted within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of circumferential grooves, a plurality of hammer elements disposed within each of said grooves, retaining means for securing said hammer elements within said grooves, stop means operatively associated with said retaining means for preventing rotative movement of said hammer elements within said grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

2. A hammermill comprising an outer cage, a shaft rotatably mounted Within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of grooves, at least one hammer element disposed within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed within said apertures for securing said hammer elements within said grooves, means disposed within said grooves and being operatively associated with said hammer elements for preventing rotative movement of said hammer elements within the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

3. A hammermill comprising an outer cage, a shaft rotatably mounted within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of circumferential grooves, a plurality of circumferentially spaced hammer elements disposed within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed within said apertures for securing said hammer elements within said grooves, stop means operatively associated with said rod means for preventing rotative movement of said hammer elements in the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

4. A hammermill comprising an outer cage, a shaft rotatably mounted within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of circumferential grooves, a plurality of circumferentially spaced hammer elements disposed Within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed within said apertures for securing said hammer elements Within said grooves, said drum having a recess adjacent each of said hammer elements, a backing bar disposed within said recess and being rigidly secured to said hammer elements for preventing rotative movement of said hammer elements in the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

5. A hammermill comprising an outer cage, a shaft rotatably mounted Within said cage, a plurality of axially ali ned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially disk forming a drum with a plurality of circumferential grooves, a plurality of circumferentially spaced hammer elements disposed Within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed withinsaid apertures for securing said hammer elements within said grooves, said drum having an axially extending recess adjacent each of said hammer elements, an axially extending backing bar disposed within said recess and being rigidly secured to said hammer elements for preventing rotative movement of said hammer elements in the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

6. A hammermill comprising an outer cage, a shaft rotatably mounted within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of circumferential grooves, a plurality of circumferentially spaced hammer elements dipsosed within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed within said apertures for securing said hammer elements Within said grooves, said drum having an axially extending recess adjacent each of said hammer elements, an axially extending backing bar disposed within said recess and being rigidly secured to said hammer elements for preventing rotative movement of said hammer elements in the grooves, stop means operatively associated with said hammer elements and drum for further preventing rotative movement of the hammer elements Within the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

7. A hammermill comprising an outer cage, a shaft rotatably mounted Within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft, said disks comprising a circular plate with an axially extending boss, the boss of one disk being in abutting engagement with the plate of the next axially aligned disk forming a drum with a plurality of circumferential grooves, a plurality of circumferentially spaced hammer elements disposed within each of said grooves, said hammer elements and drum having a plurality of axially extending aligned apertures, rod means removably disposed within said apertures for securing said hammer elements Within said grooves, said drum having an axially extending recess adjacent each of said hammer elements, an axially extending backing bar disposed within said recess and being rigidly secured to said hammer elements for preventing rotative movement of said hammer elements in the grooves, a pin extending axially through said drum and abutting said hammer elements on one margin for further preventing rotative movement of the hammer elements within the grooves, and means operatively associated with said hammer elements for crushing a charge of material when said shaft is rotated.

8. A hammermill comprising a cage having a front Wall, a back wall and a pair of spaced opposed side walls, said front wall including a plurality of laterally abutting pivotally mounted panels, means removably disposed in each panel for securing each such panel in a rigid position, said last-named means having limited structural strength thereby to shear transversely when an outward force in excess of a predetermined limit is applied to the panel with which it is associated, a drum rotatably mounted Within said cage, hammer means operatively mounted on said drum, means in said cage operatively associated with said hammer means for crushing a charge of material when said drum is rotated, and internal classifier means mounted beneath said drum for regulating the particle size of the crushed charge.

9. A hammermill comprising a cage having a front Wall, a back wall and a pair of spaced opposed side Walls, said front wall including a plurality of laterally abutting longitudinally aligned pivotally mounted panels, means removably disposed in each panel for securing each such panel in a rigid position, said last-named means having limited structural strength whereby to shear transversely when an outward force in excess of a predetermined limit is applied to the panel with which it is associated, a drum rotatably mounted within said cage, hammer means operatively mounted on said drum, means in said cage operatively associated with said hammer means for crushing a charge of material when said drum is rotated, and internal classifier means mounted beneath said drum for regulating the particle size of the crushed charge.

lltl. A hammermill comprising a cage having a front wall, a back wall and a pair of spaced opposed side walls, said front Wall including a plurality of longitudinally aligned vertically extending panels, separate shear pin means associated with each panel for rigidly holding each such panel in the vertical position, said shear pin means having limited structural strength whereby to sever upon the application of an outward force in excess of a predetermined limit to the panel with which the shear is associated, a drum rotatably mounted Within said cage, hammer means operatively mounted on said drum, means in said cage operatively associated with said hammer means for crushing a charge of material when said drum is rotated, and internal classifier means mounted beneath said drum for regulating the particle size of the crushed charge.

11. A hammermill comprising an outer cage, a shaft rotatably mounted within said cage, a plurality of drumforming disks mounted on said shaft and having a plurality of circumferentially extending grooves having concentric annular bottom surfaces spaced radially inwardly from the circumference of the disks, a plurality of axially extending rods mounted in spaced parallel relation annularly around the disks in proximity to the bottom surfaces of the grooves, hammer means disposed within said grooves, each being removably mounted upon one of said rods, a pair of rod-like elements extending axially through the disks on opposite sides of, and in outwardly spaced parallel relation to, each of the rods, the distance between each such pair of elements being substantially equal to the circumferential Width of the hammers so that the hammers are held non-swingably therebetween, and means operatively associated with said hammer means for crushing a charge of material when said shaft is rotated.

12. A hammermill comprising an outer cage, a shaft rotatably mounted Within said cage, a plurality of axially aligned drum-forming disks mounted on said shaft and having a plurality of circumferentially extending grooves having concentric annular bottom surfaces spaced radially inwardly from the circumference of the disks, a plurality of axially extending rods mounted in spaced parallel relation annularly around the disks in proximity to the bottom surfaces of the grooves, hammer means disposed within said grooves, each being removably mounted upon one of said rods, a pair of rod-like elements extending axially through the disks on opposite sides of, and in out- Wardly spaced parallel relation to, each of the rods, the distance between each such pair of elements-being substantially equal to the circumferential width of the hammers so that the hammers are held non-swingably therebetween, and means operatively associated with said hammer means for crushing a charge of material when said shaft is rotated.

References Cited by the Examiner LESTER M. SWINGLE, Primary Examiner.

EDWARD W. KIRBY, Examiner.