US2022000A - Apparatus for breaking material - Google Patents

Description

Nov. 26, 1935. A. A. HOLBECK APPARATUS FOR BREAKING MATERIAL Original Filed Jan. 28, 1955 5 'sne ets-she et 1 k- N MT 1 m Y NA v mw% Nov. 26, 1935. A. A. HOLBECK APPARATUS FOR BREAKING MATERIAL Original Filed Jan. 28, 1933 5 SheetsSheet 2 [N VENTOR. Ausf/n A. Ho/bec/v,

ATT'Y Nov. 26, 1935. A, A. HOLBECK 2,022,000

APPARATUS FOR BREAKING MATERIAL Original Filed Jan. 28, 1935 3 Sheets-She et 3 n3 us H3 4 08 53 no ll 1 ll 3 x g 6: I05 [06 124 lf i 53 /N VEN TO AuSf/r) A. H /b Patented Nov. 26, 1935 UNITED STATES PATENT OFFICE originalapplication January 28,1933, Serial No. 654,012. Divided and this application May 17,

1933, Serial No. 671,533

'Claims.

The 1 present invention relates to automatic heating systems thermostatically controlled, and one of the objects of the invention is =the provision of improved and efficient apparatus for in- 5 eluding in such systems a pulverizer for the combustible material to be used and operating such- A further object of the invention is the provision of a motor-operated pulverizer and feeding means therefor combined with controlling mechanism in an automatic heating system, to eifect stopping of the feeding means independently of the stopping of the pulverizer.

Another object of the invention is the provision of thermostatically controlled and automatically operated pulverizing mechanism, combined with means for feeding a mixture of air and pulverized material to a furnace burner for burning in the furnace chamber.

A further object of the invention is the provision of improved mechanism for feeding a mixture of pulverized fuel and air to a furnace burner and providing auxiliary air feeding mechanism to such burner to enable the same to burn pulverized fuel continuously without extinguish- I ment directly in the chamber of a furnace.

Another object of the invention is the provision in an automatic thermostatically controlled heating system of a pulverizer and means for feeding the pulverized material to a burner and automatically supplying an expansion gas flame for a limited period to efiectthe starting of the burner.

A further object of the invention is the provision of a thermostatically controlled automatic heating system embodying a pulverizer operated only as the pulverized material is needed in order to avoid the storage of pulverized fuel with its attendant danger of spontaneous combustion in 1 storage.

Another object of the invention is the provision in a thermostatically controlled automatic heating system embodying a motor operated pulverizer, of safety features operable under predetermined abnormal conditions to stopor prevent the operation of the system including the pulverizer.

A further object of the invention is the provision of feeding directly to a pulverizer the material to be pulverized and eliminating tramp iron to prevent the same from injuring the pulverizing elements.

Another object of the invention is the provision in an automatic thermostatically controlledheating system of a direct firing unit comprising feed- 5 ing, pulverizing, mixing burner and. initial ignition mechanism, to enable a self-sustaining fuel I flame to be maintained continuously directly in the furnace chamber of the heating system.

The present application is a division of apl0 plication Ser. No. 654,0l2,-fi1ed January 28, 1933.

In the accompanying drawings, Fig. 1 is an elevation of a thermostatically controlled automaticheating system embodying the present invention;

Fig. 2 is an enlarged sectional elevation of the feeding mechanism and. the pulverizing apparatus shown in elevation in the right-hand portion of Fig. 1;

Fig.3 is a sectional view taken on the line 3-3 20 of Fig. 2;

Figs. 3a and. 4 are perspective views of opposite faces of the fan side of the rotor element of the pulverizer shown in section in Fig. 2;

Fig. 5 is a perspective view of the inner face of the feed side rotor element of the pulverizer;

Fig. 6 is an enlarged sectional elevation of an electric ignition device adapted to be attached to the furnace burner shown in Fig. 1;

Fig. 7 is a wiring diagram of the electric circuits and the connections for the heating system shown in Fig. 1;

Fig. 8 illustrates a modified heating system embodying a separate motor for operating the mechanism for feeding the material to the pulverizer,

and including the addition of an auxiliary air supplying mechanism for the burner; and

Fig. 9 is a wiring diagram of the circuits and connections for the heating system shown in Fig. 8. i

In the accompanying drawings, l0 designates a furnace having a furnace chamber H, to. which the present improved direct firing unit is adapted to be connected. The burner l2 of said unit comv prises concentric, spaced-apart tubes both open at their inner ends into the furnacechamber H and both closed at their outer ends as shown in Fig. 1. A feed pipe I5 communicates at it with the cylindrical space between the tubes l3 and M, and'when'the mixture of air and. fuel is projected into the said cylindrical space, it passes into the furnace chamber I l through-the annular burner opening at H. Y

A gas igniting burner I8 is connected to the end of the gas pipe [9 extending along the center 55.

of the inner tube l4. Such burner may comprise a constantly burning pilot and an expansion burner; the pilot being regulated by the hand operated valve 20 and the expansion-burner being controlled by the electromagnetic valve 2|. When the latter is opened, the gas flowing from' the supply pipe 22 through the expansion burner produces a gas flame of suflicient size and heat adjacent the pulverized fuel burner opening to ignite the fuel when the heating system is to be started in operation. Although illuminating gas is preferable for this purpose, it should be understood that any other suitable inflammable fluid may be used, if desired.

The pulverizing apparatus, the feeding mechanism therefor, and the mixing and feeding fan are shown in sectional elevation in Fig. 2. The pulverizer includes certain improvements on that disclosed in the prior Patent No. 1,855,171, granted April 19, 1932, on an improv'ementin unit pulverizers; and while'this pulverizer is described in connection with an, automatic heating system as applied to .the pulverization of coal,'it will be understood that the pulverizer may be used equally as well for the pulverization of 'materials other than coal, which materials may be of a highly diversified character. In other words, the

pulverizing apparatus represented by the present improved construction is of a very wide and general utility, and by no means restricted to the specific use or adaptation thereof, in connection with a heating system as will be described herein, merely for the purpose of illustrative convenience.

. As shown in Fig; 2, a hopper 23 is provided to receive the material to be pulverized, which material in the illustrative embodiment of the apparatus is coal which is adapted to be burned at the annular burner opening II, this coal being delivered to the said burner opening in a finely powdered condition, the comminution thereof being accomplished in the mill structure now about to be described in detail. It will be understood, however, as has been previously pointed out, that any material of a suflicient degree of softness may be comminuted in the pulverizing apparatus.

In this pulverizing apparatus, as illustrated in Fig. 2, a rotary feeder 24 is mounted in the throat 25 above the feeder discharge outlet 26. The throat 25 is attached to a plate 21 mounted on the top of a casing 2-8 in which the pulverizer 29 and the fan 30 are enclosed. The casing 28 is supported on the bed plate or base 3| which also supports the motor 32 for driving the fan shaft 33. The inner end of the shaft 33 carries the fan side rotor element 35 of the pulverizer 29.

The feeder 24 comprises a rotary element 36 mounted on the shaft 31. A plate 36 pivoted at 39 rests loosely on top of the rotary element 36. The plate 40 is yieldingly supported by the roller 42 pivoted to the inner upper end of the slide rod 43.

The rod 43 slides through a wall of the throat 25 and also through a strap '44 secured to the bracket plate 45. A nut 46, screw-threaded onto the rod 43, acts as an adjustable abutment to limit the inward movement of the roller 42. A spring 41 between the nut 46 and the stationary strap 44 is compressed when the material fed below the feed roll 36 depresses the plate 48.

A permanent magnet 48 fastened to a removable cover 49 is placed in the path of the descending material to remove tramp iron. Such permanent magnet and the feeding apparatus adjacent the same, as shown in Fig.2, may be the same in construction and operation as that disclosed in the aforesaid Holbeck Patent No. 1,855,171, granted April 19, 1932. If desired, an electromagnet 50, as shown in Figs. 8 and 9, may be substituted for the permanent magnet 48 and arranged to be energized whenever the feeding mechanism 24 is' operated.

A hollow circular closure 5| for the feed side of the casing 28 is provided with a platform 52 10 on which is mounted the motor 53. The shaft 54 of the latter extends inwardly and carries at its inner end the feed side rotor element 55, which is shown in section in Fig. 2 and in perspective in Fig. 5. When the motor 53 is operated, the rotor 1 55 is rotated relatively to the casing 28 and the closure 5| in a direction opposite to the direction of rotation of the fan side rotor element 35 which is driven by the motor 32. The fan side rotor element 35 is shown in perspective in Figs. 3a 20 and 4.

The feed side rotor element 55 together with the closure 5| and the motor 53 may be moved axially .of the shaft 54 away from the casing 28 and then swung laterally on vertical hinges so as that both rotors will be freely accessible for inspection, repair or replacement. The bracket 56 hinges 51, 51 to the outer front side of the casing 28. To the vertical hinges 58, 58 on the outer 30;

edge of the bracket 56 are pivoted rearwardly extending links, the inner ends of which are pivoted by means of the vertical hinges 59, 53 to the outer face of the closure 5|, as shown in Fig. 2. The bracket 56 and the links serve to support the .3 motor 53, the closure 5| and the rotor 55 for bodily movement as a unit, first axially of the shaft 54 and then arcuately. The reverse movement enables the closure 5| to be brought back into interfitting relation with the casing 28, as shown in 4 Fig. 2. This supporting structure is disclosed in the prior Holbeck patent No. 1,855,171, granted April 19, 1932. v

- By referring to Fig. 2, it will be seen that the closure 5| when in the position shown, provides a 45 opening 63 through the central portion of the fan 50 side rotor element 35. A removable cylindrical liner 64 is provided with circumferentially spaced projections 65 which extend transversely parallel to the axis of the shafts 33 and 54. The inner cylindrical wall of the liner 64 is provided with a 55 multiplicity of transverse grooves to form a serrated inner cylindrical grinding wall 66 closely adjacent to which the radial-grinding lugs 61 and 68 on the rotors, travel' along circumferential paths. Circular shoulders or supporting sur 60 faces are provided on the annular flanges 69 and 18 for engagement by the radial projections 65 to center the liner 64 or hold the same concentric with the axis of the shafts 33 and 54'. The circumferentially distributed points of support at 65 65, 65 lessens the frictional contact to facilitate removal of the liner when desired, but nevertheless the frictional mounting of the liner is sufficient to hold the same in adjusted position against the partition 6| at its rear edge and 70 against the inner edge of the closure 5| at its front edge.

When the coal to be pulverized falls to the bottom of the chamber 68, it will accumulate to a certain extent therein. If there is any tramp 75 iron or other uncrushable material, the larger pieces of the material will remain in the bottom of the chamber 60 and may be removed when the closure 5| is opened.

Inasmuch as the disk 55 is closed, the material to be pulverized must find its way peripherally of the disk 55 between the grinding lugs 68 into the pulverizing zone. During such passage, the material is ground by impact against the leading sides of the lugs 68 and against the serratedcylindrical wall 66.

The fan 30 driven by the motor 32 is adapted to produce a current of air from the feed side of the disk 55 into the hollow chamber between the rotor elements 35 and 55.. Whatever material passes through the peripheral space surrounding the rotor 35 will be further crushed by impact against the radial spaced lugs 61, 61, and by being thrown by the latter against the serrated cylindrical wall 66.

While the suction of the-air through the opening 62 tends to draw the crushed material through the peripheral space between the lugs 61 and the serrated wall 66 and radially to the left of the rotor 35 as viewed in Fig. 2, this tendency is counteracted by the radial fins 15,15 which are formed in radial continuation of the spider arms 16, "I6, and by the auxiliary radial fins I1, 11 intermediate the fins I5, I5 as shown in Fig. 3. The faces of the fins I5 and 11 adjacent to the inner wall of the partition 6| are approximately in the same vertical plane which is closely adjacent to such inner wall. Consequently, an effective seal will be produced to prevent the passage of coarse material between the back of the rotor 35 and the adjacent wall of the partition 6|.

The rotor 55 is provided with parallel spacedapart pulverizing lugs 68, 68, which may be integral with'the grinding lugs I8, I8, but the spacing between the latter is shorter than the spacing between the grinding lugs 68, 68. The rotor 35 is provided with similarly spaced pulverizing lugs I9, I9, which overlap the lugs 18, I8 so as to leave only a small cylindrical space 80 between the path of travel of the adjacent faces. It is preferred to arrange the parallel lugs 18 and 19 so that the-path of travel of the feed side rotor pulverizing lugs 18 shall be of smaller diameter than the path of travel ofthe fan side rotor pulverizing lugs. I9. This arrangement enables thegrinding lugs 68 to be placed adjacent to the serrated wall 66 while providing sufficient space between the lugs 68 for entrance of the material into the pulverizing zone, and, moreover, the entrance to the ring spacebetween the paths of travel of the adjacent faces of the pulverizing lugs 18 and 19 will be nearer the lug 68 to lessen the tendency of the material to pass back to the rotor 35 and the adjacent wall of the partition 6|. It should be understood that the rotors are driven at high speed in opposite directions and that the lugs 18 and I9 of the rotors cooperate with each other and v'ih the serrated wall 66 to pulverize the material. During this pulverizing action, the particles of material are acted upon by centrifugal force which tends to throw or hold them outwardly in opposition to the inward air current produced by the fan 30 and, as the result of these forces and instrumentalities acting on the particles, only the finely pulverized material is carried by the air current through the opening connected by a belt 82' to a pulley 82 which is mounted loosely on the shaft 85 of the speed reducer 86. The shaft 81 of the latter is connected to a disk 88 shown in Fig. 1. n the shaft 31 of the feed roll 36 is mounted an arm 89 which is pivotally connected to a link 90. The latter is adjustably connected to a diametrical slot M on the disk 88.

A clutch 92 which is adapted to be spring released is associated with the pulley 82", the outer clutch element 93 being splined on the shaft 85. An electromagnet 94 mounted on the bracket 95 secured to the hopper 23 may be employed to pull the rod 96 to the right as viewed in Fig. 2, thereby swinging the lever 91 on its pivot 98 to apply the clutch 92 and thus connect the shaft 33 to the. speed reducer 86. The lower end of the lever 91 is pivotally supported on the bracket 99 secured to the fan housing 28. A shipper I00 connects the lever 91 to the clutch element 93. the shaft 33 rotates at a high speed, the speed reducer 86 will effect relatively very slow opera: tion of the feeding mechanism 24.

On account of the high speed rotation of the shaft 33 and the parts connected thereto includ- 5 ing the armature of the motor 32, there will be considerable momentum'tending to continue rotation of the shaft 33 after the current to the motor 32 has been cut off. It is desirable to stop the feeding mechanism in the automatic heating system illustrated in Fig. 1 as soon as the current to the motor'32 is cut off and therefore the electromagnet 94 is arranged to be ole-energized so that the clutch 92 will be released and the feed mechanism 24 stopped as soon as the motor current is interrupted.

In order to assure the mixture of an ample amount of air with the pulverized coal enteringv the fan chamber 8|, it is preferred to provide an air intake opening at IOI regulated by a shutter I02 operable by the handle I03. The mixture of air and the pulverized coal is forced by the blower fan 30 through the discharge pipe I04 into the pipe I5 for passage to and through the burner I2. If desired, the connection of the pipe I5 may be eccentrically of the cylinder I3 so as to effect a spiral flow of the mixture through the annular cylindrical passageway in the burner to maintain thorough mixture and a uniform distribution of the pulverized coal as it enters into the furnace chamber II.

The wiring diagram of the circuits and the connections for the system of control is shown in Fig.

7. A hot water temperature switch or steam or vapor pressure shown is illustrated diagrammatically at I05, a low water switch at I06, a room thermostat switch at I01, a time or clock switch at I08, a manual switch at I09, and a stack switch at IIO. These switches may be of well-known construction and those designated I05, I06, I01 0 and H0 are automatically tiltabie mercury tube switches of well-known construction. 7

When the main line switch III is closed an the manual switch I09 is closed, the switches I05, I06 and I I0 are normally closed. The room ther- 5 mostat switch is open when the heating system is out of operation. When the thermostat switch I01 closes to start the heating system, a circuit is completed from the supply main II2 through the conductor II3, switches I05, I06, I01, I09, safety switches H4, H5, conductor H6, and solenoid I I] to another supply main I I8. The energization of the solenoid III effects lifting of the armature II9 to close the motor switch I20.

By means of the separate manual switches I22,

Although 20.

I23, the motors 53 and 32 are connected to the conductors II2', I2I and H8, and the latter are connected to the supply mains when the switch I20 is closed. Suitable starting apparatus not shown may be provided for the motors 32 and 53.

Heating resistances I24, I24 and I25, I25 are associated with the safety switches H4 and H5 to open the circuit to the solenoid II I if excessive currents flow through the motors 32 and 53. Each of the safety switches comprises an element which will be warped sufficiently by a predetermined amount of heat to open its switch. Opening of either switch will effect opening of the 53. Simultaneously with the starting of the motors 32 and 53 by the closure of the switch I20, the electromagnet 94 will be energized to effect application of the clutch 92, as shown in Figs. 2 and 7.

Also, as soon as the switch I20 closes, the solenoid 2| will be energized by the current in the conductor I26 and consequently the electromagnetic valve 2| will be opened to produce the expansion gas flame for ignition of the mixture of pulverized coal and air distributed to the burner I2 by the fan blower 30. Such expansion gas flame will continue until the furnace has been thoroughly heated because the stack switch I I is placed in the flue I2'I at a point remote from the burner I 2. The arrangement is therefore such that, although the expansion gas flame continues only during the starting period of the heating system, the length of such period is indefinite, since it is dependent upon the desired heating up of the furnace to the point where the burner I2 for the pulverized coal will be self-sustaining. That is to say,the adjustment of the stack switch H0 and its location, shall be such as to continue the expansion gas flame to maintain the burning of the pulverized coal at the burner I2 until sumcient heat is generated in the furnace to render the burner I2 self-sustaining while the pulverized coal is fed into the furnace and the electromagnetic valve has been closed by the t0 the metal block I29, while the other terminal I30 is insulated and connected to the conductor I3I. The transformer I32 is connected in parallel with the electromagnet solenoid 2 I, as shown in Fig. 9. Simultaneously with the opening of the electromagnetic valve 2 I, the electric ignition mechanism is operated to ignite the gas flowing from the pipe I9 and the gas flame thus produced will continue until the stack switch opens the mercury switch I I0 automatically, whereupon the operation of the ignition mechanism will be discontinued, the gas flame will be extinguished, and the pulverized coal flame will sustain itself in the furnace chamber until the opening of the room thermostatic switch I0'I will effect automatic stopping of the motors 32 and 53 and extinguishment of the pulverized fuel flame.

In order to assure sufficient air being supplied to the pulverized coal burner I2 when connected to the largest furnaces, an auxiliary blower I33 operated by a motor I34 may be connected by switch I20 and the stopping of the motors 32 and the pipe I35 to the mixing chamber I30, which is associated with the pipe I5, as shown in Fig. 8. The motor I34 is connected to the conductor I I2,

I I8, and I2 I by the manual switch I31, as shown in Fig. 9. Therefore, whenever the motors 32 5 and 53 are operated, the motor I34 is also operated. The three motors 32, 53 and I34 are started and stopped simultaneously.

In the system shown in Fig. 8, a separate motor I38 is provided to drive the feeding mechanism 10 24 through the speed reducing mechanism shown in Fig. 2, thereby eliminating the clutch apparatus shown in the latter view.

As shown in Fig. 9, when the manual switch I39 is closed, the motor I 38 will be connected by the conductors I40, I4I, I42 to the terminals of the motor 32. The motors 32 and I38 are connected in parallel so that whenever one-is operated the other one also will be operated. The use of'the separate motor I38, however, enables the feed mechanism 24 to be stopped by the cutting off of current from the motor I38 indepentently of the motor 32. The stopping of the feed mechanism is therefore independent of the stopping of the parts connected to the fan blower mo- 25 tor 32. The speed reducing mechanism has sufficient friction to stop the motor I38 as soon as the current thereto is interrupted, although, if desired, an electromagnetic brake may be used for the motor I38. It should be particularly understood that when the current to the motors 32 and 53 is cut off, they immediately begin to slow down, the pulverizer and the blower cease to function sufliciently, and therefore the feed of coal into the chamber 60 should be discontinued 35 when the current to the motors 32 and 53 is interrupted.

Only when the feed motor I38 is operated is the electromagnet 50 energized, thus economizing current, because only when the feed mechanism 40 24 is operated need the tramp iron magnet be operative. If, during operation of the pulverized fuel burner the pressure in the case of a steam boiler reaches a predetermined maximum, or when the heating of the hot water in a hot water boiler reaches a predetermined temperature, the switch I05 will open to automatically stop the operation of the burner I2. When the steam pressure or temperature has dropped sufliciently, the direct firing unit will be automatically restarted. In a similar manner, when the water in the boiler falls below a predetermined minimum, the switch I06 will be opened to prevent further operation of the system until the proper water level has been restored. The time switch I 08 operates automatically to start and-stop the direct firing unit at predetermined set times.

It will be understood, in connection with the electric ignition apparatus, that it is not to be limited to the use of gas only for ignition, as fuel oil, gasoline, or other inflammable liquids may be used in a similar manner, if desired.

, Reverting to the operation of the pulverizer comprising the oppositely rotating elements 35 and 55, it should be noted that the construction is such as to maintain the same entirely open at all times for free and uniform flow of air during pulverization. The coal to be pulverized is fed gradually into the chamber 60 from which it passes peripherally of the disk of the rotor 55 into the ring space 80. The feed side lugs 08 and I8 keep the coal from accumulating at any portion of the wall 60 of the liner 64, so as to permit free passage of the air and coal into the ring space 80 between the lugs I8 and I9. The

outer ends of the lugs 68 are closely adjacent to elements having overlapping lugs in the pulverthe serrated wall 66, and therefore the pulverizing action on the material may start before such material reaches the oppositely moving lugs I8, 19.

The radially projecting lugs 61 closely adjacent to the serrated wall 66 act to keep the space surrounding tHe lugs 18 open for'free access to the air through these lugs into the chamber between the rotor elements. Air may pass through the spaces between the lugs 19 as well as between the spaces between the lugs 18 into the chamber 29, but coarse particles are ejected outwardly against the wall 66. When the particles enter the space 80 they are pulverized by impact and attrition eifected by the rapidly rotating lugs i8, 19 passing each other in opposite directions.

The radial ribs or fins 15, H, in addition'to strengthening the fan side rotor element 19, also seal the space between the back of such rotor element and the adjacent Wall of the partition Bi against the passage of any coarse'particles through such space to the opening 62. Such ribs or fins set up a fan action counteracting the tendency of the fan 30 to produce a current of air through such space. The air entering the pulverizing zone is therefore prevented from being by-passed into the fan housing without going through the lugs 18 and 79 of the rotors.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I wish therefore not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. Bulverizing apparatus comprising the combination with a'casing, of two overlapping con-- centric rotor elements comprising spaced-apart series of pulverizing lugs parallel to the axis of rotation of the said rotor elements, separate mtors one connected to each of said rotor elements to rotate the same in opposite directions, means affording an entry opening into the said casing for the material to be pulverized, peripheral spaced-apart preliminary grinding devices on the rotor.element adjacent to the said entry opening, a cylindrical grinding wall adjacent to the path of the said preliminary grinding devices, the rotor element adjacent to the entry opening comprising a closing disc compelling the material to pass peripherally of the said last-named rotor element to the said pulverizing lugs, spacedapart peripheral grinding devices adjacent to the'said grinding'wall and mounted on the rotor element spaced from the entry opening, the said last-named rotor element having an exit opening in the central portion thereof, and adial ribs on the open rotor element adjacent to stationary inner wall of the casing to prevent bypassing material from between the rotor elements to the opening in the spaced rotor element.

2. Pulverizing apparatus comprising the combination with a casing having a single pulverizing vzone, of pulverizing rotor elements, one comprising a closed disc on the entry side of the casing and the other being open'at its central portion at the outlet side of the casing, the said rotor relation to the said cylindrical grinding wall, a

fan to produce a current of air through the said zone from the peripheryof the said zone through the opening in the said open rotor element, radial ribs on the back of the said open rotor element in position to move adjacent to an inner wall extending transversely of the said cylindrical wall, and'me'ans for driving the said rotor elements in opposite directions.

3. A pulverizing apparatus comprising the combination with a casing defining a pulverizing zone therein, of pulverizing means within the casing, instrumentalities including rotary feed devices for feeding material to the pulverizing means, mechanism including a motor for driving the pulverizing" means, means for driving the 20 said rotary feed devices from the mechanism for driving the pulverizing means, and instrumentalities associated with the driving means and in- Ucluding clutch and magnet devices for stopping the actuation of the feed devices simultaneously with a stopping .of actuation of the mechanism for driving the pulverizing means and independently of continued movement of the latter mechanism after power shut-off therefrom. p 4. A pulverizing apparatus comprising the combination with a casing defining a pulverizing zone therein, of rotary pulverizers within the pulverizing zone, motor operated drives for the pulverizers, feeding mechanism for feeding material to be pulverized into the pulverizing zone, a clutchcontrolled driving connection between one of the motor-operated drives and the feeding mechanism for operating the latter, and mechanism for operating the clutch-controlled driving connection and including a solenoid, a. pivotally mounted lever connected to the solenoid and to the clutch of the clutch-controlled driving connection, whereby upon energization of the solenoid responsively to application of power to the motor-operated drives, the clutch becomes applied to operate the feeding mechanism, and upon de-energizing the solenoid responsively to interrupting the power to the motor-operated drives, the clutch becomes disengagedto immediately stop the feeding mechanism regardless of continued operation of the motor drives through their own momentum.

5. A pulverizing apparatus comprising the combination with a casing defining a pulverizing zone therein, of pulverizing means within the pulverizing zone, motors for operating the pulverizing means, mechanism for feeding; material to be pulverized into the pulverizing ,he, and means ans'rm A. HOLBECK.

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