US2941677A

US2941677A - Tank loading and unloading device

Info

Publication number: US2941677A
Application number: US745217A
Authority: US
Inventors: Korber Eugene
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-06-27
Filing date: 1958-06-27
Publication date: 1960-06-21
Anticipated expiration: 1977-06-21

Description

June 21, 1960 Filed June 27, 1958 E. KORBER TANK LOADING AND UNLOADING DEVICE 8 Sheets-Sheet 1 June 21, 1960 E. KORBER 2,941,677

TANK LOADING AND UNLOADING DEVICE Filed June 27, 1958 8 Sheets-Sheet 2 l A Y ,4 770R IVE June 21, 1960 E. KORBER 2,941,677

TANK LOADING AND UNLOADING DEVICE Filed June 2'7, 1958 8 Sheets-Sheet 3 62 //v VE/V ram 4770B NEYS June 21, 1960 E. KORBER TANK LOADING AND UNLOADING DEVICE 8 Sheets-Sheet 4 Filed June 27, 1958 //v Vin/rag [U6 ENE KORBER BY- My June 21, 1960 E. KORBER TANK LOADING AND UNLOADING DEVICE 8 Sheets-Sheet 5 Filed June 27, 1958 Away/70,2 5065M. Kan/5E2 $61,)! {E J1me 0 E. KORBER 2,941,677

TANK LOADING AND UNLOADING DEVICE Filed June 27, 1958 8 Sheets-Sheet 6 A7702 NE rs.

June 21, 1960 E. 'KORBER TANK LOADING AND UNLOADING DEVICE 8 Sheets-Sheet 7 Filed June 27, 1958 4 rrom/s-rs,

June 21, 1960 Filed June 27. 1958 E. KORBER TANK LOADING AND UNLOADING DEVICE a Sheets- Sheet a 93 IUIII BYWIQW United States Patent TANK LOADING AND UNLOADING DEVICE Eugene Korber, 33 Dundas St., Wallaceburg, Ontario, Canada Filed June 27, 1958, Ser. No. 745,217

7 Claims. (Cl. 214-17) This invention relates to apparatus for unloading grain or other comminuted material from storage tanks, especially when the material has become compacted or both compacted and agglutinated.

A number of materials such as alfalfa or grains and the like when processed and put into storage tanks in large quantities become compacted and agglutinated; others, even when in the natural state, exude under pressure a viscous fluid which tends to agglutinate the mass of material. In these circumstances the stored material will not flow and cannot therefore be removed merely by opening an orifice in the bottom of the tank. Grains under the pressure exerted upon the lower stratas in a tank compact sufiiciently such that even though some of it may flow, so called bridging will occur and the flowceases. Moreover a certain amount of free flowing substances will remain in large tanks because of the angle at which the material in question will remain at rest in a conical pile. It follows that when any one or more of these factors is present, it becomes desirable, and often necessary, to use a mechanical apparatus or manual labour to move the material to the point of exit from the tank in which it is contained.

Further usefulness of this invention arises because present day storage methods permit harvesting when the crops are in their prime. In the case of alfalfa and the like, which are comminuted, the end product when stored in tanks would under ordinary circumstances sour or decompose. To prevent this occurring such materials are now stored in the presence of an inert gas which is maintained above atmospheric pressure. The gas permeates the mass and retains it substantially in the same condition that it was when introduced into storage. However, considerable diificulty arises when the material in the tank is to be removed and the tank is vented to permit escape of the gas. It has been found that even though the tank remains open for a period of days a portion of the gas remains trapped within the material, and this, when loosened, permits such pocketed gas to escape. Because of this hazard of asphyxiation manual labourers cannot be put into the tank to loosen the material and guide it toward an outlet orifice.

To provide the requisite loosening and moving action various devices have been proposed before the present invention but they have not proved adequate to overcome all difiiculties met with when removing from a tank material of the type described. This is so because of the wide variations in compactness and agglutination that may be encountered by any one device, and the consequent wide range and precision of control that is required for a mechanical unloading device of this type to operate satisfactorily. When material has been held for a few days or even a few months it is comparatively easy to loosen and advance to the discharge port. In such circumstances the rate of loosening and discharge can be too great for the apparatus to handle with the result that it becomes overloaded, jammed, and refuses to operate.

On the other. hand when the material has been. held in.

' in accordance with this invention.

storage for over a longer period of time, such as ayear or more, the material may have become very compact and often it not only becomes compacted but also agglutinated. The density of the mass of material within, the tank varies from top to bottom. A tank of fifty to sixty feet in diameter and in the neighbourhood of thirty feet in height contains between eight and nine hundred tons of material so that the pressure upon the material at different depths increases considerably. Under these circumstances many of the prior devices failed because the sweep advances too rapidly. In lightly compacted material it became choked and stalled. In the more densely packed material the depth of cut was too great and the apparatus ceased to function. Finally, the sweep blades used in prior devices to cut and deliver the material to,-

the exit orifice have not in general been of the shape required to yield a uniform quantity of output at a steady rate of speed.

I have found that many of the disadvantages of prior devices of this nature can be overcome and improved operation secured by an unloading device constructed the material is stored is provided with a central vertical shaft extending vertically through the top of the tank at the centre thereof and having a cable winding means rigidly attached near its lower end inside the tank. A sweep assembly including a support frame is suspended in a horizontal plane inside the tank by means of a series of cables attached to it at equal intervals around the periphery of the support frame, and extending upwardly adjacent the tank wall to engage with pulleys mounted;

in appropriate positions at the top of the tank. The cables then extend radially inwards towards the cable winding means, to which they are attached in such man-. ner that all the cables have a substantially equal amount of lap around the respective sheaves, and as the drumis turned, the eifective winding diameter (which changes because the successive turns of each cable align themselves in the same plane) is maintained equal for all cables. On the bottom of the supporting frame is a sweep carriage rotatably mounted, preferably by means of rollers, so as to allow the sweep carriage to rotate relative to the supporting frame, in concentric relation to it.. Mounted on the sweep carriage are sweep blades, preferably in the form of a logarithmic spiral so as to obtain, substantially constant scraping action on the material in the tank throughout their entire length. A first drive unit, mounted on the top of the tank and rigidly connected to the shaft, provides steady, slow rotational movement to the cable sheaves, thereby causing the sweep assembly to move vertically while at the same time maintaining it in a substantially horizontal plane. A second drive unit is mounted on the supporting frame inside the tank, and causes the rotational movement of the sweep carriage. Finally, in a preferred embodiment of my invention I provide a system of counterweights to counteract part of the weight of the sweep assembly, thereby appreciably reducing the power consumed by the first drive unit. When the counterweights are used it may indeed be advantageous to utilise another embodiment of the first drive unit wherein the torque required to turn the central vertical shaft is applied through the counter: weight cables.

It is thus an object of the present invention to provide an apparatus that can be used gradually to loosen and. advance a quantity of material stored in a tank, the rate of advance and the precision of movement being such that the operation of the apparatus can be easily controlled to avoid overloading and clogging of the appa- 0 ratus itself or the conveying system carrying away the Patented June 21, 1960 The tank in which;

to control the depth of cut selectively between ten and thirty one-thousandths of an inch.

A still further object of the invention is to provide means to vary selectively the rate of delivery in accordance with a predetermined demand or in accordance with the requirements imposed on the system by the particular type of material being handled.

' These and other objects and advantages of the invention will become apparent as the following description of its construction and operation proceeds.

Referring to the drawings:

Figure 1 is a perspective view of a tank with the unloading apparatus mounted therein, and also showing the counterweight system which is used in one embodiment of the invention.

Figure 2 is an enlarged partial top plan view of the sweep assembly, comprising a supporting frame and a sweep carriage.

Figure 3 is a top plan view of the supporting frame;

Figure 4 is a top plan view of the sweep carriage;

Figure 5 is a sectional view taken on the line 5-5 of Figure 3 to show the manner in which the sweep carriage is rotatably suspended from the supporting frame;

Figure 6 is a top plan view of the means for rotating the sweep carriage;

Figure 7 is a sectional elevation taken on the line 77 of' Figure 2;

Figure 8 is a sectional detail of the winch drum for the suspension cables together with its mounting assembly at the top of the tank, and which also shows the conical cable Winding drum for use with the counterweight system;

Figure 9 is an enlarged detail of the cable winding drum for the suspension cables;

Figure 10 is an enlarged view of the core of the cable winding drum, showing the staggered cable entrance holes in the base of each sheave groove;

Figure 11 is an enlarged perspective of the conical cable winding drum;

Figure 12 is a front elevation of the driving mechanism for causing vertical movement of the sweep assembly;

Figure 13 is a side elevation of the driving mechanism shown in Figure 12;

Figure 14 is an enlarged view of the crank assembly designed to show the manner of adjusting the throw of the crank;

Figure 15 is a detail view of a driving dog and a-section of the driving gear;

Figure 16 is a side elevation of a modified driving mechanism used for causing vertical movement of the sweep assembly;

Figure 17 is a top plan view of a driving mechanism interconnected with the counter-weight suspension cable and Figure 18 is a view of the corer device.

Figure 1 shows in phantom outline a tank 20 which, in the example shown, is of the order of 50 to 60 feet in diameter and a height of approximately 30 feet. The tank is closed at the bottom and top by members 21 and 22 respectively. The top has formed therein a central bore 23 and a loading port 24 near the periphery of the tank. A column 25 extends upwardly from the bottom of the tank to a point adjacent the roof or top member 21 where it has secured thereon a cap which is of sufficient strength to support a frame-work 26 which carries upon it rafters 27 (see Figure 8) of the roof or top portion 21. The rafters terminate short of the central bore 23 where a well or chamber 28 is positioned and secured to the rafters 27. The wall 29 of well 28 also rests on frame-work 26 which is carried by column 25. A shaft 30 rotatably supported in bearings 31 and 32 is centrally positioned in Well or chamber 28 and extends upwardly through bore 23 and packing gland 33. A winch drum 34 is rigidly mounted upon shaft 30 intermediate portion 35 of the room (which forms pant of top 2.1) and-a floor portion'36of well 28 .4 which rests. on frame-work 26. The winch drum 34, as shown in Figure 9, is of the multiple sheave-type, here shown as a twelve groove drum. The width of the grooves is selected so that only one thickness of the cable used in conjunction with the sheaves can be accommodated in each groove, thereby forcing each turn of the cable, as it is wound on the drum, to align itself in the same plane as the previous turn so that the effective winding diameter of the drum is uniformly increased by twice the thickness of the cable each time the drum revolves.

A series of cables 38, twelve in number, are each secured at one end to winch drum 34 by passing a free end of the cable into one of the grooves 39 thence through a bore 40 (see Figure 10) into the recessed bore 41 of the drum core 42, the recess allowing cables 38 to pass upwardly in the bore 41 without interfering with shaft 30, and thence outwardly through one of the windows 43 formed in the upper portion of the drum core 42. The end is then fastened to one of the flanges 44 secured to the drum 34 by threading it through a hole 45 and back again through a hole 46 where it is anchored, by splicing or clamping to the standing portion 47 of the cable 38 (see Figure 9). The bores 40 formed in the base of the respective grooves forming the sheave on cable winding drum 34 are spaced equidistant circumferentially around the drum, one such bore being located in the bottom of each groove the arrangement being such that when cables 38 extend radially outwards from the drum 34 at equal intervals around its periphery, each cable 38 will have an equal amount of lap on drum 34.

As best shown in Figure 1, cables 38 extend radially outward from the cable winding drum 34 so as to define substantially equal angles between them, and then pass over pulleys 48 which are secured to the underside of roof 21. adjacent the tank wall. The-cables depend downwardly from the pulleys 48 and are attached at their free ends to lugs 49 (best shown in Figure 5) which are secured to a supporting frame 50 at equally spaced intervals adjacent its periphery (see Figures 2 and 5). The supporting frame 50 shown in semi-top plan view in Figure 2 and in full top plan view in Figure 3 consists of twelve truss-like members 51 which are each secured at their respective ends 52 and 53 to junction plates 54 to form a twelve sided polygon shown in Figure 3.

Rotatably mounted upon each junction plate 54 in suitable bearings 55 is a shaft 56, as best shown in Figure 5. The lower end of shaft 56 protrudes below the junction plate 54. Rigidly secured to the protruding end of shaft 56 is a circular bearing plate 57 having a bevelled traction surface adaptedto support and engage with driving rim of sweep-carriage 58 so as to allow sweep-carriage 58 to rotate relative to the supporting frame in a manner substantially concentric therewith.

The sweep-carriage 58 (see Figure 4) consists of a central hub 59 which is rotatably and slideably mounted on column 25. Secured to and radially extending from the hub 59 are a series of spokes 60 which are secured at their opposite ends to driving rim 61. The spokes 60 are provided with turnbuckles 62 intermediate their ends (most conveniently located near the driving rim 61 so as to facilitate adjustment) so that the hub 59 and rim 61 may be brought into concentric axial relationship and also to maintain the traction surface of the driving rim 61 in a plane normal to its axis of rotation. As is apparent from the foregoing description and the drawings sweep-carriage 50 is supported on bearing plates 57 of spaced shafts 56 by the driving rim 61 which, as best shown in Figure 5, is fabricated from angle iron stock having an L-shaped cross-section, the downwardly extending flange being used to maintain the carriage in an orbit that is concentric with the axis of column 25 (and therefore with the sweep supporting frame 50 itself). It will also be noted that the clearance between the bevelled traction surface of bearing plates 57 and the bottom edge 62 of junction plate ,54 isless thanthe perpendicular. depth. of. the, vertical flangeof driving-rim 61, thus providing means to confine to a very limited degree vertical movement of the sweepcarriage relative to the supporting frame 50 and thereby preventing disengagement or misalignment from their concentric positions.

As best shown in Figures 2 and 7 the sweep-carriage 58 is driven by the frictional engagement of the upper surface of driving rim 61 with the tread of a pneumatic rubber tyre 62 which is mounted on a wheel 63 which in turn is rigidly secured to a shaft 64. The shaft 64 is rotatably mounted in bearings 65 and 66 on a bedplate 67 which is secured to the upper surface of the carriage supporting frame 50. The shaft 64 extends beyond the bearing 65 and is coupled to a reduction gearing 68 which is driven through a shaft 69, pulley 70 which is secured thereto, belt 71, driving pulley 72 and an electric motor 73.

Referring now to Figure 4, sweep-carriage 58 has secured on its underside sweep-blades 74, in the embodiment shown three of such blades being provided. The number of these blades may be adjusted to suit the size of the installation, the type of material being handled and the required rate of delivery. As shown, the sweepblades 74 are bent in the form of substantiallylogarithmic spiral, thereby ensuring that the ploughing action is uniform throughout their length. The outermost free ends of the sweep-blades 74, adjacent the cylindrical wall of the tank 75, terminate in hooks 76 which gather and carry the loosened material which is sliced off and advanced by the sweep-blades. The material caught by hooks 76 is advanced to. a vertical shaft 77 formed in the body of the stored material adjacent the wall of the tank (see Fig. 1).

The shaft 77 is formed by pulling upwardly through the material a coring device 78 (see Figure 18) which consist-s of a cylindrical part 79 to which a ball 80* has been secured. Attached to and leading from the bail 80 is a cable 81 which, prior to loading tank 20, is releasably secured to the inner-side of the tank wall by clips. The cable 81 extends upwardly from the bottom 22 of the tank, adjacent an exit port 83 at the bottom of the tank, to the top 21 Where the free end is releasably secured in loading port 24. The coring device 78 mentioned above is placed on the bottom 22 of the tank 20 perpendicularly below a point traversed by the hooks 76 and adjacent the exit port 83. When the tank is to be unloaded the free end of the cable 81 is brought out through the access port 24 where it may be secured to a winch or other suitable means, which, when rotated winds up the cable and pulls the bail upwardly through the material within the tank. In this manner a column of material is severed and loosened, since the coring device cuts free a column of material and the bail travelling upwards severs the column into two portions and tends to loosen it.

Referring to Figure 1 there is shown positioned in exit port 83 a screw-conveyor 84 which has its inner end positioned directly under the severed column whereby when the conveyor is operated the loosened column will feed downwardly and be carried out through the port onto another conveyor 85 by which it may be fed into a truck or processing machinery. The sweep assembly S is controlled in its downward unloading operation by a drive assembly 86 which (see Figures 12 and 13) is coupled to the cable winding drive-shaft 30. The drive assembly 86 consists of a sleeve 87 which is provided with diametrically opposite grooves 88 which engage with key members 89, which are fabricated from pieces of channel ironand made integral with circular plate 90 rigidly mounted on shaft 30. The shaft 30 extends upwardly into the sleeve 87 at 91 to maintain the shaft 30 and sleeve 87 in concentric alignment. The upper end of sleeve 87 has secured thereon a boss 92 which is coupled to output shaft 93 of reduction gearing 94. The input shaft 95 of reduction gearing 94 has secured thereon a gear wheel 96. The gear wheel 96 is rotated through a small increment of a revolution by

dogs

97 and 98. As shown in Figure 15 the dog 97 is positioned in the space between the teeth with its working face abutting against the uppermost tooth 99 while the dog :98 is positioned in the space between the teeth with is working face abutting against the lowermost tooth 100. The dogs are provided with shrouds 101 which straddle the gear-wheel and which, together with the action of spring 102 connecting the shrouds, maintain the dogs in engagement with the teeth.

The

dogs

97 and 98 are adjustably mounted on

rods

103 and 104 respectively. The opposite end of the

rods

103 and 104 are each provided with an

eye member

105 and 106 respectively which are adapted to be rotatably mounted on a crank pin 107. The crank pin 107 is rigidly secured to a lever 108 which is rotatably secured at one end to a pintle 109 which is mounted eccentrically on disc 110, near the periphery thereof. The disc 110 is secured to the output shaft 111 of a reduction gearing unit 112, as best seen in Figures 12 and 13. The input shaft 113 of reduction gearing 112 is driven by a belt 114 trained over

pulleys

115 and 116, respectively mounted on shaft 113 and the armature shaft of an electric motor 117.

Referring to Figure 12 and detail Figure 14 it will be seen that the crank pin 107 is centrally located longitudinally of lever 108 and that lever 108 is also pro vided with bore 118 which is adapted to receive therein the shank of a cap-screw 119, the threaded portion of which extends beyond the face of the lever 108 into one of the threaded bores 120 formed in the disc 110. The threaded bores 120 are laid out equidistantly on an arc struck from the centre of pintle 109 and in the position of disc 110 and pintle 109 shown in Figure 14, are all located in the upper right quadrant of disc 110. This construction provides a means whereby the eccentricity of crank-pin 107 with respect to the shaft 111 may be varied by moving the lever 108 to a position wherein the bore 118 registers with any one of the bores 120 in the disc 110, after which lever 108 and the disc 110 are secured to one another by the cap-screw 119. By such means a crank with a variable throw is provided, the variation of throw in turn affecting the linear travel of

rods

103 and 104, since the latter depends on the pitch diameter on which the crank-pin 107 has been set. Finally, variation in the travel of

rods

103 and 104 obviously affects the arc through which the

dogs

97 and 98 move the gear wheel 96 each throw of the crank, the arrangement being such that the gear wheel 96 will rotate through an are substantially equal to the perpendicular linear travel of the crank-pin 107. The arrangement as a whole thus permits variation in the rate at which the sweep assembly unit is raised or lowered'through the winding of cables 38 on drum 34.

In the drive mechanism just described, the unit itself sits on and is supported by shaft 30, the bottom end of sleeve 87' resting against the upper surface of circular plate 90, and the grooves 88 engaging key members thereto. It is obvious that in the absence of some connection between a stationary part of the drive mechanism and the tank that the former would tend to rotate about shaft 30, rather than imparting motion to it. To overcome this tendency one end of arm 121 (see Figure 13) is.attached to some stationary part of the drive mechanism (here shown as part of the housing for reduction gearing 94), the other end (not shown) being rigidly connected to the tank at some convenient point.

One important advantage of having the drive mecha nism sit on top of shaft 30 is that merely by loosening arm 121 the whole unit can be removed from the tank and placed in operative position on the shaft 30 of some other tank. It is thus possible for one drive unit to be used for the unloading operation in a number of tanks. When the drive unit is removed from shaft 30 there will c'earse be a tendenc for the shaft to spin round sn fanow the sweep' assembly to fall until it rests onthe material in the tank, or the bottom if the tank is empty. To prevent this a lock 122 can be mounted on the end of one of the key members 89 as shown in Figure 13. The lock 122 has a vertically slideable member 123 which, when lowered in position as shown, can be adapted to engage against a stop member rigidly mounted on the top of the tank, thereby preventing rotation of shaft 30.

In Figure 16 a modified drive unit for controlling the descent of the sweep assembly is shown. The drive comprises 'the above mentioned motor 117,

pulleys

115 and 116, belt 114 and

reduction gearing

94 and 112. The sleeve 87 is removed from the shaft 30 and the output-shaft 93 of reduction-gearing 94. The drive assembly is removed'to a position a'short distance from the shaft 30 and

sprockets

124, 125 and 126 are secured to shaft 30; A'roller-chain 127 interconnects one of the

sprockets

124, 125 and 126 mounted on output shaft93 of reduction gearing 94. to one of the

sprockets

128, 129 or 130 mounted on shaft 93. The combination of the variable crank-throw and the variable ratios of the above mentioned gearing provides a sweep control suitable to remove either, a densely or loosely packed substance and permit wide variation in the quantity ofmaterial fed to the conveyor. Similarly to the drive unit shown in Figures 12 and 13, one end of arm 121 is attached to the reduction gearing housing 94 the other end being rigidly attached to some convenient place on the tank so as to prevent rotation of the unit on shaft 93.

c The drive assemblies shown in Figures 12, 13 and "16 described above provide an accurate and even control for the vertical movement of the sweep-assembly S which advances the sweep blades into the stored material at a rate of a few thousandths of an inch per revolution in a substantially steadily descending helix so that a steady stream of loosened material is fed onto the conveyor.

I In'some applications, particularly those for large installations, it may be desirable to provide counterweights on each side of the tank which have a reciprocal action with the sweep assembly, thereby making possible an appreciable reduction in the power input required to rotatethe winch drum 34. Such an arrangement is shown in Figure 17 as applied to an installation using either of the drive mechanisms described above. Immediately below plate 90 a conical'cable receiving drum 131 is mounted on shaft 30, with its smaller end at the top. As UCSlQ'ShOWll in Figures 1 and 11, the drum 131 is in the form of a truncated cone with its base 132 placed adjacent the top 21 of tank 20. A series of bar-like members 133 are secured to the base 132 and extend and converge in an upward direction where they are secured to a central hub 134. The hub 134 above the upper ends of the bar-like members 133 is capped by an annular disc 90 which surrounds the shaft'3tl to provide a flange which preventssthe cables 135 and 136 from travelling beyond the top of the truncated cone. The bar-like members 133 are secured intermediate their ends to spaced annular reinforcing rings 137 and 138 respectively.

Referring now to Figures 1 and 17 two

booms

139 and 140 aresmounted on opposite sides of the tank on substantially the same diameter, with their outer ends raised slightly and "overhanging the edge of the tank. Pulleys 140' and 141 are mounted in the end of the

respective booms

139 and 140, the rotational axis of the pulley being "substantially parallel with the top of the tank and perpendicular to the diameter on which the booms are located.

Cablm

142 and 143 are attached to drum 131 near its base '132 and lapped around the drum in such manner that both cables will simultaneously wind on or off the "drum as the casemay be, cable 142 leaving the drum and extending outwardly to pulley 140 while cable 143 ext'endsoutwardly to pulley. 141. Both cables change direction at the pulleys, so as to extend downwardly,

parallel sprockets

128, 129 and 130.

131 as before.

with the sides of the tank, and have attached att-heir lower ends counterweights 144 and 145 respectively. p v The conical shape of drum 131 is designed to equalize the torque exerted on shaft 30 for all positions of the counterweights and sweep assembly. As a consideration of the drum 34, and cables 38 arrangement easilysh'ows, each revolution of the drum 34 will increase its effective winding diameter by an amount equal to twice the't-h'ickness of the cable 38. This in turn increases the reaction torque imposed on shaft 30, and, consequently, the torque which must be exerted by the counterweight system to counteract'it. When the sweep assembly is at the taper the tank, and the sheaves on drum 34 are full of cable 38, the torque exerted on shaft 34 is obviously considerably greater than when the sweep assembly approaches the bottom of the tank and most of the convolutions of cables 38 are wound oh the sheaves. Hence when the counterweights arenear the bottom of theirtravel (corresponding with the sweep assembly being at the top of the tank) the cables will wind on the bottom, larger diameter of drum 131, so as to equalize the high torque caused by the'full sheaves on drum 34. Conversely, when the sweep assembly is nearthe bottom of the tank, and the effective winding diameter on the sheaves of drum 34 is relatively small, the counterweights will be drawn up to the top of the tank,

cables

142 and 143 being fully wound upon drum 131. This means thatthe conical surface of drum 131 will be almost completely filled with therespective cables and that they extend outwardly from the drum near its top, thus effecting a corresponding reduction in the torque exerted on shaft 30 by the counterweights. Thus the conical drum 13-1 brings about automatic compensation for the variations in torque exerted on shaft 30 caused by changes in effective winding diameter ofthe sheaves on drum 34.

Reference will now be made to Figure 17 wherein there is shown a modified drive unit for controlling the descent of the sweep assembly. This particular mechanism'is'designed for use with an embodiment of the invention having counterweights as described above. Shortly stated, "the power for controlling the gradual descent of the sweep assembly is applied to one of the

counterweight cables

142 or 143, rather than by means of a direct connection to shaft 30 as shown in Figures 12 and :13, or a sprocket and chain arrangement as in Figure 16. In the present case the drive is mounted on the top 21 of tank 20 adjacent one edge. The output shaft 93 of reduction gearing 94 is positioned in a plane parallel to the top '21 of tank 20. The shaft 93 has secured thereon the before mentioned The roller-chain 127 interconnects one of the sprockets 128, 129 or to one of the aligned sprockets 146, 147 or 148 which are secured upon a shaft 149 which is journalled in bearings mounted upon spaced members 150 and 151 of boom 139 as described above in connection with the counterweight system. The boom 139 at its inner end (i.'e. the end nearest the centre of the tank) is secured to the top '21 oftank 20. The outer end upon which the shaft'149 is journalled projects beyond the top 21. A cable Winding drum 152, taking the place of pulley in the previous embodiment, is secured to the shaft 149 for rotation therewith between the spaced members 150 and 151. Cable 142 is lapped around the winch drum 152 intermediate its ends, the inner end of the cable extending towards the centre of tank 20 and being lapped around and secured to the bottom of conical cable winding drum Similarly, the other end of cable 142 extends downwardly to support counterweight 144. When the shaft 149, upon which winch drum 152 is mounted, is rotated counterweights 144 and will be raised or lowered according to the direction of rotation of the drive assembly.

When the direction of rotation of the drive assemblyis appropriate for raising the counterweight 144, there will be*-a,slight tendency for slackness to appear in that portion of cable 142- between drums 131 and 152. The

weight of the sweep assembly, exerted through cables '38, drum 131 and thence to drum 34 will be such as to take up the slack by means of a gradual downward movement of the sweep assembly. Since the

cables

142 and 143 are wound on drum 131 in such manner that they unwind in unison, this movement of drum 131 caused initially by the raising of counterweight 144, will also cause raising of counterweight 145. By controlling the speed of rotation of drum 152 it is thereby possible to secure an appropriate, smooth ascent of sweep assembly S and at the same time obtaining a useful counterweight action.

From the preceding description it will be obvious that all the drive units could be used for raising the sweep assembly as well as lowering it. As a practical matter however, the gear reductions used provide for such a slow, gradual descent that raising the sweep assembly merely by reversing the drive unit would be a very slow process. A special faster acting drive unit designed for raising purposes could easily be used, or, as is satisfactory in many cases, the sweep assembly can be wound up by hand.

The embodiments of the invention shown are useful not only for emptying storage tanks, but also during filling operations when it is desirable to level out the material as it is poured into the tank. In such cases a certain amount of the material is put into the tank and of course comes to rest in a conical shaped pile. The sweep assembly is then lowered and tends to level out the material. When a substantially flat upper surface has been obtained, the sweep assembly is raised up well above the surface of the material already in the tank, more material is allowed in so as to again form a conical pile, after which the levelling process brought about by the action of the sweep assembly is repeated.

What I claim as my invention is:

1. Apparatus for moving comminuted material in a storage tank comprising a tank having a rotatable shaft extending vertically through bearings mounted in the centre of the top of the tank, a winding drum having sheaves mounted near the bottom end of the shaft inside the tank, pulleys disposed around the inside periphery of the tank at the top thereof, a sweep assembly adapted to move up and down inside the tank comprising a supporting frame on the bottom of which is rotatably mounted a sweep carriage having sweep blades adapted to engage the material, cables attached to the supporting frame at equally spaced points around the periphery thereof and extending vertically upwards adjacent the walls of the tank, over the pulleys, and thence radially inwards towards the centre of the tank for engagement with the sheaves at positions such that substantially equal amounts of the cables are wound around their respective sheaves at any given angular position of the winding drum, first power means for applying torque to the upper end of the shaft so as to rotate the cable winding drum and cause vertical movement of the sweep assembly, and second power means for causing rotation of the carriage relative to the supporting frame.

2. Apparatus for moving comminuted material in a storage tank comprising a tank having a rotatable vertical shaft journalled through the top of the tank at the centre thereof, a cable winding drum having a plurality of sheaves mounted on the shaft inside the tank, a plurality of pulleys mounted inside the tank at equal intervals around the periphery of the tank at the top thereof, a sweep assembly including a supporting frame suspended in a horizontal plane inside the tank by a plurality of cables attached at equal intervals around the periphery of the supporting frame, each of said cables extending upwardly from the supporting frame, over one of said pulleys and thence radially inwards to one of said sheaves, each of said cables being threaded through a hole in the base of their respective sheaves, the angular position of said holes being staggered so as to have substantially equal amounts of cable lap on each sheave, the width of 10 I the grooves 'of said s'heaves being such as to accommodatii only one thickness of-cab1e,'a sweep carriage mounted-on the bottom of the sweep supporting frame so as to permit rotation of the sweep carriage relative toand concentric with the supporting frame, sweep blades disposed on the bottom of the sweep carriage and adapted to move the material by means of a scraping action, a first power means for causing rotation of the shaft so as to effect vertical travel of the sweep assembly, and a second power means for causing rotation of the sweep carriage.

3'. The invention as claimed in claim. 2 in which a conical cable winding drum is rigidly mounted on the shaft above ithetop of the tank, a plurality of boom members are connected to the top of the tank and extend over the edgethereof at uniform intervals, a plurality of cables attached to the larger end oftheconicalcable winding drum and extending radially outwards from the drum, over the pulleys, and thence downwardly for connection to counterweights, the arrangement being such that when the sweep assembly is at the top of the tank the counterweights are at the bottom of their travel and the counterweight cables depart tangentially from the conical cable winding drum adjacent the larger end thereof, and when the sweep assembly is at the bottom of the tank the counterweights are at the top of their travel and the counterweights depart tangentially from the conical cable winding drum adjacent the smaller end thereof.

4. The invention as claimed in claim 2 in which a conical cable winding drum is rigidly mounted on the shaft above the top of the tank, a plurality of boom members are connected to the top of the tank and extend over the edge thereof at uniform intervals, a plurality of cables attached to the larger end of the conical cable winding drum and extending radially outwards from the drum, over the pulleys, and thence downwardly for connection to counterweights, the arrangement being such that the counterweights are up at the top of their travel when the sweep assembly is at the bottom of the tank, and vice versa, and at any given position of the counterweights and the sweep assembly the counterweight cables depart tangentially from a point on the conical cable winding drum where the diameter is such that the torque exerted on the shaft by the counterweights is suflicient to overcome a substantial portion of the torque exerted on the shaft by the weight of the sweep assembly.

5. Apparatus for moving comminuted material in a storage tank having a vertical shaft extending through the top of the tank at the centre thereof and journalled therein for rotation, a first power means for causing rotation of the shaft, a cable winding drum including a plurality of sheaves mounted on the shaft inside the tank, a plurality of cables extending radially from the sheaves and defining between them substantially equal angles, an end of each cable being threaded through a hole in the base of its sheave, the angular position of the holes being staggered so as to effect equal amounts of lapping about the sheaves by the respective cables, the said cables extending over pulleys disposed at equal intervals around the inside periphery of the tank at the top thereof, and thence downwardly along the tank wall to be connected at equally spaced intervals with a supporting frame, -so as to maintain the same in a substantially horizontal plane, a sweep carriage having blades adapted to engage with and move the material by means of scraping action, said carriage rotatably mounted on the bottom of the support frame, and a second power means mounted on said support frame for causing the said carriage to rotate relative to the support frame on an axis concentric with it, so that a given point on the sweep carriage describes a vertical helical path.

6. The apparatus as in claim 5 wherein the first power means comprises a frame member on which are rigidly mounted a source of rotational power, first and second reduction gearing units, the source of rotational power awrew bcinsacen e te to he. mp t t a r d o g ri unit, the output shaft of which being rigidly connected to at. disc which in turn supports aneccentrically mounted cranlrpin, at least one rod member having at one end an eye member engaging the crank pin and at the other end a dog adapted to impart intermittent unidirectional rotation to a gear wheelmounted on the input shaft of the second reduction gearing unit, and means for rigidly connecting theoutput shaft of the second reduction gearing unit to the central vertical shaft so as to transmit rotation thereto, and an arm rigidly connecting said first power means to the tank so'a's to prevent rotation of the frame.

7. The invention as claimed in claim 5 in which the sweep carriage comprises a circular member having a 12 nected at their outer ends to the circular member, sweep blades in the form of a substantially logarithmic spiral also extending outwardly from the centralhub and connected to the circular member, rollers extending down: wardly from the supporting frame and adapted to1rotatablyengage with the underside of the horizontal flange; and the second power means is mounted on the supporting frame and comprises a source of rotative power connected to a rubber tyred wheel adapted to frictionally engage the upper surface of the horizontal flange and transmit rotary motion thereto.

References Cited in the file of this patent UNITED STATES PATENTS