CA1257301A - Vacuum loader - Google Patents

Abstract

ABSTRACT

A discharge valve assembly for a vacuum loader which receives an entrainable pulverant material or the like in which one or more adjustable weights are utilized to vary the force required to move the discharge valve plate of such assembly.

Description

~25730~

VACUUM LOADER
Backqround of the Invention Vacuum loaders are well known in the plastics molding industry and are well illustrated by prior patents such as U.S. Patents 3,309,1q6 and 3,431,026. With vacuum loaders air entrained particles of materials to be used in the molding process are conveyed from a source of material to the material reaeiving chamber of the loader by applying a vacuum to the material receiving chamber. When an appropriate amount of material has been received in the material receiving chamber, as sensed by suitable control means, the material conveying is discontinued by discontinuing the applied vacuum and there-after permitting the material in the chamber to be gravita-tionally discharged through the lower opening of the loader in open communication with the chamber. The material discharge is also controlled by opening a suitable closure member or discharge valve which valve is no mally biased into engagement with the discharge opening to close such opening. Prior vacuum loaders have been of numerous well known structures as sold by various manufacturers in the United States and various foreign countries. In such known loader structures the discharge valves have been of various structures as is well illustrated by the prior art; however, such prior discharge valves have not been as satisfactory as desired or have been of rather high cost. The structures of discharge valves which have not been entirely satisfactory is due to the effect of one or more of the conditions which exist with respect to the conveyed material such as dust, irregular configuration, low bulk density, elevated temperature and the like. Dust and low bulk density _ _ _, _ , . . . , . _ . , .. . ... . _, ~ 73~i

-2 ~
occur when very light pulverant or fine material is being .... .. ..
conveyed. Irregular configuration of material occurs primarily when regrind material is being conveyed and elevated tempera~ure material occurs when heating of the material prior to conveying to a loader is required. Prior discharge valve structures range from the older, frequently used flexible member type - see Patent 3,431,026 and the more expensive positive action plunger type - see Patent 4,200,415. A spring and center rod type discharge valve is shown in U.S. Patent 3,776,600. In addition, reed switches, micro-switches, elongated springs and magnetic fields have been utilized or contemplated in controlling the movement of discharge valves for vacuum loaders.
Brief SummarY of the Invention The present invention is to the concept of providing a discharge valve for a vacuum loader with a switch assembly, including a shaft, which shaft is movable through an arc to provide one control for the energization or deenergization of the means for applying a vacuum to a vacuum loader. Such shaft carries a-valve plate which is movable into and out of -engagement with the discharge opening of the material receivingchamber of the vacuum loader upon movement of the rotary shaft in opposite arcuate directions, respectively. In addition, the discharge valve assembly include~ a weight structure, which is selectively positionable about the central rotational axis of the shaft, to provide a selectable force which determines the force required to initiate movement of the valve plate to its open position and for rotating the valve plate into its closed position. - ~ _ ~25~730~

Thus, generally speaking, the pre~ent invention may be considered as providing in a vacuum loader for receiving granular, pulverant, fine or the like air entrainable material the improvement comprising: a material receiving hopper having an upstanding material receiving chamber portion with a lowermost material aischarge opening, a control means supported with relation to the hopper with an elongated actuating shaft member extending therefrom, the shaft member being movable between spaced first and second control positions of the control means with one of the positions being adapted to be operatively connected to means for transporting such a material to such a material receiving chamber portion, a movable valve having a closure portion and an integral elongated arm member which arm member extends transversely of the shaft member and is connected to the shaft member whereby the valve and the shaft member have conjoint movement, the closure portion being supported with relation to such hopper to close the opening with the shaft member being located in the one of the positions and the closure portion being movable out of engagement with the opening to permit material to be gravitationally discharged from the chamber portion through the opening and to move the shaft member into the other of the positions, and means carried by at least one of the members for constantly urging the closure portion towards the opening.
These and other features of this invention will be better understood in view of the following description and illustrative drawings of a presently preferred embodiment of ~257301 the invention in which:
Fig. 1 is a side elevational, partially sectional, view of a known vacuum loader installation in which the loader has a discharge valve assembly constructed in accordance with the principles of this invention;
Fig. 2 is an exploded perspective view of the discharge valve assembly of this invention and the portion of the vacuum loader to which the valve assembly is attached;
Fig. 3 is a side elevational view of the adjustable weights of this invention and the structure of the vacuum loader cooperable therewith with the adju~table weights being in a higher opening force position as compared to the illustration of Fig. 4:
Fig. 4 is similar to Fig, 3 with the adjustable weights being in a relative lower opening force position;
Fig. 5 is a cros~ sectional view of the material discharge portion of the vacuum loader of Fig. l;
Fig. 6 is a view similar to the discharge portion of Fig. 1 showing a presently preferred embodiment of the invention of this application;
Fig. 7 is a bottom plan view of the structure shown in Fig. 6;
Fig. 8 i8 an exploded side e'levational view of the adjustable components of a discharge valve assembly as shown in Fig. 6, and Fig. 9 is a side elevational view of the discharge valve assembly shown in Fig. 6 with portions thereof being 25q~01 broken away.
Fig. 1 illustrates a typical prior art structure as shown in U.S. Patent 3,273,943 in which a prior flexible throat member 18 is replaced by the new and improved discharge valve assembly 100 of this invention. Only numbers 100 or above are used to identify the structure of this invention as numbers below 100 identify the same structure as identified in Patent

3,273,943. Accordingly, Patent U.S. 3,273,943 may be referred to for a better understanding of the prior art and a structure which can incorporate the present invention. As i9 known, the material to be conveyed into the material receiving body, chamber or hopper 12 - that is, chamber portion 13 and lower frusto-conical chamber portion 14 - i9 a granular, pulverant, fine, pellet or the like material so as to be air entrainable and conveyable. The conveyed materials may be of any number of compositions as are used in the plastics molding industry. The opening and closing of the lowermost opening 15 of the hopper 12 is conrolled by the discharge valve assembly 100 which (Fig.
2) consists of a formed closure or valve plate 102 r! ~.,, ~

~` '' j . 1 ~1 _ -" ~257301 r- having a formed outwardly extending arm 104 secured to a shaft 106 of a switch 108. Valve plate 102 moves between a generally horizontal position whereat discharge opening 15 is closed and a downwardly extending position whereat opening lS is open to permit material to be gravitationally discharged from hopper 12.
As is known, plate 102 is closed while a vacuum is suitably supplied to hopper 12 which vacuum causes plate 102 to be moved or sucked upwardly iDto firm engagement with a resilient member 103.
10As shown in Fig. 5, the hopper 12 has a lowermost down-wardly extending circular flange portion 107 which defines the hopper opening 15. The outer cylindrical surface of flange portion 107 is encompassed by the resilient member 103 which member 103 extends downwardly beyond the lowermost edge of flange 15portion 107. The lowermost edge of member 103 is provided with a downwardly convergent taper to provide a thin lowermost edge portion 109 which is readily deflected by plate 102 to provide an essentially air tight seal between the side of plate 102 and edge portion 109. Member 103 is a resilient band formed from a suitable resilient material such as rubber or the like and is of a size to be expanded and, upon release, encompass the outer surface of flange portion 107 and be retained thereon.
Since member 103 engages the upwardly moving cover 102, member 103 is preferably retained on flange portion 107 by a suitable encompassing clamp 111 which is adjustable to vary the clamping force on member 103. Plate 102 is formed from a suitable rigid material which is of light weight such as aluminum or the like and is provided with a downwardly and outwardly flared flange portion to provide a firm engagement with the lower edge 109 when a vacuum is applied to hopper 12.

~L257301 ~, As is known, loader 10 has a lower outwardly extending mounting plate 16 which is provided with an opening 110, out-wardly adlacent chamber 14, through which a switch 108 extends.
Switch 108 is provided with suitable known contacts (not shown) s which are moved into and out of electrical engagement with each other upon movement of shaft 10~ in opposite arc~late directions. Suitable electrical leads or wires encased in a suitable sheath 114 extend from switch 108 and are suitably connected to a control, such as device 64, for controlling the electrical energi~ation of motor 60 in a well known manner.
Inasmuch as the structure and circuitry for applying a vacuum to hopper 12 in such manner is well known, further description or illustration thereof is not necessary for the understanding of this invention to one skilled in the relevant art. Switch 108 is not the sole control of the energization of motor 60 as motor 60 is controlled in various well known manners.
Switch 108 is supported within opening 110 by means of an adapter plate 116 which plate 116 is suitably rigidly secured to mounting plate 16 such as by a metal screw 118. Switch 108 is secured to plate 116 by machine screws 120 extending through plate 116 and into suitable threaded openings 122 in switch 108.
Switch 108 is a purchased component and adapter plate 116 is a formed member rigidly secured to both plate 16 and switch 108 in any suitable manner so that the upper portion of switch 108 is located above plate 16 whereby the switch 108 is exposed to ambient air. ~he lower portion of switch 108 with shaft 106 must be located below plate 16 in order to permit proper movement of valve plate 102. Accordingly, the particular form of plate 116 is of little consequence so long as switch 108 is properly rigidly supported and preferably supported for cooling by ambient air.

25730~

~_ Arm 104 of assembly 100 i9 of any suitable configuration to provide the motion of valve plate 102 as described herein.
As shown, with plate 102 extending horizontally, arm 104 consists of an initial portion 124 extending downwardly and outwardly S from the undersurface of plate 103 and an outer portion 126 extending upwardly and outwardly with respect to portion 124.
Portions 124 and 126 are in the form of a link which permits valve plate 102 to move arcuately between its closed position to its open position (somewhat less than 90 degrees from its closed position - see Figs. 3 and 4). With plate 102 in the open position, material from hopper 12 flows gravitationally downwardly through opening 15. Portion 124 is suitably rigidly secured to the undersurface of plate 102 such as by being brazed or welded thereto.
Portion 126 is suitably rigidly connected to shaft 106 in any suitable manner such that the arcuate movement of valve plate 102 in opposite arcuate directions permits a corresponding arcuate movement of shaft 106 about the elongated central rota-tional axis of shaft 106. Thus when plate 102 moves clockwise with reference to the showing of Fig. 2 to its open position as shown in dotted outline in Figs. 3 and 4, shaft 106 moves one or more selected contacts of switch 108 clockwise into an off position whereby the motor 60 cannot be electrically ener-gized for so long as plate 102 remains in the open position.
When plate 102 moves counterclockwise, with reference to the showing of Fig. 2, such contact or contacts of switch 108 are moved into a closed position to permit motor 60 to be electri-cally energized. Accordingly, for this invention a suitable electrical switch is selected for switch 108 in which the move-ment of actuating shaft 106 through an arc is matched to the ~ .
.

._ ~

~25730~

~- arcuate movement of plate 102. That is, the arcuate movement of plate 102 is equal to the arcuate movement of switch 108 between the on and off positions thereof. Since fine material is being conveyed, switch 108 is a sealed unit as is known in the electrical switch art. Further, since switch 108 has its upper end extending above plate 16 the switch 108 is cooled by the ambient air around the loader 10. Such cooling is desirable when heated material is conveyed as is common in the plastic molding industry.
As shown, the outer end of portion 126 of arm 104 is provided with a laterally extending through bore 113 through which shaft 106 extends. A set screw 105 is threadedly carried by arm portion 126 and engages shaft 106 so that shaft 106 and arm 104 move together. Spaced weights 130 are pivotably carried by shaft 106 on opposite sides of outer portion 126 to permit the force necessary to open plate 102 to be varied, as desired.
Weights 130 are provided with suitable bores such as through bore 132 in the weight 130 closest to switch 108 and a blind bore (not shown) in the other weight 130 for free pivotal support with relation to shaft 106. Weights 130 extend outwardly of the longitudinal central axis of shaft 106 and are suitably releasably and rigidly secured to each other by suitable means.
As shown, an axial through bore and axial threaded bore in the respective weights 130 lying on an axis parallel to the longi-tudinal central axis of shaft 106 receive a threaded and headed fastener 134 extending freely through the axial through bore in one of the weights 130 and into threaded engagement with the threaded bore in the other weight 130 to selectively clamp the weights 130 axially together in a known manner. Weights 130 may have any suitable facing surfaces to permit their being _g_ . ~

-- ~L25730~

releasably clamped together. Weights 130 are also of a thickness that, when clamped together, the opposite facing portions out-wardly adjacent shaft 106 firmly clamp the arm portion 126 therebetween. If desired, a resilient washer 115 may be located between weights 130 and with fastener 134 extending therethrough to insure a firm clamping action on arm portion 126. Also, as shown, weights 130 may have the portion thereof outwardly of arm portion 126 of a greater thickness than the portions thereof which clamp arm portion 126 whereby the outer end of arm portion is enclosed to a large extent by the weights 130.
Assuming that material is to be supplied to hopper 12 and that the plate 102 is in the closed position as shown in Fig. 3 and the motor 60 is energized, motor 60 drives pump 58 to apply a vacuum to hopper 12 to draw material 27 into hopper 12 through supply line 24. The time period for energizing motor 60 is controlled by timer 64 in a known manner until hopper 12 has received the desired amount of material as determined by the time period of timer 64. When such time period is completed the motor 60, and consequently pump 58, is deener-gized and atmospheric pressure will exist above the material in the hopper 12. The time period is set that that amount of material delivered to hopper 12 is of sufficient weight ~the vacuum being discontinued) to exert a force on the upwardly facing area of plate 102 to cause plate 102 to move in a clock-wise direction to an open position as previously described.
As is known, the material is discharged from hopper 12 into a lower hopper and, if an excess of material is available for discharge into the lower hopper, the discharged material will hold the plate 102 open so that the contacts of switch 108 _ . _ . . . .. . . . . ~ . . _ _ . _ .

~L25730~

remain open and no additional material is delivered to hopper 12.
As material is delivered from the lower hopper for the molding process the level of material in the lower hopper decreases until such time as the material does not interfere with the return of plate 102 to its closed position. It is to be realized that in the supplying of a single loader 10 the timer 64 is set so that normally full loads of material are discharged from hopper 12 and that after being discharged such full loads do not restrict the return counterclockwise movement of plate 102.
Upon movement of plate 102 in a counterclockwise direction plate 102 moves into a lower juxtaposition with the lower edge 109. Upon counterclockwise movement of plate 102 the contacts of switch 108 are simultaneously moved into their on position so that, subject to the other controls such as timer 64, the loader 10 is ready to receive more material and does receive material when all the controls are appropriately energized. If desired, plate 102 may be provided with an upwardly extending spherical surface 117 rather than the flat surface of Fig. 2.
As stated, the weight of material above plate 102 causes plate 102 to move into an open position. As is known, the bulk density of material conveyed into a hopper 12 varies considerably. This invention provides weights 130 which can be adjusted with respect to the longitudinal rotational axis of shaft 106 so that the force required to effect opening of plate 102 can be varied. With the above described structure the location of the weights 130 with respect to the central rotation axis of shaft 106 will, in conjunction with the weight of plate 102 and a portion of arm 104, will determine the force . _ . _ . _ . _ . _ 2S730~

f' that the material in chambers 13 and 14 of hopper 12 must exert on plate 102 to cause plate 102 and arm 104 to move downwardly.
Specifically, with reference to Figs. 4 and 5, the weight of cover 102 and the portion of arm 104 to the right of the vertical plane passing through the central axis of shaft 106 ~as will any other weight associated with arm 104 to the right of such vertical plane such as the weld material) will tend to move cover 102 and arm 104 in a clockwise direction. The total weight to the left of such axis of shaft 106 including weights 130 will exert a counterclockwise effect upon plate 102 and arm 104. The counterclockwise effect exceeds the clockwise effect so that plate 102 remains closed until the weight of the material in hopper 12, plus the clockwise effect of the weight of plate 102 and arm 104, exerts a force on plate 102 to overcome the continuously exerted clockwise effect of weights 130 and the portion of the weight of arm 104 to the left of such vertical plane. ~3y selectively locating the weights 130 to the right or left side the total counterclockwise effect of weights 130 can be varied. Further, by selectively locating the weights 130 with respect to the right or left side of the central axis of shaft 106, the total counterclockwise effect of weights 130 can be varied as the portions of the mass of weights 130 move toward or away from a horizontal plane passing through the central axis of shaft 106. Since the counterclockwise force effect can be varied, the varying force exerted by the material on -~ plate 102 can be compensated for so that a selected clockwise force will be required to cause plate 102 to move to the open position. Obviously, the force effect of weights 130 will move the plate 102 from its open to its closed position provided plate 102 is free to so move.

~.2573~

In adjusting the relative position of weights 130 with relation to shaft 106, fastener 134 is backed out of the threaded bore so that the clamping force on portion 126 of arm 104 is released. With the clamping force released weights 130 are pivoted about shaft 106 to a desired position whereat fastener 134 is tightened to reclamp portion 126.
Although the invention has been described with relation to a loader including a motor and vacuum pump, the valve assembly is equally adapted for use with material receiving hoppers which are connected to a common vacuum source. Inasmuch as such common vacuum sources and the controls therefor are well known, it is not believed necessary to illustrate such systems and the controls therefor for a complete understanding of the conveying systems in which the structure of this invention can be advan-tageously used. Also, switch 108 preferably has electrical contacts which are moved quickly into or out of electrical contact to prevent undesired electrical arcing. Many types of switches for such operation are well known in the electrical switch art and are commercially available.
Figs. 6 to 9 illustrate a presently preferred embodiment of this invention in which like reference numerals have been used to identify structures identical to those previously described with respect to Figs. 1 to 5. As shown, a cover or valve plate 202 closes against the lower tapered edge 109 of the resilient member lOi which member 103 is located and sup-ported in the same manner as previously described. Plate 202 has an upwardly extending upper spherical surface 117 with the lowermost portion of the spherical surface 117 engaging edge 103 in the manner as previously described-with respect to plat- 102. Plate 202 is supported on a formed arm 204 consisting ~57301 of an elongated formed portion 206 of a relatively thin section rigidly connected to a relatively thick formed portion 208.
Portions 206, 208 and plate 202 are of any suitable rigid material such as aluminum, whereby portions 206 and 208 can be S suitably welded or brazed together at their junction and portion 206 can be suitably welded or brazed to the undersurface of plate 202. A weld 207 is shown connecting portions 206 and 208.
With such structure the upper surface 201 of arm 204 is in complementary engagement with the undersurface of the spherical section forming surface 117.
Portion 208 is split horizontally (Fig. 6) from its outer edge to closely adjacent its juncture edge with portion 206 by means of a groove 212 whereby portion 208 has upper and lower identical sections 210 and 211, respectively, which sections 210 and 211 are movable towards and away from each other. Essentially half bores extend laterally through sections 210 and 211 in lateral alignment to form a split, lateral through bore 214. Split bore 214 has its central axis on the central horizontal plane of groove 212 and coincident with the central axis of shaft 106. The innermost end of groove 214 is provided with a similar but smaller diameter lateral through bore 213 to facilitate the movement of the sections 210 and 211 towards and away from each other. Sections 210 and 211 have transversely aligned through bores intermediate bores 213 and 214 for receiving a threaded and headed fastener 219. The body of fastener 219 passes freely through one of such bores and the free end thereof threadedly engages the threaded interior of the other of such bores in a well known manner. h7ith such structure shaft 106 is freely inserted through bore 214 and fastener 220 tightened until shaft 106 is firmly retained within bore 214 by the ~25730~
,.

flexure of sections 210 and 211 towards each other whereby arm o~
204 and shaft 106 rotate together. The outermost segments of sections 210 and 211 are essentially, in plan, in the shape of the quadrant of a circle with each quadrant having a center coincident with the center of bore 214. Each quadrant segment of sections 210 and 211 has, in plan, an arcuate groove 220 adjacent its outer edge with each of the grooves 220 having a common central arc with a center coincident with the center of split bore 114. The adjacent ends of grooves 220 are located adjacent groove 212 and the outer ends of grooves 220 are adjacent the outer surfaces of the quadrant segments of sections 210 and 211, respectively. The inner edge of the quadrant segments are located in a common plane which passes throuah bore 214 adjacent the center thereof.
The quadrant segments of portion 208 are closely received between a pair of overlying weights 230. Weights 230 are, in plan, essentially semicircular in form with a half circular stepped groove extending inwardly from the diametrically extending side 221 thereof. Each half of such stepped groove is shown in the weights 230 of Fig. 8. Such stepped groove has a relatively ; small radiused portion 224 which is of a radius to freely receive the shaft 106 therein in longitudinal relationship. Each stepped groove has a relatively large radiused portion 226 which is of a radius to slideably receive the outer periphery of the quadrant segments of portions 210 and 211 therein. With such structure a planar arcuate surface 228 on each weight 230 is formed between the portions 224 and 226. One weight 230 is provided with four arcuately spaced through bores 232 through which the body portions of elongated threaded and headed fasteners 236-freely extend.

: ~ .

~ 15-~25730~

~, The other weight 230 is provided with four arcuately spaced threaded through bores 234 which threadedly engage the threaded portions of fasteners 236. When overlying each other bores 232 and 234 have aligned central axes which are on overlying axes having a center coincident with the center of bora 214.
With the above described structure the weights 230 are placed in overlying relationship with surfaces 228 facing each other whereby the described stepped cavity is formed therebetween.
The quadrant segments of portion 208 of arm 204 are located in the portion of the cavity formed by the opposed portions 228 with the outer periphery thereof being slideably engageable with the inner arcuate surface of that portion of the cavity. At the same time the quadrant segments of portions 210, 211 slideably engage the opposed surfaces 228. When the quadrant segments are so located in such cavity, grooves 220 are between the bores 232 and 234 and the grooves 220, bores 232 and 234 being on overlying arcs of the same radius with respect to the center of bore 214. Each opposed pair of bores 232 and 234 can receive a fastener 236 which passes freely through a bore 232, a portion of a groove 220, and into threaded engagement with the bore 234 aligned therewith.
One way of assembling the structure of Figs. 6 to 8, is to first clamp arm 204 to shaft 106 as described. Then weights 230 are placed on opposite sides of the quadrant segments of portion 208 with bores 232 and 234 aligned with grooves 222.
Fasteners 236 are then inserted through the bores 232, 234 aligned with the upper end of each ~roove 220, respectively, and into threaded engagement with cooperable bores 234 (see Fig. 6).
Tightening of fasteners 236 to weights 230 rigidly secures the weights 230 to the quadrant portions of portion 208 of arm 204 and thereafter such entire assembly will rotate as a unit with _ _ ., . . _ . . . _ .. . _ . _ _ ., ..... _ ~25730~

shaft 106 about the central axis of shaft 106. The location of the weights 230 with reference to the central axis of shaft 106 will determine the force needed to open valve plate 202 in the manner as previously described.
One easy method of varying the counterbalancing effect of weights 230 when fasteners 236 extend only through the upper ends of grooves 220 (as shown in Fig. 6) respectively, is to loosen the fasteners 236 and rotate the weights 230 in a clockwise direction as desired and then reclamp the quadrant segments of portion 208 by tightening the loosened fasteners 236. As the weights 230 are pivoted with respect to the axis of the shaft 106 the effective weight of the weiahts 230 can be varied and the closing force on the plate 202 can be varied as previously described. Depending on the particular force desired to cause opening of plate 202, fasteners 236 can pass through the lower ends of each groove 220 in which event the weights 230 are rotatable (when released) in a counterclockwise direction.
Inasmuch as the various components described rotate relative to each other, such components are designed so that their central axes are coincident with the longitudinal rotative axis of shaft 106 and split bore 214. Also, since the central axis of shaft 106 is the axis about which the weights 230 are positioned, the effect of the weight of the structure to one vertical side Iwith respect to Fig. 6) of the central axis of shaft 106 is counteracted by the effect of the weight of the structure on the other vertical side of such axis. The effect of the weight on the left side of such axis determines the closure force on plate 202 and such closure force must be overcome by the material in the hopper 12 to move plate 202 to its open position.

~257;~0~
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~_ Since the quadrant segments of portion 108 are clamped, ¦ the weights 230 are preferably made from steel to provide a ¦ higher density material than aluminum and to enable a high clamping force to be applied. The terms inner, outer, horizontal and vertical are employed for ease in describing the above embodiment; however, such relative designations may not always exist. All that is essential for this invention is that the weights 130 and 230 be gravitationally effective. In order to permit the entire assembly to be removed without damaging the described discharge valves, a tubular flange 255 extends downwardly from flange 16 and surrounds the discharge assembly.
Having described preferred embodiments of this invention in accordance with the Patent Statutes and having set forth various modifications thereto, those skilled in the art will be cognizant of the fact that still other modifications can be made without departing from the spirit and scope of this inven-tion. Accordingly, the following claims are to be construed as including modifications of the structures defined herein as ¦ ~o=~d b- t=o-n to those skillel i= the relev:=t art.

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i I

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a vacuum loader for receiving granular, pulverant, fine or the like air entrainable material the improvement com-prising: a material receiving hopper having an upstanding material receiving chamber portion with a lowermost material discharge opening, a control means supported with relation to said hopper with an elongated actuating shaft member extending therefrom, said shaft member being movable between spaced first and second control positions of said control means with one of said positions being adapted to be operatively connected to means for transporting such a material to such a material receiving chamber portion, a movable valve having a closure portion and an integral elongated arm member which arm member extends transversely of said shaft member and is connected to said shaft member whereby said valve and said shaft member have conjoint movement, said closure portion being supported with relation to such hopper to close said opening with said shaft member being located in said one of said positions and said closure portion being movable out of engagement with said opening to permit material to be gravitationally discharged from said chamber portion through said opening and to move said shaft member into the other of said positions, and means carried by at least one of said members for constantly urging said closure portion towards said opening.

2. In a vacuum loader as set forth in claim 1 wherein said last mentioned means is a counterweight carried by said shaft member.

3. In a vacuum loader as set forth in claim 2 wherein the relative position of said counterweight with respect to said shaft member is selectively variable.

4. In a vacuum loader as set forth in claim 2 wherein said counterweight consists of a plurality of members each of which is secured to said shaft member.

5. In a vacuum loader as set forth in claim 1 wherein said last mentioned means is a counterweight carried by said arm member.

6. In a vacuum loader as set forth in claim 1 wherein at least a portion of said control means is exposed to ambient air.

7. In a vacuum loader as set forth in claim 1 wherein said closure portion has an upwardly extending spherical configuration.

8. In a vacuum loader as set forth in claim 1 wherein said hopper has an outwardly extending mounting flange portion and means for securing said control means to said flange portion.

9. A vacuum loader as set forth in claim 8 wherein said flange portion has an opening through which said control means extends.

10. In a vacuum loader as set forth in claim 1 wherein said shaft member has an elongated axis of rotation and oscillates about said axis between said first and second control positions.