US3198272A

US3198272A - Packaging machine scales

Info

Publication number: US3198272A
Application number: US233731A
Authority: US
Inventors: Kenneth M Allen; Chester H Harper
Original assignee: HARPER Inc ALLEN
Current assignee: ALLEN-HARPER Inc; HARPER Inc ALLEN
Priority date: 1962-10-29
Filing date: 1962-10-29
Publication date: 1965-08-03
Anticipated expiration: 1982-08-03

Description

Aug. 3, 1965 K. M. ALLEN ETAL 3,198,272 PACKAGING MACHINE SCALES Filed 001:. 29, 1962 3 Sheets-Sheet 1 IN VEN TOR S.

KENNETH M. ALLEN BY CHESTER H. HARPER BUCKHORN, BLORE, KLAROUIST 8 SPARKMAN ATTORNEYS Aug. 3, 1965 K. M. ALLEN ETAL 3,198,272

PACKAGING MACHINE S CALES Filed Oct. 29, 1962 3 Sheets-Sheet 2 FIGS IN VEN TORS.

KENNETH M. ALLEN BY CHESTER H. HARPER BUCKHORN, BLORE, KLAROUIST 8 SPARKMAN ATTORNEYS Aug. 3, 1965 K. M. ALLEN ETAL PACKAGING momma SCALES 3 Sheets-Sheet 5 Filed Oct. 29, 1962 u m R u mmw m w: Q mm mm v9 g m l N2 02 v: 5 v2, mHm m l \05 TW. 9.. h MS WA NE W 40m A m Y R B m m H 0a m a E E @216 v9 E t LIT a Om N @E o. X

United States Patent charges material.

Another object of the invention is to provide a packaging machine scales which controls supply conveyor means to slow feed of material to the scales as material accumulated on the scales approaches a desired weight and then when that weight is reached to stop the conveyor.

Another object of the invention is to provide a packaging machine scales which discharges a hopper thereof.

A further object of the invention is to provide a hopper type scales which actuates a vibrator to vibrate a container receiving material from the scales.

Still another object of the invention is to provide a simple, effective and rugged device for accumulating, Weighing and discharging material.

A further object of the invention is to provide a cantilever scales.

A packaging machine scales illustrating certain featurcs of the invention may include hopper means for accumulating a supply of material from a conveyor together with scales means supportin the hopper means and actuating means operable by the scales means as the material in the hopper means approaches the desired Weight for slowing feed of material to the hopper means. The scales means may stop the feed of material to the hopper means altogether when the desired weight thereof has been accumulated in the hopper means, and then may actuate the hopper means to discharge the material therefrom into a container and to actuate a vibrator for the container to shake the container as the material is discharged therein to pack the material into the container.

A complete understanding of the invention may be obtained from the following detailed description of the packaging machine scales forming a specific embodiment thereof, when read in conjunction with the appended drawings, in which:

FIG. 1 is a fragmentary perspective view of a packaging machine scales forming one embodiment of the invention;

FIG. 2 is an enlarged, fragmentary elevation view of a conveyor control of the scales of 1;

FIG. 3 is an enlarged vertical section taken along line 3-3 of FIG. 2 and showing the control in one position;

FIG. 4 is an enlarged horizontal section of the control of FIG. 3;

FIG. 5 is a fragmentary, partially sectional view of a hopper portion of the scales of FIG. 1 and illustrating a discharge portion of the scales and a supply conveyor for the scales;

FIG. 6 is a vertical section taken along line 6-6 of FIG. 5; 7

FIG. 7 is a schematic view of the scales of FIG. 1 together with a hydraulic and electrical control system forming a portion thereof; and

FIGS. 8, 8a and 8b are sectional views showing portion of the scales of FIG. 1 respectively in a position in which a dribble weight is not yet picked up by a counterbalance of the scale, a position in which the dribble weight is just picked up by the counter-balance of the scales, and a position in which the dribble weight is raised by the counter-balance of the scales.

Referring now in detail to the drawings, there is shown therein a packaging scale including a hopper 10 receiving material from a conveyor ll which may be a conveyor of the type disclosed and claimed in copending application Serial No. 233,702 filed simultaneously herewith for Fluid Pressure Controlled Vibrating Conveyor. The hopper lift is adapted to discharge the material after a predetermined desired weight is accumulated therein through a discharge chute or funnel 12 into a packaging container 14 and to cause a vibrating mechanism 16 to be actuated to vibrate the container M as the material is discharged therein. The container 14 is conveyed by a conveyor 18 to its receiving position as shown in FIG. 7. The conveyor 13 and the vibrator 16 are disclosed and claimed in copending application Serial bio/233,730 filed on an even date herewith for Reciprocating Conveyor.

The scales include a pair of horizontal parallel cantilever beams 2t) and 22 (FIG. 1), which may be aluminum channel members having

end webs

24, 26, 28 and 39, respectively. The

web portions

24 and 28 are secured to fixed frame members 32 and 34 of a frame fixed to a supporting iioor or the like. The frame also includes

fixed angle irons

36 and 38, which are fixed relative to the floor. The end portions of the webs 26 and are fixed rigidly to the hopper it? at vertically spaced points thereon, the end 26 being fixed by a bracket 31 and rivets 33. The portion of the hopper 10 extending between the

webs

26 and 3% is rigid so that the

beams

20 and 22. form a parallelogram linkage with the hopper lit? and the fixed frame members 32 and 34. The

beams

24 and 22 supporting the hopper are rigid except for the

webs

2a, 26, 28 and 3h, which are flexible to permit the hopper ll) to move downwardly in proportion to the weight of the material accumulated in the hopper ll A counter-balancemechanism 40 includes a shaft 42 having V-shaped, downwardly opening recesses 44 near the ends thereof into which project knife-edge supports 46 supported by the

fixed frame members

36 and 38. A capstan segment 59 concentric with the shaft 42 is fixed to the shaft 42 and keyed thereto by suitable known means such as set screws (not shown). A counter-balance rod 52 has a forked end portion 54 rigidly fastened to one edge portion of the capstan segment so that the rod 552 is rigidly secured to the shaft 42 and moves therewith. A Vernier weight 56 is threaded on a rod 53 for adjustrnent therealong, the rod 58 extending substantially horizontally from one side of the shaft 42 and being keyed thereto.

A main counter-balance weight 60 is fixed in any desired adjusted position along the rod 52 by a set screw 62. The weight at normally urges the rod 52 in a counter-clockwise direction, as viewed in FIG. 1, to a position in which a permanent magnet 64 is spaced closely to an eccentric member 65. The magnet 64 is fixed to rod 52 by strap 65 and set screw 67. The member 66 is keyed to a shaft 63 rotatable manually by a knob and indicator 7d, the shaft 68 being mounted on an axis of rotation fixed relative to the frame members 32 and 34. The eccentric member as is composed of magnetic material. In this position of the rod 52, the rod engages a fixed stop 72 to space the magnet 64 from the eccentric adjustable member 66. The magnet 64 is thus spaced a predetermined distance from the eccentric member 66, which distance can be adjusted by turning the member 66 by the knob 70. The stop 72 is carried at a fixed height by a supporting bar '74 carried by the main frame of the scales.

amass 2 The magnet 64 holds the rod in engagement with the stop 72 until sufficient material accumulates in the hopper 111 to overcome both the force of the weight on the rod 52 and force between the magnet 64 and the member 66, and then permits the rod to swing away from the member 66 and stop 72 once these forces are slightly exceeded. As the rod moves away from the magnet '72, the force exerted by the magnet 64 is broken, and a dashpot mechanism 76 secured at its lower end to the beam 22 and having a piston rod 78 connected pivotally to the rod 52 slows swinging movement of the rod 52 in a clockwise direction as viewed in FIGS. 1 and 7. A magnet 80 (FIGS. 2-4) having

poles

82 and 83 carried by the rod 52 is adapted to first attract an armature 86 of a switch 84 as the rod 52 swings in a clockwise direction to bring the magnet 80 into proximity to the armature 86, and then after moving on upwardly releases the armature 86 which is spring returned to the position thereof shown in FIG. 4. When the magnet is brought up to the level of and into proximity with an armature 88, it moves the armature to close a switch 911. The switches 84; and 90 are mounted in fixed positions on a panel 92 of the main frame, and the rod 52 is movable in a slot 94 in the panel. The extreme upward movement of the arm or rod 52 is determined by the upper end of the slot 9 1 in which position the magnet 81 holds the switch 911 closed.

When the material in the hopper 11) reaches a predetermined weight approaching that which is desired for a given weight of material to be deposited into the can or container 14, the weight of the material presses the beam 22 downwardly with sufiicient force that a flexible cable 98 (FIGS. 1 and 7) secured at its lower end to the beam 22 and at its other end to the portion of the capstan 50 adjacent to the rod 52 turns the capstan to move the magnet 64 from the proximity of the cam 66. The rod 52 swings thus in a clockwise direction until it picks up a dribble weight device 1110. That is, the rod 52 moves from the position thereof shown in F163. 1, 7 and 8 up to the position thereof shown in FIG. 8a, in which position the rod 52 engages and has its further movement resisted by a pivotal lever 102 having a dribble weight 104 adjustably secured to the outer end portion of the rod 102. The lever 192 is pivotally mounted in a bracket 103 having a notch 105 and a bearing portion 107. A bearing 109 also supports the lever 1112 pivotally. The bracket 103 and bearing 109 are mounted on member 38 of the fixed frame of the scales. The notch 1115 limits downward movement of the free arm of the lever 102. At this time, the magnet 80 is adjacent the armature 86 and further movement is prevented by the dribble weight 104. Before closing of the switch 84 occurs, valve solenoid 108 of valve 110 is in a de-energized state and air under a predetermined low pressure is supplied, through a valve 112, check valve 115, and a known type of pressure regulating

valve members

113 and 114, from a source 116 of air under a predetermined high pressure to the lower end of a cylinder 118 of the conveyor 11. This holds the conveyor trough in a predetermined average position against a tension spring 120 fastened between the conveyor trough 11 and a supporting frame member 124. The spring 120 biases the trough 11 toward such position against the action of piston 126. The conveyor trough 11 is vibrated by means disclosed in the abovementioned application Serial No. 233,702, and feeds the material normally at a fast rate of feed.

When the switch 84 is closed, the solenoid 108 is energized to actuate the valve 110 to supply air under a higher pressure from known type of pressure regulating valve mechanism 127, to the cylinder 118, this pressure being designated a dribble pressure. At this time check valve 115 is closed because of the pressure of the air supplied from the valve mechanism 127 being greater than that of the air supplied by the pressure regulating mechanism 113. This higher dribble pressure of the air supplied to the cylinder 118 moves the piston 126 upwardly against the action of the spring 1211 to move the links 122 supporting trough 11 to more nearly vertical positions, in which positions the rate of feed of the material from the conveyor 11 is slowed to a dribble which is continued until the desired weight of material is accumulated in the hopper 111. Then the rod 52 lifts the dribble weight 104 and moves the magnet 80 out of operative relationship with the switch 34-, which reopens, and into operative relationship with the switch 91), the rod 52 having moved the dribble mechanism 100 to the position shown in FIG. 812.

When the switch 96 is closed its actuates solenoids 1 18, 1511 and 152. Actuation of the solenoid 148 actuates valve mechanism 154 to supply air under pressure to a pneumatic device 156 to swing a door 158 of the hopper 10 open. The door is suspended by hinge 161). When the hopper door 158 is opened, the material in the hopper 10 slides down an inclined bottom portion 162 thereof to the funnel 12 and into the container 14. Energization of the solenoid 1511 actuates a known valve mechanism 164 to connect the supply of air from the pressure regulating mechanism 114 tothe valve mechanism 112, and energization of the solenoid 152 actuates the valve 112 to cut off the pressure regulating mechanism 113 from the check valve 115 and connects the outlet of the valve 164 to the check valve 115'. Thus, the air under the highest pressure, which is that at which the air leaves the mechanism 114, is now supplied to the lower end of the cylinder 118. This increased pressure of the air moves the piston 126 to move the conveyor trough 11 up to a position in which the links 122 are more nearly vertical and in which no feed whatsoever of the material is made by the conveyor trough 11. This is the stop or cut-off position of the conveyor trough 11. Also, this actuation of the valve mechanism 164 removes air under pressure from the left-hand end of pneumatic switch actuator to break contacts 172 and make contacts 174. Making of' contacts 174 energizes solenoid 176 to cause air to be supplied under pressure to actuate the shaker or vibrator mechanism 16 to shake the container 11 as the material is discharged thereinto from the hopper 111. Breaking of the contacts 172 de-energizes solenoid 1811 to actuate valve 182 to cut oif a pneumatic conveyor driver 184 to permit the conveyor driver 184 to make a return or retracting stroke preparatory to feeding another empty container 14 to the packing or loading position under the chute 12. The operation of the driver 184 is disclosed in more detail in the above-mentioned copending application Serial No. 233,730, the return stroke being effected by a counter-weight 186.

After all the material in the hopper 10 is discharged therefrom, the lightened weight thereof permits the

beams

26 and 22, with the effect of the counter-balancing mechanism 4-1 to raise the hopper 10 and the rod 52 to pivot back to its normal position, which it does. At this time both the

switches

88 and 16 are open so that the solenoids 16%, 148 and 152 are de-energized to return the corresponding valves to their normal positions. This causes the pneumatic actuator 1711 to break contacts 174 and make contacts 172, which de-energizes the solenoid 176 to move the vibrator mechanism 16 to a retracted, non-operative position. Making of contacts 172 energizes the solenoid 1811 to cause the conveyor driver 184 to be actuated to move containers 14 to the right, the right-hand, filled container 14 being moved to an unloading position and the left-hand container 14, as viewed in FIG. 7, being moved to loading or filling position under the chute 12. The de-energization of the solenoid 1511 also causes the high pressure air to be cut off by the valve 164-, the de-energization of the solenoid 152 causing the air under the lower (or normal rate of feed) pressure to be supplied to the cylinder 118. The spring 1211 then pulls the conveyor trough 11 back to a position in which the links 122 are more inclined, which is the normal feed position of the conveyor trough, and material is supplied to the hopper 10. Just before this occurs, however, the de-energization of the solenoid 143 actuates the valve mechanism 154 to retract the piston rod 157 and the door 158 swings to its closed position through gravity. The cycle described above then is repeated. The door 158 normally is held in its closed position by magnets 19% (FIG. I) mounted on the sides of the hopper lit? in positions adapted to engage overhanging portions 192 of the door 158, which is of magnetic material.

The main frame also includes a fixed vertical member 1% (FIG. 5) which has rods 2% supporting the chute or funnel 12 in a position just slightly overlapping the hopper 1t) and bracketing the door of hopper Ill. The funnel 12 is in a position to catch all of the material discharged from the hopper l6 and deliver it to the container 14 positioned therebelow.

The scales described provides a very rugged, accurate and fast acting and easily adjustable weighing mechanism in combination with the conveyor 11. The main and dribble feed rates of such conveyor can be independently adjusted by merely adjusting the

pressure regulator valves

113 and 127 respectively. The final or total weight and dribble feed initiating weight can be roughly adjusted by moving the

weights

60 and 104 along their respective support rods. The total weight before stopping the feed of the conveyor 11 and emptying the hopper it) can be finely adjusted by rotating the vernier weight 56 on the threaded rod and the dribble feed initiating weight can be independently adjusted by turning the knob 74] to rotate the eccentric member 66 to thus adjust the weight on the scales required to move the scales rod or beam 52 from its initial position to the dribble feed position. It is to be noted that moving the rod 52 to such dribble feed position moves the magnet 64 sufficiently far from the eccentric member 65 of magnetic material that there is substantially no attractive force between the magnet 64 and member 66. This means that adjustment of the member 66 has a material effect upon the weight on the scales at which the dribble feed is initiated but has substantially no effect on the total weight on the scales which results in stopping of the dribble feed.

It is to be understood that the above-described arrangements are simply illustrative of the application of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is:

1. In a packaging machine scales,

platform means for receiving material to be weighed,

feed means for feeding material to the platform means,

yieldable means supporting the platform means,

a lever,

means mounting the lever pivotally,

means connecting the platform means to the lever means, first magnetic means carried by the lever, second magnetic means mounted in a fixed position such that when there is less than a predetermined Weight on the platform means the first magnetic means is close to and is strongly attracted to the second magnetic means and operable as soon as said predetermined weight is on the platform means to permit thelever to be swung with asnap action to a position in which the first magnetic means is remote from the second magnetic means,

counterbalancing weighing means engaged by the lever after the lever is swung to said position in which the first magnetic means is remote from the second magnetic means,

and means operable by the lever when the lever is so swung for slowing the feed means.

2. In a packaging machine scales,

platform means for receiving material to be weighed,

feed means for feeding material to the platform means,

yieldable means supporting the platform means,

a lever,

means mounting the lever pivotally,

means connecting the platform means and the lever,

first magnetic means carried by the lever,

second magnetic means mounted in a fixed position such that when there is less than a predetermined weight on the platform means the first magnetic means is close to and is strongly attracted to the second magnetic means and after said predetermined weight is on the platform means the lever is swung to a position in which the first magnetic means is remote from the second magnetic means,

third magnetic means mounted on the lever,

first magnetically actuated switch means positioned so as to be actuated by the third magnetic means during the initial portion of the swinging movement of the lever for actuating the feed means to slow the feed means,

and second magnetic switch means positioned so as to be actuated by the third magnetic means during a portion of the swinging movement of the lever subsequent to actuation of the first magnetic switch means for stopping the feed means.

3. In a packaging machine scales,

a fixed member, a platform channel having a strap portion at a first end thereof, the free end of the strap portion being fixed rigidly to the fixed member,

material receiving means mounted on the second end of the platform channel remote from the first end thereof,

feed means operable normally at a fast rate of feed and adjustable to a slow rate of feed,

a pivot mounted in a fixed position near to the second end of the platform channel,

a lever mounted pivotally on the pivot near one end of the lever,

a first magnet fixed to the central portion of the lever,

a flexible strand member having one end secured to the capstan and the other end secured to the platform channel,

a weight on the lever,

a first magnet fixed to the central portion of the lever,

an adjustable magnetic member eccentrically mounted on a fixed pivot in a position in which the first magnet is close to and is strongly attracted to the magnetic member when there is less than a first predetermined weight on the material receiving means and when said predetermined weight is on the material receiving means the lever swings the first magnet away from the magnetic member,

dashpot means connected to the lever for slowing swinging movement thereof,

a second magnet on the end of the lever remote from the capstan,

first magnetic means so positioned as to be operated by the second magnet during the initial portion of the swinging movement of the lever to actuate the feed means to operate at said slow rate of feed.

and second magnetic means so positioned as to be operated by the second magnet a predetermined period of time after the first magnetic means is actuated and serving to stop the feed means.

4. In a packaging machine scales,

a fixed member,

a platform channel having a strap portion at a first end thereof, the free end of the strap portion being fixed rigidly to the fixed member,

a knife edge pivot mounted in a fixed position near to the second end of the platform channel,

a lever mounted pivotally on the pivot near one end of the lever,

a capstan fixed to the lever and centered on the knife edge pivot,

a flexible stand member having one end secured to the capstan and the other end secured to the platform channel,

a weight on the lever,

a magnet fixed to the central portion of the lever,

an adjustable magnetic member eccentrically mounted on a fixed pivot in a position in which the magnet is close to and is strongly attracted to the magnetic member when there is less than a first predetermined Weight on the material receiving means and when said predetermined weight is an the material receiving means the lever swings the magnet away from the magnetic member,

and means operable by swinging movement of the lever to actuate the feed means to operate at said slow rate of feed.

5. In a packaging scales,

a scales platform movable downwardly as material being weighed accumulates thereon.

feed means normally operable to feed material to the platform at a predetermined rate and actuable to feed material to the platform at a substantially lower rate of feed than said predetermined rate,

the feed means also being actuable to stop feed of the material,

a lever,

bearing means fulcruming the lever,

means connecting the lever to the platform for pivoting the lever by downward movement of the platform,

means restraining pivotal movement of the lever and releasing the lever for movement when a predetermined weight of material accumulates on the platform,

means operable by the lever during the initial portion of movement of the lever for actuating the feed means to said substantially lower rate of feed,

counterweight means in the path of movement of the lever and engaged by the lever after the lever has been released by the restraining means for restraining further movement of the lever until a second predetermined weight of material accumulates on the platform and releasing the lever for further movement when said second predetermined weight has accumulated on the platform,

and means operable by the lever during said further movement for actuating the feed means to stop feed of the material.

6. In a packaging machine scales,

material-receiving means,

counterbalance means supporting the material-receiving means and movable by accumulation of material on the material-receiving means from a first position to a second position,

stop means to limit movement of the counterbalance means to the first position thereof in a direction away from the second position thereof,

first magnetic means on the counterbalance means and movable therewith,

second magnetic means,

and rotatably adjustable shaft means rotatable on a fixed axis and mounting the second magnetic means eccentrically thereon in a selected position in which the first magnetic means is close to the second magnetic means when the counterbalance means is in its first position and the first magnetic means is remote from the second magnetic means when the counterbalance means is in its second position.

".7. In a packaging machine scales,

a cam of magnetic material rotatable on a fixed axis,

means for moving the cam to a selected position of rotation,

a counterbalance lever means mounted pivotally on a fixed axis,

material-receiving means counterbalanced by the lever means and biasing the lever means away from a first position thereof toward a second position thereof,

stop means for limiting movement of the lever means beyond the first position thereof in a direction away from the second position thereof,

and a magnet carried by the lever means in a position in which the magnet is close to and exerts a strong attracting force on the cam when the lever means is in its first position and the magnet is spaced far from and exerts substantially no attracting force on the cam when the lever means is in the second position thereof.

8. In a packaging machine scales,

platform means for receiving material to be weighed,

yieldable means supporting the platform means,

a counterbalancing lever,

means mounting the lever pivotally,

means connecting the platform means to the lever so that the lever counterbalances the platform means,

first magnetic means carried by the lever,

second magnetic means mounted in a fixed position such that when there is less than a predetermined we'i ht on the platform means the first magnetic means is close to and is strongly attracted to the second magnetic means and after said predetermined weight is on the platform means the magnetic force of attraction is overcome and the lever is abruptly swung to a position in which the first magnetic means is remote from the second magnetic means,

and weighing means operable only after the lever is swung to the position thereof in which the first magnetic means is remote from the second magnetic means,

the weighing means including counterbalancing means serving to operatively engage the lever after the lever is swung toward said position in which the first magnetic means is remote from the second magnetic means.

9. in a packaging machine scales,

hopper means,

means mounting the hopper means movably,

fixed magnetic means,

second magnetic means normally held against movement by the fixed magnetic means and adapted to hold the hopper means against movement until a predetermined weight of material has been placed in the hopper means and then permit the second magnetic means to snap away from the fixed magnetic means,

the second magnetic means being movable by the hopper means to a position relative to the fixed magnetic means in which the pull between the magnetic means is insignificant,

and weighing means including means for supporting the hopper operable when the pull between the magnetic means is insignificant to weigh the contents of the hopper means.

References Cited by the Examiner UNITED STATES PATENTS 1,066,656 7/13 Richardson 177104 1,923,745 8/33 Platzer 177-53 2,613,053 10/52 Dorrington et al. 17779 2,746,708 5/56 Gilchrist 17779 2,995,783 8/61 Lytton 1969 3,107,743 10/63 nobel 177-116 LEYLAND M. MARTiN, Primary Examiner.

LEO SMILOW, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,198,272 August 3, 1965 Kenneth M. Allen et al corrected below.

Column 4, line l2, for "its" read it column 6, line 39, for "a first magnet fixed to the central portion of the lever," read a capstan centered on the pivot and fixed to the lever, line 60, for "feed." read feed, v column 7, line 7, for "stand" read strand line 17, for "an" read on same column 7, line 25, for "thereone" read thereon,

Signed and sealed this 15th day of February 1966:

ZAL)

est:

NEST W. SWIDER EDWARD J. BRENNER :sting Officer Commissioner of Patents

Claims

1. IN A PACKAGING MACHINE SCALES, PLATFORM MEANS FOR RECEIVING MATERIAL TO BE WEIGHED, FEED MEANS FOR FEEDING MATERIAL TO THE PLATFORM MEANS, YIELDABLE MEANS SUPPORTING THE PLATFORM MEANS, A LEVER, MEANS MOUNTING THE LEVEL PIVOTALLY, MEANS CONNECTING THE PLATFORM MEANS TO THE LEVER MEANS, FIRST MAGNETIC MEANS CARRIED BY THE LEVER, SECOND MAGNETIC MEANS MOUNTED IN A FIXED POSITION SUCH THAT WHEN THERE IS LESS THAN A PREDETERMINED WEIGHT ON THE PLATFORM MEANS THE FIRST MAGNETIC MEANS IS CLOSE TO AND IS STRONGLY ATTRACTED TO THE SECOND MAGNETIC MEANS AND OPERABLE AS SOON AS SAID PREDETERMINED WEIGHT IS ON THE PLATFORM MEANS TO PERMIT THE LEVEL TO BE SWUNG WITH A SNAP ACTION TO A POSITION IN WHICH THE FIRST MAGNETIC MEANS IS REMOTE FROM THE SECOND MAGNETIC MEANS, COUNTERBALANCING WEIGHING MEANS ENGAGED BY THE LEVER AFTER THE LEVER IS SWUNG TO SAID POSITION IN WHICH THE FIRST MAGNETIC MEANS IS REMOTE FROM THE SECOND MAGNETIC MEANS, AND MEANS OPERABLE BY THE LEVER WHEN THE LEVER IS SO SWUNG FOR SLOWING THE FEED MEANS.