Combinatorial weighing apparatus

A combinatorial weighing apparatus has a distribution table adapted to distribute a material to be weighed and supplied thereto, a plurality of distribution supply devices arranged radially around the distribution table and adapted to receive the material distributed by the distribution table, hoppers disposed below respective distribution supply devices and adapted to receive the material from the distribution supply devices, weight sensors annexed to said hoppers and adapted to weigh the material in respective hoppers, computing means adapted to compute the total weight of the material and to select the best combination of hoppers which provides a total weight most closely approximating a preset target weight, and a hopper drive means adapted to selectively drive the hoppers to make the hoppers constituting the selected best combination discharge the material therefrom. The hopper drive means is disposed so as to be surrounded by the hoppers. The apparatus has a single disc-shaped feeder base common to all distribution supply devices. The distribution supply devices are arranged on the common feeder base radially at a regular interval.

BACKGROUND OF THE INVENTION 
The present invention relates to a combinatorial weighing apparatus and, 
more particularly, to a combinatorial weighing apparatus of the type 
having a plurality of weighing hoppers and adapted for weighing materials 
through the steps of finding the weight of a batch of material in each 
weighing hopper, selecting the combination of weighing hoppers which gives 
a total weight equal to or closest to a preset target weight (referred to 
as the "best" combination, hereinunder) and discharging the batches of 
material from the weighing hoppers constituting the selected combination. 
Generally, a combined weighing apparatus incorporating a computer, referred 
to as "computer scale", is used for accurately weighing materials which 
exhibit large variation in weight from one to another, e.g. fruits and 
vegetables, confectionaries, fabricated articles, perishables or the like. 
In such a combinatorial weighing apparatus, batches of the material to be 
weighed are put into a plurality of weighing hoppers and weighed in 
respective hoppers. Then, the apparatus selects a combination of batches 
which provides a total weight closest to the target weight within a 
predetermined tolerance. The batches constituting the selected combination 
are then discharged and the evacuated weighing hoppers are charged with 
new batches of the material for the next cycle of the weighing operation. 
This operation is repeated to achieve the automatic weighing of the 
material. 
Referring to prior art FIG. 1 schematically showing the mechanism of a 
combinatorial weighing apparatus, a distribution table 1 is adapted to 
disperse the material to be weighed in the radial direction and to 
distribute the dispersed batches of material to a plurality of weighing 
stations 2 arranged radially around the distribution table 1. The 
distribution table 1 is adapted to be vibrated by a vibrator or the like, 
so that the dispersed material is distributed to the weighing stations 2 
as a result of the vibration of the table for a predetermined time length. 
In the illustrated embodiments, n weighing stations are arranged, and each 
weighing station 2 includes a distribution supply device 2a, pool hopper 
2b, pool hopper gate 2c, weighing hopper 2d, weight sensor 2e, weighing 
hopper gate 2f and a hopper drive unit 2g. As shown in FIG. 2, the 
distribution supply device 2a is composed of a feeder base 2a-1 having a 
predetermined shape and a trough 2a-2 mounted on the feeder base 2a-1 
through an electromagnet 2a-3 and a leaf spring 2a-4. As will be seen from 
FIGS. 3 and 4, a plurality of feeder bases 2a-1 are carried by a circular 
support member 3 through respective coiled springs 2a-5 and are arranged 
radially along the outer periphery of the distribution table 1. In 
operation, the material to be weighed is put on the distribution table 1 
while the latter is vibrated reciprocatingly and spirally by an 
electromagnetic vibrator 4, so that the material is dispersed radially 
outwardly along the conical top surface of the distribution table 1 into 
separate batches which in turn are delivered to respective troughs 2a-9. 
The batch of material supplied to each trough 2a-2 is conveyed through the 
latter in the direction of the arrow as a result of a linear reciprocating 
vibration of the trough 2a-2 by the electromagnet 2a-3, and is put into 
the pool hopper 2b (FIG. 1) from the end of the trough 2a-2. 
Referring back to FIG. 1, each pool hopper 2b is provided with a pool 
hopper gate 2c. As this pool hopper gate 2c is opened by the operation of 
the hopper drive unit 2g, the batch of material contained by the pool 
hopper 2b is put into the weighing hopper 2d. Each weighing hopper 2d is 
provided with a weight sensor 2e for weighing the batch of material put 
into the weighing hopper 2d. The output from the weight sensors 2e are 
delivered to a combination controlling section (not shown) which selects 
the best combination of the batches of material which provides a total 
weight most closely approximating the target weight within a predetermined 
tolerance. Each weighing hopper 2d is provided with a weighing hopper gate 
2f. After the selection of the best combination, only the weighing hopper 
gates 2f of the weighing hoppers constituting the best combination are 
opened to let the batches of material go out of these hoppers. These 
batches of material are then collected at the lower central portion of the 
weighing apparatus through a collecting chute 5. The collecting chute 5 
has a form resembling a conical funnel, and the batches of material 
dropping onto the peripheral portions of the chute are gathered at the 
central portion thereof naturally by the force of gravity or forcibly by a 
scraping means (not shown) or the like. 
At the initial stage of the weighing operation, the weighing hoppers 2d are 
charged with respective batches of material to be weighed. The weight 
sensors 2e annexed to these weighing hoppers 2d weigh the batches of 
material and deliver weight signals L.sub.1 to L.sub.10 to the combination 
control section which is not shown. The combination control section then 
makes a computation of total weight for various hopper combinations and 
selects a combination which provides a total weight most closely 
approximating the target weight within a predetermined tolerance. The 
hopper drive unit 2g then opens the weighing hopper gates of the weighing 
hoppers constituting the selected best combination. In consequence, the 
batches of material providing the best combination are discharged from 
these hoppers 2d into the collecting chute 5. Then, the pool hopper gates 
2c are opened to charge the evacuated weighing hoppers with new batches of 
material. At the same time, the distribution supply devices 2a 
corresponding to the evacuated pool hoppers 2b are vibrated for a 
predetermined time to charge the empty pool hoppers 2b with the material 
to be weighed. Then, the selection of the best combination is made in the 
same manner as that explained before. The weighing operation by the 
combinatorial weighing apparatus is thus performed repeatedly and 
continuously. 
In the combinatorial weighing apparatus of the type mentioned above, it is 
essential that the supply and discharge of the materials to and from 
sections such as pool hoppers 2b, weighing hoppers 2d or the like have to 
be made independently without being interfered with by other sections. In 
the conventional combinatorial weighing apparatus, therefore, a plurality 
of drive units 2g are installed independently outside respective sections 
such as pool hoppers, weighing hoppers or the like, to ensure smooth 
supply and discharge of the material to and from respective sections. 
According to this arrangement, however, the number of parts is increased 
impractically and the efficiency of use of power is lowered undesirably 
because a multiplicity of drive units 2g are arranged around respective 
sections such as pool hoppers 2b and weighing hoppers 2d. In addition, 
since the drive units 2g are arranged at the outer side of the pool 
hoppers 2b and the weighing hoppers 2d, the apparatus as a whole is 
projected radially outwardly requiring a larger installation space. The 
hoppers tend to be contaminated by deposition of the weighed material and, 
hence, have to be cleaned frequently. These hoppers, however, are not easy 
to access because of the presence of the hopper drive units 2g around 
these hoppers. Namely, troublesome work is required to demount the drive 
units at each time of the cleaning and this lowers the efficiency of the 
work. 
The feeder base 2a-1 (See FIGS. 2 thru 4) can translate the vibration of 
the electromagnet 2a-3 effectively to the trough 2a-2 when its weight is 
large. It is, therefore, necessary to increase the weight of the feeder 
base 2a-1 as much as possible. In the distribution supply device 2a in the 
known combinatorial weighing apparatus, therefore, a weight 2a-6 is 
mounted so that the center of gravity is positioned at the rear part of 
the feeder base, i.e. at the end portion of the same close to the 
distribution table 1. The distribution supply devices 2a, each having the 
weights 2a-6, are arranged radially around the distribution table 1 
independently of one another. The condition for the mounting of a 
multiplicity of distribution supply devices 2a around the distribution 
table 1 is that the weights 2a-6 of adjacent feeder bases do not interfere 
each other. For this reason, in the known combinatorial weighing 
apparatus, it is not possible to arrange a multiplicity of distribution 
devices 2a densely around the distribution table 1. Furthermore, since the 
distribution devices 2a are mounted on the support 3 (See FIG. 4) 
independently, the number of supporting members such as coiled springs is 
increased to raise the cost of the weighing apparatus as a whole. 
BRIEF SUMMARY OF THE INVENTION 
Accordingly, an object of the invention is to provide a combinatorial 
weighing apparatus which is improved to reduce the size and to facilitate 
maintenance work such as cleaning. 
Another object of the invention is to provide a combinatorial weighing 
apparatus which is improved to reduce the number of parts and to lower the 
production cost. 
Still another object of the invention is to provide a combinatorial 
weighing apparatus which is improved to increase the power efficiency in 
the hopper drive unit. 
To these ends, according to the invention, there is provided a 
combinatorial weighing apparatus comprising a plurality of pool hoppers 
and a plurality of weighing hoppers arranged radially. The improvement 
comprises that hopper drive units for driving the pool hopper gates and 
the weighing hopper gates are disposed in the spaces defined by the pool 
hoppers and the weighing hoppers or, alternatively, a combinatorial 
weighing apparatus comprising a disc-shaped feeder base common to all 
distribution supply devices, the feeder base being mounted on a hopper 
drive unit, and a plurality of electromagnetic feeders arranged radially 
on the outer peripheral surface of the feeder base at a constant pitch, 
each electromagnetic feeder having a radial trough. 
Other features and advantages of the invention will be apparent from the 
following description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 5 to 7, a conical distribution table 10 is mounted on an 
electromagnetic vibrator 11 and is adapted to be vibrated by the latter 
reciprocatingly and spirally. 
A disc-shaped feeder base 15 is mounted through a plurality of coiled 
springs 14,14 on a support 12 (See FIG. 7) or on a hopper drive unit 22 
(See FIG. 5). The electromagnetic vibrator 11 is carried by the central 
portion of the upper surface of the feeder base. A multiplicity of 
distribution supply devices 16 are arranged radially around the 
distribution table 10 and on the outer peripheral portion of the feeder 
base 15. In the illustrated embodiment, there are provided 10 distribution 
supply devices 16. Each distribution supply device 16 is provided with an 
electromagnet 16a and a leaf spring 16b fixed by suitable means in 
mounting holes 15a,15b, respectively, and a radial trough 16c mounted on 
the electromagnet 16a through a leaf spring 16b. The radially inner end 
portions of the radial trough 16c is positioned below the distribution 
table 10 without contacting the latter. The radially outer end portion of 
the radial trough 16c projects above a pool hopper 17 under which disposed 
is a weighing hopper 18. A multiplicity of weight sensors 20 are arranged 
at a constant pitch on the outer peripheral surface of the frame 19 of the 
weighing apparatus. A collecting chute 21 is disposed at the center of the 
space inside the frame 19, such that the upper open end thereof projects 
slightly above the upper surface of the frame 19. The hopper drive unit 22 
is disposed above the top surface of the frame 19 within the space defined 
by the pool hoppers 17 and the weighing hoppers 18, and is adapted to open 
and close the pool hopper gates 17a and weighing hopper gate 18a through a 
lever mechanism which will be described later. The hopper drive unit 22 is 
supported through members such as a supporting leg 23, supporting base 24 
and so forth. As stated before, a feeder base 15 is mounted on the upper 
surface of the hopper drive unit 22 through a plurality of coiled springs 
14,14. The arrangement is such that, as the material to be weighed is put 
on the distribution table 10 of the combinatorial weighing apparatus 
having the described construction, the material to be weighed is dispersed 
bit by bit radially outwardly from the conical surface of the distribution 
table 10 as a result of a torsional reciprocating vibration of the 
electromagnetic vibrator 11 and is fed to the radial troughs 16c. The 
material is then conveyed through each trough 16c in the direction of the 
arrow 16c by a linear reciprocating vibration of the electromagnet 16a, as 
indicated by an arrow in FIG. 5. The material is then made to drop into 
the pool hopper 17 from the radially outer end of the radial trough 16c. 
The weighed material put into the pool hopper 17 is then passed to the 
weighing hopper 18 and is weighed by the weight sensor 20 annexed to this 
weighing hopper 18. The weight sensors 20 of all weighing hoppers produce 
and deliver signals representing the weights to a combination computing 
device (not shown) which makes a calculation of total weights of the 
material for various combinations of the weighing hoppers to select the 
best combination which approximates the preset target weight most closely 
within a predetermined tolerance. Then, the hopper drive unit 22 operates 
to actuate its lever mechanism to open and close only the weighing hopper 
gates 18a of the weighing hoppers 18 constituting the best combination, 
thereby to discharge the material from these weighing hoppers. The batches 
of the material thus discharged are put into the collecting chute 21 below 
these weighing hoppers 18 and the mass of material is then collected by a 
bucket conveyor which is not shown or put into a packing machine through a 
timing hopper which is also not shown. 
As will be understood from the foregoing description, in the weighing 
apparatus shown in FIGS. 5 thru 7, the hopper drive unit 22 for opening 
and closing the gates 17a,18a of the pool hoppers 17 and weighing hoppers 
18 are disposed in the space surrounded by these hoppers 17,18. It is, 
therefore, possible to reduce the installation space of the weighing 
apparatus as compared with conventional weighing apparatus in which a 
considerably large space is occupied by a plurality of drive units 
arranged around the body of the apparatus. In addition, since a plurality 
of distribution supply devices 16, each including an electromagnet 16a, 
leaf spring 16b and a radial trough 16c, are arranged radially on a common 
single feeder base 15, so that the feeder base can be held stably to 
eliminate the necessity for the weights which are required in the known 
apparatus to transmit effectively the vibration of the electromagnet to 
the trough. 
FIGS. 8 to 11 show the details of the hopper drive unit in the 
combinatorial weighing apparatus in accordance with the invention. 
Referring to these figures, a geared motor 22a is mounted on the central 
portion of the hopper drive unit 22. A sun gear 22c is attached to the end 
of the drive shaft 22b of the geared motor 22a. A plurality of pinions (10 
pinions in the illustrated embodiment) 22d are arranged at a constant 
circumferential pitch around the sun gear 22c in engagement with the 
latter. These pinions 22d are fixed to the ends of the transmission shafts 
22e extending in parallel with the axis of the geared motor 22a. Numerals 
22f and 22g denote cam plates which are secured to each transmission shaft 
22e and spaced by a predetermined distance from each other in the axial 
direction. Clutch/brake mechanisms 22h and 22i are secured to one axial 
ends of the cam plates 22f,22g and fitted around the transmission shaft 
22e. The arrangement is such that these clutch/brake mechanisms 22h,22i 
transmit the torque to respective cam plates 22f,22g in accordance with 
signals coming from a hopper drive controller. Photosensors (not shown) 
are adapted to sense the angular positions of the cam plates 22f,22g. As 
one cycle of operation is completed, the clutches of the clutch/brake 
mechanisms 22h,22i are turned off while the brakes of the same are put 
into effect thereby to repeatedly stop and start the cam plates 22f,22g at 
constant positions. Cam levers 22j,22k are pivotally secured through pins 
22n to predetermined positions of a supporting plate 22m which are 
extended in parallel with the geared motor 22a. These levers 22j,22k are 
provided at their intermediate portions with cam followers 22p,22q which 
are made to contact with the outer peripheral surfaces of the cam plates 
22f,22g, so that the cam levers 22j,22k are adapted to rock in accordance 
with the rotation of the cam plates 22f,22g. Elongated grooves 22r,22s 
(See FIG. 11) are formed in the other ends of the cam levers 22t,22y,22j. 
Retractable levers extending in the direction perpendicular to the cam 
levers 22j,22h have rollers 22w,22x received by the elongated grooves 
22r,22s. The retractable levers are carried by a plurality of lever 
support members 22z on the top surface of a bottom plate 22y (See FIG. 
10). The ends of the retractable levers 22t,22u are connected to the pool 
hopper gate 17a and the weighing hopper gates 18a, respectively. Namely, 
the arrangement is such that the rocking motion of the cam levers 22j,22k 
is changed into linear reciprocating motion of the retractable levers 
22t,22u through rollers 22w,22x, and the pool hopper gate 17a and the 
weighing hopper gate 18a are opened and closed by the linear reciprocating 
motion of the retractable levers 22t,22u. 
In operation, the material to be weighed is charged onto the distribution 
table 10 (See FIG. 5) of the combinatorial weighing apparatus and is 
distributed to the radial troughs 16c from which the material is further 
fed into the weighing hoppers 18 through the pool hoppers 17. The geared 
motor 22a of the hopper drive unit 22 mounted on the center of the body of 
the weighing apparatus is started simultaneously with the start of the 
weighing operation of the weighing apparatus. The driving power of the 
motor is therefore transmitted to the transmission shafts 22e through the 
sun gear 22c and the pinions 22d, thereby to rotatingly drive the 
trnasmision shafts 22e. As the material to be weighed is conveyed through 
the radial troughs 16c in the direction of the arrow shown in FIG. 5, two 
clutch/brake mechanisms 22h,22i on each transmission shaft 22e of the 
hopper drive unit 22 are made to operate in accordance with the signal 
coming from the hopper drive control device thereby to transmit the torque 
of the transmission shaft to the cam plates 22f,22g connected to one end 
of these clutch/brake mechanisms. Then, the cam levers 22j,22k having the 
cam followers 22p,22q always contacting the outer peripheral surface of 
the cam plates 22f,22g are made to rock around the pins 22n. In 
consequence, the retractable levers 22t,22u, connected to the ends of the 
cam levers 22j,22k through rollers 22w,22x, are made to reciprocate in the 
direction perpendicular to the direction of the cam levers 22j,22k. The 
linear reciprocating motion of the retractable levers 22t,22u is ensured 
by the presence of the support members 22z disposed at predetermined 
portions along the lateral sides of these levers. In consequence, the pool 
hopper gates 17a and the weighing hopper gates 18a connected to the ends 
of the retractable levers 22t,22u are made to open and close in accordance 
with the linear reciprocating motion of the retractable levers 22t,22u. As 
a result, batches of the material to be weighed, dropped from the ends of 
the radial troughs 16c, are supplied into the pool hoppers 17 and the 
batches of material which have been supplied to the pool hopper 17 are 
dropped into the weighing hopper 18 beneath the pool hopper 17. Then, 
signals representing the weights of batches of material in respective 
weighing hoppers are delivered by the weight sensors 20 to the combination 
computing device in which computation of total weight is computed to 
select the best combination which provides a total weight closest to the 
preset target weight. Then, the clutch/brake mechanisms 22h,22i are 
operated on the basis of the selected combination, so that the gates 17a 
and 18a of the selected pool hoppers 17 and weighing hoppers 18 
constituting the best combination are made to open by the linear 
reciprocating motion of the retractable levers 22t,22u. The weighed 
material is then dropped from each of these weighing hoppers into the 
collecting chute 21 under these hoppers and is further collected into a 
bucket conveyor which is not shown. Thereafter, the weighing hopper gates 
18a are closed while the pool hopper gates 17a are opened to put the 
weighed material into the weighing hoppers 18. On the other hand, as one 
cycle of a weighing operation is completed, the cam plates 22f,22g of the 
hopper drive unit 22 are made to stop at predetermined positions because 
the clutches of the clutch/brake mechanisms 22h,22i are turned off while 
the brakes are put into effect as explained before. Then, the next cycle 
of weighing peration is started in accordance with the signal coming from 
the hopper drive control device. 
The use of clutch/brake mechanisms in the hopper drive unit is not 
exclusive. For instance, a similar effect is obtained by the use of a 
stepping motor, pneumatic cylinder, hydraulic cylinder or the like in 
place of the clutch/brake mechanism. 
FIG. 12 is a front elevational view of a hopper opening and closing 
mechanism in accordance with the invention. FIGS. 12 and 13 are a 
partly-sectioned plan view and a partly-sectioned side elevational view of 
the hopper opening and closing mechanism shown in FIG. 12. Although the 
following description is made with specific reference to the opening and 
closing of the pool hopper gate 17a, it is to be understood that the same 
mechanism can be equally applied to the opening and closing of the 
weighing hopper gate 18a. 
Referring to these figures, a rotary lever 51a constituting the opening and 
closing lever mechanism 51 has one end which is bent in a form like C and 
pivotally secured by a pivot bolt 51c to a bracket 51b fixed to a side 
wall of the pool hopper 17. A reference numeral 51d (See FIGS. 13 and 24) 
denotes a bracket fixed to the edge of the side wall of the pool hopper 
17, 51e denotes a rocker lever pivoted by a pivot bolt 51f attached to the 
bracket 51d to stand upright therefrom, and 51g denotes a connecting lever 
pivotally secured to the end of the rocker lever 51e and the other end of 
the rotary lever 51a by means of the pivot bolts 51h,51i. Mounting bracket 
51j are attached to the side walls of the pool hopper gate 17a. The pool 
hopper gate 17a is swingable around pivot bolts 51k by means of which the 
mounting brackets 51j are fixed to the pool hopper gate 17a. A reference 
numeral 51m denotes an opening lever which is pivotally connected at its 
one end to the mounting bracket 51j through a pivot bolt 51n and at the 
other end pivotally to a pivot bolt 51 i by which the rocker lever 51e and 
the connecting lever 51g are connected to each other. 
A reference numeral 51p denotes a fixing lever secured at one end to the 
pivot bolt 51f for rocker lever 51e and at its other end to the pivot bolt 
51k for securing the pool hopper gate 17a. A reference numeral 51q 
designates a spring connected between an intermediate portion of the 
rotary lever 51a and the side wall of the hopper 17, so as to normally 
bias the rotary lever 51a in the clockwise direction. A reference numeral 
51r designates a stopper fixed to the side wall of the hopper 17. When the 
rotary lever 51a is rotatively biased in the clockwise direction by the 
force of the spring 51q, the connection between the rotary lever 51a and 
the connecting lever 51g is stopped by the stopper 51r so that any further 
rotation of the rotary lever 51a is prevented. In this state, the rotary 
lever 51a and the connecting lever 51g form a continuous straight line. A 
reference numeral 50s designates a rocker member pivoted to and suspended 
from the pivot bolt 51c for the rotary lever 51a. This rocker member 51s 
is provided at its end with a roller 51t. Each roller 51t is disposed to 
oppose the retractable levers 22t,22u. Instead of suspending downwardly, 
the rocker member 51s may protrude upwardly (See FIG. 12A). 
In operation, as the material to be weighed is put into the pool hoppers 17 
or the weighing hoppers 18, the hopper drive unit 22 (See FIGS. 8 to 11) 
starts to operate and the retractable lever 22t is moved ahead to bring 
the end 22t' of this lever into contact with the roller 51t of the 
downwardly suspended rocker member 51s thereby to press and move the 
roller 51t. In consequence, the rocker member 51s is swung 
counter-clockwise around the pivot bolt 51c, so that the rotary lever 51a 
is rotated counter-clockwisely overcoming the force of the spring 51q by 
an angle equal to that of the rocker member 51s. As a result, the 
connecting lever 51g, which is rotating around the pivot bolt 51i is 
pulled by the rotary lever 51a and, at the same time, the rocker lever 51e 
is made to rock counter-clockwise around the pivot bolt 51f. In 
consequence, the point of connection between the rocker lever 51e and the 
connecting lever 51g is moved inward (See FIG. 12B). As a result, the 
mounting bracket 51j is rotated clockwise around the pivot bolt 51k so 
that the pool hopper gate 17a fixed to the same shaft as the mounting 
bracket 51j is swung in the opening direction thereby to open the pool 
hopper 17 (See FIG. 12B). As the material to be weighed is discharged from 
the pool hopper 17 which is thus opened, the retractable lever 22t is 
retracted so that the roller 51t is relieved from the pressing force 
imposed by the rocker member 51s and, accordingly, the rotary lever 51a is 
rotated clockwisely around the pivot bolt 51c by the force of the spring 
51q until it is stopped by the stopper 51r thereby to displace the 
connecting lever 51g outwardly. In consequence, the rocker lever 51e is 
rotated clockwisely around the pivot bolt 51f so that the point of 
connection between the rocker lever 51e and the connecting lever 51g is 
displaced outwardly thereby to pull the opening lever 51m outwardly. As a 
result of this motion of the opening lever 51m, the mounting bracket 51j 
is rotated counter-clockwise around the pivot bolt 51k so that the pool 
hopper gate 17a fixed to the same shaft as the mounting bracket 51j is 
swung in the closing direction to close the pool hopper 17 to reset to the 
initial state shown in FIG. 12A. This operation is repeated cyclically to 
open and close the pool hopper gate 17a. 
In the described embodiment, the rocker member 51s is suspended downwardly. 
This, however, is not exclusive and the rocker member 51s may be mounted 
to protrude upward. In such a case, the arrangement may be such that the 
end 22t' of the retractable lever 22t is formed into a hook-like shape and 
the pool hopper gate 17a is opened and closed by pulling the roller 51t 
inwardly. 
As will be understood from the foregoing description, according to the 
invention, there is provided a combinatorial weighing apparatus in which a 
hopper drive unit for effecting the opening and closing motions of the 
pool hopper and the weighing hoppers is disposed at the central portion of 
the body of the weighing apparatus, within the space substantially 
surrounded by the pool hoppers and weighing hoppers, to permit all 
weighing sections to make a common use of a single drive unit including 
the prime mover such as a geared motor. The combinatorial weighing 
apparatus of the invention, therefore offers various advantages such as 
reduction in number of parts and, hence, a reduction in the cost, as well 
as improvement in the power efficiency. Furthermore, the mounting of the 
hopper drive unit makes it possible to dispose the pool hoppers and the 
weighing hoppers at the radially outermost portion of the apparatus as a 
whole, so that the hoppers are easy to access for demounting to permit 
easy maintenance work such as cleaning. In addition, since the space which 
is occupied by a plurality of independent drive units in the known 
apparatus is saved, the apparatus as a whole can be made compact and the 
cost is reduced correspondingly. 
Furthermore, since a plurality of electromagnetic feeders carrying radial 
troughs are arranged radially on the upper surface of a disc-shaped feeder 
base which is common to all distribution supply units, it is possible to 
eliminate the weight which is required in the conventional apparatus for 
each distribution supply device and, hence, to arrange a multiplicity of 
distribution supply devices at a higher density. The use of a single 
common disc-shaped feeder base further permits a reduction in the number 
of parts such as coiled springs for mounting the feeder base on the 
support of the body of the weighing apparatus, contributing a further 
reduction of the production cost advantageously.