US2138315A - Pulsating jig - Google Patents

Description

Nov. 29, 1938. G, A. VISSAC 2,138,315

PULSATING JIG Filed July 26, 1957 4 sheets-sheet 1 INVENTORI.

Gusfave Andre V/SSaC.

ATTOR N EY.

Nov. 29, 1938. G A, vlssAc 2,138,315

PULSATING JIG Filed J u1y'26, 1957 4 Sheets-Sheet 2 INVENTOQ Gusfm/eA/vdr Vl'ssac.

. ATTQRNEY G. A. VISSAC PULSATING JIG Nov. 29, 1938.

Filed July 26, 1957 4 Sheets-Sheet 3 NV E N TO R Gusfa veA/vare V/ssac.

BY 5 a ATTORNEY Nov. 29, 1938. G, A, VISSAC 2,138,315

" PULSATING JIG Filed July 26, 1937 4Shets-Sheet 4 i E B INVENTOR Gusfave g g/e Vl'ssac.

ATTORNEY Patented Nov. 29, 1938 UNITED STATES ATNT OFFICE 11 Claims.

This invention relates to a jig in which water pulsations are used for the separation, concentration or cleaning of coal or minerals.

Water pulsations are generally obtained in jigs by mechanical means, such as by moving sieves or screens; or in fixed sieve jigs, by pistons or swinging plates. In other types of jigs, however, the water pulsations are obtained by air puffs on the top of air chambers. In these last mentioned types of jigs, new air may be alternately admitted and released, as in the Baum types, or the same air may be compressed and depressed by water hammers in the water feed systems, as in the Richards types.

Each of the above types has its advantages and disadvantages. Jigs with mechanically produced pulsations give good results but the various working parts wear away rapidly and, therefore, must be frequently renewed to ensure constant results. These types of jigs generally have heavily packed beds which restrict the output per unit of area.

Jigs using air pulsations as a medium for producing water pulsations are' more flexible and more adapted to cover a wide range of sizes and low specific gravities, but air is soluble in water and, consequently, constant results are difficult to obtain, particularly when working at high specific gravity separations in which comparatively high air pressures are' employed.

The object of this invention is to combine the above features with certain special novel mechanisms, to provide a jig capable of producing, by means of simple and readily accessible adjustmerits, the following results:-

1. Any shape and intensity of water surge that may be required to suit the various sizes and gravities of the products to be treated.

2. Any number of surges per minute that may be suitable to the size of the products and the required outputs.

3. Permanent conditions, independent of possible variations, in the amount of air dissolved in the Water feed; in wear and tear of moving parts; in variations of the characteristics of the electrical current supplying motive power.

In this jig, pulsations are produced mechanically by a swinging plate, such as used in Stutz (U. S. Pat. No. 242,711), but in the present device the plate is assisted by air pulsations.

One of the chief problems in a pulsating jig is to realize the best and most efficient transformation of a continuous flow of water, as delivered by a feeding pipe, into an alternating flow, corresponding to the alternating pulsations of the jig. This is a well known pumping problem and its solution is found in air chambers capable of absorbing the excess water at the period of low demand and restoring it at the period of high demand. The volume of the air chamber, its shape, the amount of air, maximum and minimum volumes and pressures of the air are easily calculated by well known formulae, in the case of a definite problem.

Generally speaking and forthe purposeof proper air control, it is customary to provide air chambers having a volume at least six times greater than the volume of the water to be stored. In case of very low air pressures, however, this volume is reduced to three times, and for very high pressures, twenty-two times the volume is necessary.

In the case of a pulsating jig, flexible enough to handle a wide diversification of specific gravities, separation and. outputs, the data for the establishment of the required air chamber vary widely, and no simple uniform solution is possible. The volume of the air chamber must be such as to allow for the storage of the available water in the pulsating period of no demand from the jig.

But the range of air pressures involved must always'be small, for, if not, air is liable to be absorbed or liberated by the water and, therefore, the volume of air would change constantly, and the air chamber would not be capable of giving the perfect control expected of it.

The various systems of air controls, well known in pumping practice, are never sufficiently accurate nor reliable, to be depended upon in these devices, due to the sharp surges encountered and to the dirty. condition of the water used.

The present invention consists essentially of a casing having an air chamber therein; means for continuously feeding water to the chamber from a suitable source of supply, such as a head tank or pump, said air chamber being adapted to store water therein and being shaped to receive an increased amount of water without unduly increasing the air pressure therein, a swinging plate for producing water pulsations in the jig and means for feeding water alternately on each side of the plate, as it swings back and forth, in such a manner as to assist rather than oppose the swinging motion, as more fully described in the following specification and illustrated in the accompanying drawings, in which Figure 1 is a vertical sectional view of the jig,

Figure 2 is an end elevation partly in section, of the jig, with the source of power removed,

Figure 3 diagrammatically illustrates the old form of air chamber,

Figure 4 diagrammatically illustrates the air chamber of the present invention,

Figure 5 is a plan view of the jig, showing the source of power and the drive mechanism,

Figure 6 is a fragmentary side elevation of the jig showing the drive mechanism for the swinging plate, and

Figures 7 and 8 graphically illustrate typical surges produced in the jig.

Referirng more particularly to the drawings, E5 is an open casing having side walls I! and !2, end walls l3 and i4 and a curved bottom I5. The side walls H and i2 extend downwardly beyond the bottom l5 to form supports for the device. A closed air chamber 56 is formed in the casing ii at one end thereof. The walls ll, l2 and [3 of the casing Ill form three walls of the chamher it and a sloping partition ll, extending transversely of the casing, forms the other wall of said chamber, The air chamber has a top H! and a bottom N which tapers downwardly to an outlet 25 in which is mounted a suitable control valve 2!. This control valve 25 may be any suitable well known type of valve but for the purpose of illustration a butterfly valve is shown mounted on a shaft 22 which extends beyond the wall it of the casing l5 and has sprockets 23 and 26 mounted thereon.

A further partition 25 extends downwardly within the casing) and terminates at a point 25 spaced from the bottom 15. A shaft 2? extends transversely of the casing adjacent the lower end of the partition 25 and has mounted thereon a curved swinging plate 28. The plate 28 extends downwardly to a curved plate 29 spaced from the bottom E5 to form a by-pass passage 3!! therebetween. The plate 28 may swing from a point 36 to a point 32 on the plate 29 (see Fig. 1). al-

' though the limit of its swing may be increased or lessened if desired. For the sake of convenience, the area through which the swinging plate 28 moves, in travelling from one extreme position to the other, as shown in Figure 1, will be known as the pulsating chamber 33.

A feeding chamber 3 is formed between the swinging plate 28 (in its uppermost position) the bottom of the air chamber l6 and a bottom 35 which tapers downwardly to an outlet 36 in which is mounted a suitable valve 31. The outlet 35, which is somewhat larger than the outlet 20 of the air chamber, communicates with the passage 38. Plates 38 extend downwardly and outwardly from the outlet 36 to the side walls of the casing H3 within the passage 35. As in the case of the valve 2!, the valve Bl may be any suitable well known type and for the purpose of illustration it is shown in the form of a butterfly valve mounted on a shaft 39 which extends beyond the wall ll of the casing l5 and has a sprocket 46 mounted thereon. Gate control valves 42 and 43 are mounted in the outlets 25 and 35, respectively, in order to control the flow of water through these outlets. The valves 52 and 43 are mounted on shafts 4 3 and 45 journalled in the walls of the casing ill and having operating handles 45 and ll on their outer ends.

The area between the partitions I1 and 25 and above the feeding chamber 34 will hereinafter be known as the auxiliary air chamber 48 while that area in the casing it) beyond the pulsating chamber 33 will be known as the hutch 5D.

A water supply pipe 5! leading from a head tank or pump (not shown) and having a regulating valve 52 therein, extends through the end wall l3 of the casing into the air chamber IS. A screen or sieve 53 extends and slopes downwardly from the partition 25 to the end wall I4 of the casing, immediately above the hutch 50. The raw coal or mineral is supplied to the jig by a chute 5 which coal or mineral is directed on to the screen 53 by a baffle plate 55. The clean coal or lighter materials pass out of the casing l5 through a discharge chute 56 formed at the top thereof and the stone or heavier materials remain on the screen and pass out of the casing through an opening 57 in the end wall id just above the screen 53. A gate 58 is provided to regulate the size of the opening 5] and a chute 65 extends from said opening into a refuse elevator 5! situated beside the casing Ill. The curved bottom i5 is perforated or slotted at 62 and a chute 83 extends from said perforations or slots to the elevator 61.

A pair of supports 64 extend beyond one end of the casing Hi and carry a platform 65 upon which is mounted a suitable source of powerjBB, such as an electric motor, gasoline engine, Diesel engine or the like. A sprocket 61 mounted on the power shaft 68 of the source of power 66, is connected by a chain '38 to a sprocket 'H mounted on a shaft '32 journalled in standards 13 projecting upwardly from the supports 64. A sprocket M mounted on one end of the shaft 12 is connected by a chain 15 to the sprocket 24 of the valve 2! and the sprocket 23 is connected by a chain E5 to the sprocket 4B of the valve 31.

The end of the shaft 2? of the swinging plate 28 extending beyond the wall l2 of the casing, has a bell crank lever ll mounted thereon, said ell crank lever being formed with arms 18 and i9 and having a counterweight 80 slidably mounted on the arm l9. The arm 18 of the bell crank lever is pivotally connected at 8| to an eccentric rod 82 which in turn is formed at its opposite end with an eccentric sleeve 83 fitted over an eccentric 84 mounted on the shaft 12.

Withthis construction, the eccentric 84 and the sprocket M are rotated by the motor or engine 66 and a recipricating motion is imparted to the swinging plate 28 by the eccentric 84 through the eccentric rod 82 and the bell crank lever 11. The extent of movement of the plate 28 may be regulated by using eccentrics having different centres, or by using an adjustable eccentric. The sprocket l4 rotates the sprockets 24, 23 and and, consequently, the valves 2| and 31. The timing of the rotation of the valves 2| and 3'! and the reciprocating of the plate 28 is such that the valve 2! is normally open and the valve 3'! is normally closed during the downward or surgeproducing movement of the plate 28. The valve 21 is closed and the valve 3'! is open during the return movement of said plate.

The general operation of the jig is as follows: water is supplied to the air chamber l5 through the pipe 5!, whence it passes through the opening 25 into the feeding chamber 34. The water then flows through the opening 36 and the passage 31! into the hutch 55 and the pulsating chamber 33. The swinging plate 28 forces the body of water in a surge from the pulsating chamber through the hutch 5B, the screen 53 and out of the jig through the chute 56. The material to be separated, concentrated or cleaned, such as, for example, raw coal, is supplied to the casing ill through the chute 54 and is directed on to the screen 53 by the baffle plate 55. The surges of water from the pulsating chamber are reversed so that the valve 3? is open.

wash the comparatively light coal out through the chute 56 while the large heavy materials, such as stone, remain on the screen whence they pass through the opening 57 along the chute 60 into the refuse elevator 6!. Any of the heavier materials small enough to pass through the screen drop down on to the curved bottom of the casing and eventually pass through the perforations or slots 62 along the chute 63 into the refuse elevator.

As stated above, the valve 2! is open and the valve 3? is closed during the forward or surgeproducing movement of'the swinging plate 28 and the'positions of these valves are reversed during the return movement of said plate. When the valve 2| is closed, the water running into the air chamber l6 compresses the air therein. This takes place during the return movement of the swinging plate. As the valve 2! opens, the valve 3'! closes and the compressed air forces the water through the opening 26 into the feeding chamber. The pressure of the water against the back of the swinging plate assists it in its forward movement. As the swinging plate starts its return movement, the positions of the valves The return movement of the plate forces the water from the feeding chamber through the opening 36 and the by-pass passage 39 into the hutch 5B whence it is drawn into the pulsating chamber 33 by the vacuum created by the return movement of the plate. The water entering the pulsating chamber assists the return movement of the plate and prevents any appreciable suction being created in the hutch. This return movement of the swinging plate is also assisted by the counter weight 86 of the bell crank lever ill. The Water in the feeding chamber compresses the air in the auxiliary air chamber 43 at the beginning of the return movement of the swinging plate. The compressed air of the auxiliary air chamber will assist the flow of the water through the opening 36 when the valve 3? is open.

However, the main purpose of the auxiliary air chamber is to absorb possible pressure shocks and suction shocks, during the forward and return movements respectively, of the swinging plate. This auxiliary air chamber acts in a similar manner to the well known suction chamber on the suction pipe of a single acting pump.

Figure 3 diagrammatically illustrates the old type of air chamber and Figure 4 diagrammatically illustrates the new type of chamber according to the present invention. In the old type of air chamber, with vertical walls, an increase in the volume of water contained therein, say, for example, from the level A-A to the level B-B, would increase the pressure of the air a certain amount, while in the new type of air chamber 15 with its downwardly converging sides, the same increase in volume would only raise the water level from the level CC to the level D-D resulting in a smaller increase in the air pressure. In other words, if we take a certain volume of air in both air chambers, as the product pressure by volume is constant (Avogadros law, p22=constant), a smaller corresponding reduction in volume will naturally cause a smaller increase in pressure. This makes it possible toobtain increased surges, requiring increased water consumption, without the same corresponding increase of air pressure and without the greater corresponding absorption of air by water ordi narily resulting from higher pressures.

The swinging plate 28 extends transversely of the jig and "is curved to ensure proper distribution of water tothe screen 53 during each forward movement of the plate. The swinging plate empties the pulsating chamber during each stroke, the volume of water involved during each stroke being equal to the volume defined by the sides of the casing in, the plate 28 and the swinging plate in its extreme positions.

While the valve 2! has been described as being open and the valve 3'! closed during the forward movement of the swinging plate and the positions of these valves reversed during the return movement of said plate, it is to be understood that the-operation of these valves may be advanced or retarded to suit different cleaning problems. Such valves are common to all Richards type jigs (U. S. Pat. Nos. 901,474 and 901,475). However, in these types of jig, the air chamber also being the pulsating chamber, the tendency has been to use long narrow openings substantially co-extensive with the screen plate and substantially the length of the plate. This was done for the purpose of spreading the Water pulsations evenly over the screen plate but, as will be seen, such openings are very inefiicient and economically undesirable.

In the present device where air chambers are solely for feeding purposes, the most efficient type of opening can be used without beingtied down by any condition of pressure distribution. All the valve openings can now be located at the most favourable point for proper water guidance and air seal. All the valve openings are simply calculated according to well known formulae of hydraulics, and established to give the desired area of opening, with the minimum perimeter.

Taking valve 2! for example, this valve must deliver water from the air chamber IE, to the feeding chamber 3d under certain conditions:

Assume the volume of water consumed by the jig to be 4 cu. ft. per second, the forward stroke and return stroke being of the same duration, the feeding period will be half time. We must then feed at the rate of 8 cu. ft. per seconds For ideal conditions, minimum waste of power, minimum leakage of water, mostly with loose fittings, the water must be delivered in time and quantity, behind the swinging plate 28, so as to follow its motion and to fill its vacuum gradually. With well guided openings, we can neglect restriction coefiicients, and use the formula of flow:

Q=S /2gh.

with 62:53 cu. ft. 9:32 ft.

These figures correspond to a jig 4 ft. 6 inches wide, so that, with a valve opening of the full length of the jig, as advocated in various prior devices, the width of the opening would be in inches hence 4 4.5 .S.31nch.

Obviously this would be too small, impractical, and inefficient. All losses through friction and leakage are proportionate to the perimeter of the opening. 7

A long narrow opening such as advocated by Lide (U. S. Pat. Nos. 17,272; 1,491,870 and 2,027,597) or Karl J. Meyer (German Pat. No. 91,570) would give a perimeter of opening equal to (4.5 12+.8) 2 109.6 inches. In the present device, using an almost square opening, the dimensions C of the sides will be:

or a total perimeter of 26.8 inches, as against 109.6 inches.

The valve 3'! is calculated in the same manner. All valves are calculated to suit the maximum water consumption anticipated, then the final opening to suit the various conditions is adjusted by the gate control valves 42 and 43.

If possible a circle will be the best area of opening; for construction facilities, the opening is usually made as wide as possible, and of a length such as to include the maximum value of opening as established by the above method of calculation.

The ideal jig must make available a wide variety of shapes of surges with the simplest possible adjustments. These shapes are illutrated and registered, as for example, by a pen attached to a float on the top of the water in the jig casing, said pen tracing a diagram on a paper moving at a constant speed, representing time.

Figures 7 and 8 represent two typical surges. In these figures, the lines 86 and 81 represent the float displacements in inches and the lines 88 and 89 represent the time in seconds, Figure 7 illustrates a short fast pulsation, with a slow rising surge, a flat top and a slow descent. Such surges are particularly adapted to small sizes of particles, and low specific gravity separations. In D-E the water is moved by the surge plate 28 alone; at E the valve 3'! opens, adding some water, and giving the rise EF. At F the plate 28 swings back, valve 37 is still open, and not only refills the chamber 33, but delivers a certain amount of extra water into the hutch 50. At G valve 31 closes, plate 28 is still swinging back,

and the chamber 33 will fill with water from the hutch 58, causing suction G-H.

Figure 8 illustrates a long slow pulsation, with a sharp rise, a fast drop, followed immediately by a sharp suction, which is particularly suitable for the separation of large pieces and for high specific gravity separations. The maximum of water is obtained at the start of the forward stroke, by having the valve 31 open at that time to add water, through the passage 30, to water moved by the plate 28, resulting in the sharp surge I-J; then as the valve 37 closes, the up surge drops from J to K. At K, when the plate 28 starts its return swing, valve 31 which has been retarded is not opened yet, and a sharp suction K L is produced. Then as the valve 31 opens at L, a quiet settling period MN follows.

From these two examples, it can be seen that an infinite varietyof surges can be produced.

The opening of the valves 2| and 31, on the whole, is such, that the motion of the water under elastic pressure from air chambers l6 and 48, facilitates the motion of plate 28, and does not call for tight fittings of these valves nor of said plate. This feature not only saves wear and tear, but provides during most of the return stroke, a certain amount of positive Water flow, as shown in the diagrams in Figures 7 and 8, the value of which is emphasized in U. S. Pat. No. 2,055,161.

By reason of the loose fitting of all the mechanical parts, and of the combined action of air and water which always assists, but never opposes the motion of the swinging plate 28, a 5 H. P. motor may be used on the main drives, in jigs capable of handling tons of raw coal per hour. An advantage of such small power units, is the possibility of using variable speed drives, whose importance, in such pulsating water motions, has been demonstrated in the applicants co-pending U. S. application S. N., 69,187. In addition, such a variable speed drive gives further variations in producing the proper surges most suitable to each particular concentration or cleaning problem.

Variable speed of pulsations, for a given volume of water, controls variable surge intensities. With a variable speed of pulsations per minute and a certain volume of water per pulsation the output may be controlled.

The speed and volume of the water supply is controlled by the valves 52 and 2|. The magnitude and speed of the pulsations or surges is controlled by the adjustable eccentric 84 which drives the swinging plate 28.

The timing of the valve 2 l, advanced or retarded, in relation to the pulsating motion of the plate 28, results in sharp or slow, rise or descent, of the up or down water surges. The timing of the valve 87, controls the time of suction at the start or at the end of each stroke of the swinging plate.

The air pressure in air chambers l6 and 48 is used here only as auxiliary motive power, and does not need to be accurately controlled. This overcomes the most serious failing of the Richards type jigs.

The swinging plate 28, following the motion of the water, as controlled and distributed by the present system of valves and air chambers, disperses the water evenly under the screen 53, but does not require a close fit. This eliminates the main disadvantage of the piston type jig.

Another interesting feature of this invention, lies in the fact that when suction is created through the screen 53, during the return stroke of the plate 28, the corresponding water displaced is stored in the auxiliary air chamber 48, making it available for the next forward stroke. This is a great improvement over all types of Richards jigs, Where suction is produced by draining a certain amount of water from the hutch since this water is lost to the jig and has to be pumped back into the system.

Various modifications may be made in this invention without departing from the spirit thereof or the scope of the claims, and therefore the exact forms shown are to be taken as illustrative only and not in a limiting sense, and it is desired that only such limitations shall be placed thereon as are disclosed in the prior art or are set forth in the accompanying claims.

What I claim as my invention is:

1. A jig comprising a casing, a hutch formed in said casing, screening means over the hutch, a swinging surge plate mounted at one side of the hutch, means for reciprocating the plate, an air chamber having an outlet communicating with the casing, means for supplying a constant fiow of water to the air chamber from a suitable source of supply, and means for positively and alternately closing and opening the outlet of the air chamber positively to control the fiow of water therefrom, said air chamber being adapted to store water when the outlet therefrom is closed.

2. A jig comprising a casing, a hutch formed in said casing, screening means over the hutch, a swinging plate mounted at one side of the hutch, means for reciprocating the plate,an air chamber having an outlet communicating with the casing on one side of the plate, said chamber being relatively large at the top and tapering downwardly to the outlet opening, means for supplying a constantfiow of water to the air chamber from a suitable source of supply, said air chamber being adapted to store increased volumes of water without correspondingly increasing the air pressure therein and valve means in the outlet of the air chamber for controlling the fiow of water therefrom to assist the movement of the swinging plate.

3. A jig comprising a casing, a hutch formed in said casing, screening means over the hutch, a swinging surge plate mounted at one side of the hutch, means for reciprocating the plate, an air chamber in the casing, means for supplying a flow of water to the air chamber from a suitable source of supply, said air chamber being relatively large at the top and tapering downwardly to an outlet opening to store increased volumes of water without correspondingly increasing the air pressure therein, means operated independently of the swinging plate for feeding water from the air chamber alternately on each side of the swinging plate and means for timing the feeding of said water to assist the movement of the plate by constantly feeding the water in the direction of movement of the plate continually to establish substantially the same pressure on each side thereof.

4. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, a swinging plate mounted at one side of the hutch, means for reciprocating the plate, an air chamber in the casing, a feeding chamber between the air chamber, and the swinging plate, said air chamber having an outlet opening communicating with the feeding chamber, a valve mounted in the outlet opening of the air chamber, and means independent of the swinging plate for operating the valve to deliver water from the air chamber to the feeding chamber as the swinging plate is moving in one direction and means for feeding the water from the feeding chamber to the other side of the plate as said plate moves in the opposite direction whereby said water assists the movement of the plate in either direction.

5. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber, a pulsating chamber adjacent the feeding chamber, a swinging plate mounted in the pulsating chamber, means for reciprocating the swinging plate, means for delivering water from the air chamber to the feeding chamber only during the movement of the plate in one direction, and means independent of the plate for delivering water from the feeding chamber to the pulsating chamber during the return movement of the plate, said plate being adapted to distribute the water in surges from the pulsating chamber to the screening means.

6. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber, a pulsating chamber adjacent the feeding chamber, a swinging plate mounted in the pulsating chamber means for reciprocating said plate, a passage between the feeding chamber and the pulsating chamber, said feeding chamher having an outlet opening communicating with the passage, means for adjusting the area of the outlet opening, means for delivering water from the air cham er to the feeding chamber only during the movement of the plate in one direction, a valve in the outlet opening of the feeding chamber, and means for operating the valve to deliver water from the feeding chamber through the passage to the pulsating chamber during the return movement of the plate, said plate being adapted to distribute the water in surges from the pulsating chamber to the screening means.

7. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber, a pulsating chamber adjacent the feeding chamber, a swinging plate mounted in the pulsating chamber, means for reciprocating the swinging plate, a valve mounted in the bottom of the air chamber for controlling,

the flow of water therefrom to the feeding chamber, a valve in the bottom of the feeding chamber for controlling the flow of water therefrom into the pulsating chamber,.means for operating said valves, an auxiliary air chamber above the feeding and pulsating chambers for absorbing pressure and suction shocks produced in the feeding chamber by the movement of the swinging plate when either of the valves is closed, said plate being adapted to distribute the water in surges from the pulsating chamber to the screening means.

8. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing having an outlet opening in the bottom thereof, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber having an outlet opening in the bottom thereof, a pulsating chamber adjacent to and communicating with the feeding chamber, a swinging plate mounted in the pulsating chamber, means for reciprocating said plate, a valve mounted in the outlet of the air chamber for controlling the flow of water therefrom to the feeding chamber, a valve in the outlet opening of the feeding chamber for controlling the fiow of water therefrom to the pulsating chamber, and means for opening and closing said valves alternately to each other to deliver water alternately on each side of the swinging plate, said plate being adapted to distribute the water in surges from the pulsating chamber to the screening means.

9. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing having an outlet opening in the bottom thereof, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber having an outlet opening in the bottom thereof, a pulsating chamber adjacent to and communicating with the feeding chamber, a swinging plate mounted in the pulsating chamber, means for reciprocating said plates a valve mounted in the outlet opening of the air chamber for controlling the flow of water therefrom to the feeding chamber, a valve in the outlet opening of the feeding chamber for controlling the flow of water therefrom to the pulsating chamber,

means for opening and closing said valves alter- 75 nately to each other to deliver water alternately to each side of the swinging plate, said air chamber valve being open during the forward movement of the plate and the feeding chamber valve being open during the return movement thereof, means for selectively advancing and retarding the operation of the valves in relation to the movement of the plate to regulate the suction through the screen during the return movement of the plate and to store water in the hutch for the next forward stroke of the plate.

10. A jig comprising a casing, a hutch formed in the casing, screening means over the hutch, an air chamber in the casing, means for supplying a flow of water to the air chamber from a suitable source of supply, a feeding chamber adjacent the air chamber, a pulsating chamber adjacent the feeding chamber, a swinging plate mounted on a shaft in the pulsating chamber, said air chamber being adapted to deliver water to the feeding chamber, means for delivering the water from the feeding chamber to the pulsating chamber alternately on each side of the swinging plate, a bell crank lever mounted on the shaft of the swinging plate, an eccentric arm connecting one arm of the lever to an adjustable eccentric, said eccentric being rotated by a suitable source of power to reciprocate the swinging plate through the bell crank lever, and a counter weight mounted on the other arm of the lever adapted to equalize the power operating the swinging plate.

11. A jig comprising a casing, a hutch formed in said casing, screening means over the hutch, a swinging plate mounted at one side of the hutch, means for reciprocating the plate, means for supplying a flow of water to the casing on one side of the plate. a by-pass communicating with the interior of the casing on each side of the plate, valves in the casing for controlling the flow of water therein, means for controlling the operation of said valves to cause the water to flow against the plate when it is moving in one direction and to flow through the by-pass to the other side of the plate when it is moving in the opposite direction, whereby the movement of the plate is assisted by constantly feeding the water in the direction of movement of the plate continually to establish substantially the same pressure on each side thereof.

GUSTAVE ANDRE VISSAC'.

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