Патент USA US2132380код для вставки
Oct. 11, 1938. J. c. ATTWOOD 2,132,380 JIG Filed March 4, 1935 5 SheetS-Sheet l D\SCHARGE. f/vvE/v TOE’: I John G. Affwooaf. A TT'X Oct... 11, 1938. 2,132,380 I J. G. ATTwooD Filed March 4, 1935 5 Sheets-Sheet 2 . [An/EN TOR.‘ ‘Jo/7n G AffWOOO', ATT'Y Oct. 11, 1938. J. G. ATTWOOD JIG Filed March 4, 1935 2,132,380 5 Sheets-Sheet 5 [/VVENTOE'. John G H/‘fwooa? BY ATT'Y Oct. 11, 1938. J. G. ATTWOOD 2,132,380 JIG Filed March 4, 1955 5 Sheets-Sheet 4 f/VVENTOR . John G H7’7‘wooof BY ATT'X Patented 11, 1938 _ 2,132,380 ~ UNITED STATES PATENT I OFFICE 2,132,380 HG John G. Attwood, Columbus, Ohio, assignor to The Jeiirey Manufacturing Company, a corporation of Ohio Application March 4, 1935, Serial No. 9,147 4 Claims. (01. 209-496) This invention relates to a jig and particularly to an automatic means for controlling the dis charge of refuse from a jig. An object of the invention is to provide a new 5 and improved automatic means for controlling the discharge of refuse from a jig whereby a ref } use bed of substantially constant depth may be obtained. ‘ Another object of the invention is to provide 10 an improved ?oat for an automatic refuse dis charge mechanism of a jig, which ?oat is sub stantially “?sh”-shaped. provide a new and " .nproved automatic means for is controllingthe depth of a refuse bed on a jig screen, which means is extremely sensitive in operation, yet is very rugged and which includes a “?sh”-shaped ?oat mechanism which is en tirely submerged in the jig bed during operation. Other objects of the invention will appear here inafter, the novel features and combinations be ing set forth in the appended claims. Referring to the accompanying drawings: Fig. 1 is a side elevational view of a jig com 25 prising my invention, with parts shown in sec“ tion; ‘ - , Fig. 2 is a front end elevational view of the device of Fig. 1, with parts removed to illustrate certain operating details more clearly; 30 Fig. 3 is an enlarged plan view of the ?oat con trolled mechanism of my invention, with parts shown in section; Fig. 4 is an enlarged elevational view of the mechanism of Fig. 3; 35 be treated, such as raw coal as it is received from’ 10 a mine. [This raw coal may or may not have been previously screened to regulate the size range of A more speci?c objectof the invention is to 20 Said jig comprises a frame I built up of longi tudinal and lateral I-beams and upstanding angle members and plates forming a rigid construc tion which supports a tank 2 formed into two compartments 3 and 4. Said compartments 3 5 and. 4 are similar in most respects. At the left of compartment 3, as viewed in Fig. l, the tank 2 is provided with a material receiving chute 5 which is adapted to receive the raw material to . Fig. 5 is an enlarged plan view of the “fish” shaped ?oat comprising my invention; Fig. 6 is an enlarged elevational view of the ?oat of Fig. 5; Fig. 7 is a sectional view on the line ‘l—-'| of 40 Fig. 6; the material to be treated. Adjacent the right hand end of the tank 2, as viewed in Fig. 1, there is provided a discharge chute 6 for discharging the i5 clean coal from the jig. ' . Within each of the compartments 3 and 4, there is provided a perforate screen plate ‘I which is pivoted at its forward end at 8 and supported by adjustable hangers 9 adjacent‘ the rear end 20 thereof. As is seen in Fig. 2 of the drawings, there are two hangers 9 ‘in each compartment, which hangers are positioned adjacent the side walls of the tank 2. These adjustable hangers provide for an adjustable determination of the inclination of 25 the screen plate which is an important factor in controlling the rate of travel of the bed of ma terials thereacross and maintaining said rate of travel uniform whereby there will be no piling up - of material followed by a “land-slide” thereof. 30 In addition, this adjustable screen provides for a uniform depth of refuse bed over the entire screen which provides uniform conditions of jigging throughout the bed and provides for adjustment of the bed whereby all particles of refuse, regard- 35 less of size, will ?ow toward the refuse discharge opening it at the same rate. This adjustable screen cooperates with the hereinafter described ?oat mechanism to makepossible an automatic withdrawal of refuse while maintaining constant 40 Fig. 8 is an enlarged sectional view on the line conditions of jigging. Adjacent the pivotal position 8 of the screen Fig. 9 is an enlarged elevational view of the‘ plate ‘I, there is provided an adjustable plate 9' 8-4 of Fig. 1; operating means for the refuse discharging rotary .35 valve; Fig. 10 is a sectional view on the line llL-lt of Fig. 9; and . able size which leads to a refuse discharge chute 45 ll within which is positioned a rotary refuse dis charge valve IZ which, when rotated, is adapted Referring particularly to Figs. 1 and 2 of the drawings, there is illustrated a two-compartment jig comprising my invention. It is evident, how ever, that the number of compartments may be to discharge accumulated refuse in the chute II into the boot i3 of an elevating mechanism, gen erally indicated at M, which is operative to remove 50 the refuse from said boot l3 and discharge it out side the jig. The elevating mechanisms M for the two compartments 3 and 4 are driven from a increased or decreased without departing from common electric motor I5 through an appropriate Fig. 11 is a sectional view on the line il-ll of Fig. .1. 50 forming a refuse discharge opening ill of ‘adjust 55 the invention. v drive gearing including the coupling shaft I6. 55 2 2,182,880‘ Within the bottom of each of the compartments use bed and the clean coal forming the upper strata. The clean coal, after being subjected to 3 and 4, there is provided a diaphragm I'I, pref erably circular in circumference, which is ?ex . a jigging operation in said compartment 4, will ibly attached to a ?ange forming a stationary bottom of the compartment by means of a ?ex ible ring I8, preferably made of rubber. Means are provided for imparting a reciprocatory mo tion to said diaphragm [1 along an axis which is slightly inclined to the vertical andwhich is ap proximately perpendicular to the plane of the screen plate ‘I. This means comprises a bracket IT’ to the bottom of which is attached a piston l8’ (Fig. 11) carried by a piston rod l9, which piston l8’ ?ts into a cylinder 20 adapted to be 15 supplied with substantially constant air pressure from an air line 2|. Pivoted to said bracket I1’ is a pair of connecting rods 22 which are pivoted to a rocker beam 23, which rocker beam 23 is piv oted to bracket 24 rigidly attached to the inclined 20 frame channels 25. The rocker beam 23 carries a roller 26 adapted to cooperate with a cam 21 mounted upon a shaft 28. The cam 21 has a groove forming both top and bottom tracksl2'la and 21b within which groove the roller 26 is be discharged over the chute 6. The refuse forming abed on the screen ‘I will be discharged into the chute I I through the open ing Ill and then discharged by the valve l2 into the boot l3 of the elevating mechanism l4, by which elevating mechanism l4 it is elevated to a discharge position and discharged from a noz 10 zle 36. As the refuse from the compartments 3 and 4 are discharged from separate nozzles 36, they will be separately received and may be given individual treatment, if desired. In some in stances, it has been found that the refuse from the 15 second compartment 4 may have su?icient heat value to be sold as low grade fuel. The principal feature of my invention lies in the mechanism for controlling the discharge of the refuse which accumulates on the screen 1. 20 Extensive tests have demonstrated that to'obtain the most satisfactory stratification of the mate rials and consequently the most e?icient separa tion of coal and refuse, the bed of refuse which forms on the screen plate 'I' should be of reason 25 , ably constant depth. It is the primary function of the automatic refuse discharge means of my invention to keep this refuse bed at a reasonably constant depth and to make this operation en 30 phragm l'l during each cycle of operation. tirely' automatic. While numerous attempts 30 An electric motor 3| (Figs. 1 and 2) is pro-v have been previously made to produce this de sired result, none has been entirely satisfactory vided for driving the shafts 28 of each of the com partments 3 and 4, said shafts 28 being connected in actual operation, of which I am 'aware. The by a chain-and-sprocket mechanism 32 including above mentioned tests have indicated certain 35 an adjustable chain ten'sionlng idler 33. It is difficulties in known devices which are overcome 35 in the construction of my invention. evident that as the motor 3| is driven the dia It has been discovered that the ?oat of an phragms ll of the compartments 3 and 4 will be reciprocated causin'g pulsating movement of automatic mechanism should be of the totally the ?uid in the tank 2 with respect to the screens submerged type and in my invention a ?oat 3'! adapted to move. The-connecting rods .22 are pivotally connected to a block 29, which block 29 may be slidably adjusted along track 30 on the rocker beam 23. This adjustment of the block 29 provides for adjustment of the stroke of the dia 1. In the preferred arrangement,' the cycle of operation of these two diaphragms is 180 degrees out of phase thereby'making the load more uni form on the motor 3|, though this arrangement is by no means necessary. 45 The function of the cylinder 20 is to balance the load on each side of thediaphragm I'I so that the motor 3| need supply only su?lcient energy to reciprocate said diaphragm. That is, the air pressure‘ in the line 2| is supplied to the of the totally submerged type is provided. The reason the ?oat should be of the totally submerged type lies in the fact that due to the upward and downward movement of the water in the com ,partments 3 and 4 the ?oat has a tendency to rise and fall ,in said compartments. Unless the ?oat is of the totally submerged type, this rising and falling thereof causes a variation in the separation of the particles of material, whereby‘ amount of water displaced by said ?oat from one instant of time to the next during a complete cycle of operation. This means that in effect the weight of the ?oat is constantly varying from instant to instant during a cycle of operation. Where the ?oat is totaly submerged, this varia tion is avoided. It has also been discovered that for the totally submerged ?oat to be entirely sat 55 isfactory, said ?oat must be so designed that nothing will vary its effective weight. If the sub merged ?oat has a-?at top or even a gradually sloping top, it is found in actual operation that particles of material will rest on the top of the 60 ?oat and thus change its effective weight. This may be caused by the presence of a dead spot directly above the ?oat due to lack of stream the refuse, such as shale, will form a bed directly lining for the upwardly moving ‘water and also 50 cylinder 20 and acts upon a piston within said cylinder 20 to balance the normal load on top of the diaphragm I'I. - An appropriate valve 34 is provided for each of the compartments 3 an 4 to control the admis 55 sion of water to the tanks of said compartments. It will be evident from the above description that when material to be treated-such as raw coal-is fed'to'the jig'over the chute 5, it will be subjected to a jigging operation on the screen plate ‘I by the upward and downward movements of water through said screen plate 'I. This jig ging operation will be so regulated as to effect a due to the inherent tendency for a ?at surface to 65 support any material that may fall thereon. One of the important features of my inven tion therefore lies in the construction of the is, stratification will take place within the com partment 3 with the refuse on the bottom and the\ totally submerged ?oat whereby it has a very sharp back or top. In fact, as is well illustrated 70 coal on theitop. The coal will then be dis charged over the adjustable height weir 35 of in the drawings, the ?oat is substantially “?sh” shaped. ‘m compartment'3 into compartment 4 where an ad 65 onlthe screen plate ‘I while the clean coal and possibly the lighter fractions of refuse, such as bone, will form, in layers above the refuse. That ditional'jigging operation will take place with Referring particularly to Figs. 5, 6 and 7, it is further stratification of the materials with the seen that the ?oat has a fairly bunt nose 38 and ‘lighter particles of refuse now forming the ref an extremely stream-lined tail‘portion 39. The 75 '3 2,182,880 bottom 49 of the ?oat is rather ?at or smoothly . rounded, as best illustrated in Fig. '1. The top or back 41 of the ?oat forms a relatively sharp angle and presents smooth surfaces 42 and 43 which make a relatively sharp acute angle with the vertical. A rib 44 is provided at the center line of the back 41, as best seen in Fig. 5. This particular construction of the ?oat has been found to be very satisfactory: for 10 it effectively prevents any accumulation of ma terial thereon which might tend to vary the effective weight thereof. Furthermore, as the ?oat rises through the bed of material due to the action of the upwardly moving water on the bottom thereof, the top or back thereof will cut through the bed and water will ?ow past the sharply inclined surfaces 42and 43 and prevent any particles from resting thereon. As the water flows downwardly past the ?oat, it will 20 scour the surfaces 42 and 43 and prevent the accumulation of any particles of material thereon. ' D As illustrated in Figs. 5, 6 and 7, the ?oat 31 is preferably of hollow construction and in prac 25 tice may be made of cast aluminum. Core holes 45 are provided for removing the core sand after the ?oat is cast. These core holes 45 will, of course, be sealed, as .by an aluminum plug. The ?oat 31 is also provided with an integral extension adjusted as thus the gravity of separation of coal and refuse may be adjustably determined. The arms 48 of the parallel motion mechanism are keyed to a shaft 63 and are mounted in a. bracket 64 by anti-friction roller bearings 65. The bracket 64 is carried on a cross-beam 66 which extends between the side walls of the tank 2. Mounted on said beam 66 and adjacent one end thereof is another bracket 61 which supports one end of the shaft 63 by a non-friction roller bear 10 ing 68. The lower arms 51 of the parallel motion mechanism are keyed to a small stub‘ shaft which a is mounted on the bracket 64 by roller bearings in a manner similar to that by which arms 48 are mounted on said bracket. It‘ is thus evident 15 that the friction of the parallel motion mecha nism is reduced to a minimum. In addition, the weight of the moving parts of said mechanism, is reduced to a minimum by employing light weight materials, such as aluminum. This results 20 in a very sensitive mechanism which has been found necessary to provide a satisfactory auto matic refuse discharge control device. Keyed to the shaft 63 is an operating lever 69 which is provided with a plurality of holes to receive selectively a couple link 19 which is attached to a downwardly extending rod 11, which rod 11 carries at its lower end an adjustable con As is illustrated in Figs. 3 and 8 of the draw ings, the post 41 is preferably of hollow construc necting link 12 provided with anelongated aper ture 13, as best illustrated in Fig. 9 of the draw 30 ings. The position of the ?oat 31 is effective to control the position of a shield 14 which, inturn, is effective to determine the rate of rotation of tion and may Well be formed of aluminum to re the refuse discharge valve 12. duce its weight. This hollow construction pro-' Before describing in detail the construction 35 of the valve operating mechanism, attention is directed to Fig. 1 of the drawings for con sideration of the general mode, of operation 30 46 provided with appropriate bolt holes and is adapted to receive a connecting post 41. vides for a. minimum of weight with a maximum of strength. As is seen from Figs. 3 and 8 of the drawings, the post 41 is also stream-lined to . reduce its disturbing effect in the bed of ma 40 terials. As best seen in Figs. 3 and 4 of the drawings, the float 31 is connected to a parallel motion mechanism so that the position of the ?oat 31 may control the operation of ‘the valve 12. In .order that the ?oat 31 may be extremely sensi~ tive, the parallel motion mechanism is made ‘as light as possible and the moving parts are mounted upon anti-friction bearings, such as needle bearings. Said linkage mechanism comprises a‘ pair of upper spaced arms 48 between which ex tends a shaft 49 which. is mounted in sockets 59 of said. arms 48 by anti-friction roller bearings 51. (Fig. 3.) The shaft 49 extends through a block 52 which is connected to a lower block 53 by a shaft 54. The blocks 52 and 53 and the shaft 54 ,are positioned within the post 41. Also loosely mounted on the shaft 49 is a pair of spacers 55 adapted to clamp the outside of said post 41} Clamping nuts 56 are provided which. 60 may effect a clamping of the post 41 with respect to said shaft 49. This construction is also dupli . thereof. ' Associated with the shaft 28 is a crank 15 which is effective to reciprocate the rod 16 con tinuously while the jig is operating. This rod 16 imparts a continuous reciprocatory move ment to the bell crank 11. The bell crank 11 carries a pawl 18, or a plurality of said pawls 45 with tips spaced 2. fraction of a tooth apart, adapted to cooperate with a ratchet wheel 19 to rotate said wheel periodically. The shield 14 is effective to determine the number of notches on the ratchet wheel 19 which will be engaged 60 by the pawl or pawls 13 during each reciproca tion thereof. As was above described, the posi tion of the shield 14 will be determined by the average position. of the ?oat 31. The elongated .slot 13 is provided so that the reciprocatory so movement of the float 31 in response to pulsa tions of the water will not be transmitted to said shield 14 but said shield will assume a posi tion determined by the average or mean posi~ tion of said ?oat 31. ~ ' cated with respect to the lower arms 51 of the refuse discharge mechanism should be so ad parallel motion mechanism. The post 41 is provided with elongated aper-_ tures 58 whereby the position of the, ?oat may be justed that in normal operation the pawl 18, or ' adjusted with respect to the parallel motion mechanism. Adjacent its top, the post 41 carries a pointer.59 which cooperates with the station ary scale 60 for indicating the position of the ?oat 31. An upstanding pin 61 isalso provided adja cent the top of the post 41 for receiving a variable number of washers or weights 62 for adjusting the balance of the mechanism. It is evident that by increasing or reducing the number of washers 62, the effective weight of the ?oat 31 may be no It has been found from experience that the one of said pawls if two are employed, will ratchet over at least one tooth of the ratchet 65 wheel 19 during each reciprocation of the belly crank 11, whereby there will be a substantially continuous withdrawal of refuse from the bed formed on the screen 1. If the refuse tends to become’deeper than the pre-determined amount., 7,0 the shield will be withdrawn to allow pawl 18 to ratchet over more teeth of the rachet wheel 19, for each oscillatory movement of the bell crank lever 11. By this mode of operation, va riations in the depth of the refuse bed are small 76 4 2,182,880 and thus constant conditions of jigging are pre sented. As was above set forth, the shield ‘I4 is so adjusted and is so balanced that it will remain at any angular position to which it is moved. This is provided by balancing the mech anism which moves with said shield ‘I4 so that in any angular position of adjustment it will be in static balance. The details of the mechanism for rotating the 10 valve I2 are best seen in Figs. 9 and 10 of the drawings. The discharge valve I2 is of the pad dle wheel type and is mounted upon a shaft 88, which shaft 88 is carried at its outer end by a bifurcated bracket 8|. Said bracket 8I is pro 15 vided with inner and outer bearing sleeves 82 and 83, respectively. The ratchet wheel 19 is keyed to the shaft 88. The shield ‘I4 is carried on arms 84 which arms are journaled on the inner portions of the bearing sleeves 82 and 20 83. The arms 84 also carry a bifurcated bracket 85 which carries a pin 86 which projects into the elongated aperture ‘I3 of the coupling link ‘I2. Arms 84 also carry counter-weights 81 which are eifective to produce the above mentioned 25 static balance of those parts which are rigid with the shield ‘I4 for any angular position of adjust ment of said shield ‘I4. It is thus evident that shield 14 will remain in any position of adjust ment to which it is moved by the ?oat 31. 30 Bell crank lever 11 comprises two armsg‘I‘Ia and ‘I‘Ib, which arms are journaled to the outer por tions of the bearing sleeves 82 and 83, respec tively. It is evident that as said bell crank lever 11 is journaled to the stationary bearing sleeves 35 82 and 83, rotation of the shaft 88 and of the valve I2 will beaffected only to the extent that shield ‘I4 provides for engagement of the pawl ‘I8 with the ratchet wheel ‘I8. Arms I‘Ia and "D are sufficiently spaced from the arms 84 on the 40 bearing sleeves 82 and 83 so as to transmit no reciprocatory motion to said shield ‘I4. If de sired, spacing washers may be placed between the arms ‘I‘Ia and 11b and the arms 84, which wash ers may be keyed to the bearing sleeves 82 and 45 83 to provide a positive isolation of said bell crank lever 11 and the arms 84. It has been found in practice, however, that these spacers are usually not necessary. To provide for a ready removal of the valve 50 I2 through the side of the tank 2 a removable plate 88 (fig. 10) is provided which cooperates with the ring 89 welded to the side of said tank 2. The internal diameter of the ring 89 is greater than the external diameter of the paddle 55 wheel valve I2. An appropriate packing gland 98 is provided to perform a water-tight connec-' _ tion between the plate 88 and the shaft 88. Referring to Fig. l of the drawings, it may be noted that the chute I I, which leads to the valve I2, is provided with a pivoted top plate 9| and an arcuate seal plate 92 adapted to be held in frictional engagement with the valve I2 by a weight 93. This provides a release means for the valve I2 whereby if a large particle of refuse 65 passes thereinto there will be no damage to said valve I2, yet in normal operation there will be sonable limits, and as illustrative it may be known to be from 5 to 10 per cent. With ma terial of the size range being treated, it is known that the approximate refuse bed depth which is desired. For example,‘ with a size range of %"-6 mesh, an average refuse bed depth of 6 inches may be desired. The post 41 is there fore adjusted so that arms 48 and 5'! will be horizontal with the refuse bed 6 inches deep.’ The coupling link ‘I8 (Fig. 4) is so adjusted with respect to the lever 69 that the range of speeds at which shaft 88 may be rotated is sumcient to take care of the range of variations in refuse accumulation normally encountered, with a max imum movement of the lever arms 48 and 51 of 15 15 degrees both above and below the horizontal, making '30 degrees total variation. If the refuse variations are relatively low, then the effective length of arm 69 may be made relatively short whereby the maximum variation in the angular 20 movement of shaft 88 for each reciprocation of bell crank 11 will be from zero, when the ?oat is below normal and arms 48, 51 are 15 degrees below the horizontal, to the angle subtended by two teeth of ratchet wheel ‘I8, when the ?oat is 25 above normal and arms 48, '51 are 15.» degrees above normal. Under the latter’ condition, the rate of discharge of valve I2 will be approximately twice the normal rate of accumulation of the refuse. When the refuse bed is at a normal depth, 30 the average position of the arms 48, 51 will be substantially horizontal under which conditions shaft 88 will rotate through the angle subtended by one tooth of ratchet wheel ‘I9 during each oscillation of the bell crank 'I‘I‘and this rate of oscillation will be adjusted to remove the refuse at substantially the same rate it accumulates, in normal operation. If the refuse begins to ac cumulate at a rate faster than it is withdrawn, then ?oat 31 will rise and shaft 88 will be rotated 40 through the angle subtended by two ratchet teeth during each oscillation of the bell crank 11 whereby refuse is discharged at twice the nor mal rate until a normal bed depth is again estab lished. Should the bed depth fall below normal, 45 which is improbable under the above mentioned adjustment, the shaft 88 will not rotate at all until a normal bed depth is established. It is evident, of course, that the ?oat 31 con tinuously oscillates with the pulsations of the _5Q_ bed under the in?uence of diaphragm II, but as aforesaid, shield ‘I4 assumes a position deter mined by the average position of said ?oat 31 and controls the angular rotation of shaft 88 for each reciprocation of bell-crank 11. 65 Should it be found that there is a wide varia tion in the refu .e content of the material, then the link ‘I8 may be connected to lever 69 to increase the effective length of said lever 68, whereby the angle through which shaft 88 is 60 rotated for each reciprocation of bell crank 11 is that subtended by teeth of ratchet‘ wheel ‘I9 which may vary in number from 0 to 3, or 0 to 4, for a total average angular movement of the arms 48, 51 of 38 degrees. The ranges above men 65 tioned may be increased, if desired. In addition, a‘su?iciently close ?t between the valve I2 and the rod ‘II may be effectively shortened or length~ the chute II to prevent any material, even 'if ened whereby the minimum anguiar'rotation of very fine, from passing into the boot I3 less shaft 88 will be that determined by the angles sub it is discharged by rotation of the valve I2. . tended by 1 or 2 teeth. For example, the range 70 A typical illustration of the mode of adjusting may be from 1 to 3 or 2 to 5 teeth. This is useful when the percentage of refuse is large, or the the device of my invention is as follows: The capacity of the jig is, of course, known bell crank 11 is reciprocated slowly, so that even and raw coal is fed thereto at this capacity. The with a minimum amount of refuse shaft 88 may 75 percentage [of refuse will be known within'rea- . rotate during each reciprocation of bell crank 11 75. 5 2,132,880 through an angle subtended by one or more teeth of the ratchet wheel 19 without removing refuse faster than it accumulates. When two pawls 18 are used half a tooth movement of the ratchet wheel 18 is possible and this may be employed to obtain a greater range of operation of the refuse ejector. For example, the range may then be from 0 to 21/2 or from 1/2 to 3 teeth. These ranges are, of course, merely illustrative and obviously may be expanded or contracted, as desired. In addition to the mentioned adjustment, which essentially affects the position and range of movement of shield 14 and the rate of oscil 15 lation of the bell crank 11, it is necessary to adjust the screen ‘I, as previously mentioned, to obtain uniformity in the depth of the refuse bed over the entire area of the’ screen, as well as uniformity of the'constituents thereof 20 uniformity in the rate of movement of said over said screen ‘I. Said screen 1 should be justed so that the refuse will not tend to and bed ad pile up and then create a “land-slide” but will move continuously and uniformly. When proper ad justment of the mechanism is made, as aforesaid, the withdrawal of refuse is completely automatic. The gravity of separation of the material may be adjusted by adding or subtracting washers 62. An increase in the number of said washers results 30 in an increased gravity of separation. It is evident that the mechanism of my in vention for controlling the discharge of refuse is a very sensitive mechanism, yet it is relatively rugged and free from parts which may get out of adjustment. This extremely sensitive mech anism has been found to be very effective to maintain a relatively constant depth of refuse bed which is necessary for consistent jigging con ditions and an ultimate clean separation of coal and refuse. Every effort is made _to reduce the mass of the moving parts which move in unison with the ?oat 3‘! and to reduce any frictional surfaces which might tend to reduce the sensi tivity thereof. In addition, as has‘ been above 45 pointed out, the particular shape of the ?oat 31 is a very important feature of my invention. In the operation of the jig, raw coal will be fed to the chute 5 and fall through the jigging liquid to the screen ‘I, forming a bed of mate rial. The cyclic ‘upward and downward move 50 ment of the jigging liquid through the screen 1 will stratify the bed of material with the high gravity refuse on the bottom and the coal on top. During this stratifying action the bed will be cyclically expanded and contracted to perfect the stratification. The ?oat 31 will act much like a large particle of material and, particular ly as it is totally submerged, will be Strati?ed in the bed according to its size and weight. These qualities are so determined that said ?oat 31 will be Strati?ed on top of the refuse bed, and within and at the bottom of the‘ bed of coal. The ?oat 31 thus does not truly ?oat on the liquid surface ‘ but is actually stratified on top of the refuse bed. 65 As a consequence the ?oat 31, acts as a very accurate device to determine the depth of the refuse bed and to control the described refuse ejector mechanism to maintain the refuse bed of‘ substantially constant depth, thus insuring too shallow the ?oat comes to rest at a lower po sition and decreases the rate of operation of said discharge valve 12. - _ > . - After the highest gravity refuse is removed from the ?rst compartment 3 the material passes over weir 35 into the second compartment 4' where the intermediate gravity refuse is removed in a manner similar to that above described. The float.mechanism is adjusted, by means of washers 62, to reduce the effective weight of the ?oat 31 in said compartment 4 over what it' was in compartment 3 so the ?oat 31 will properly stratify on top of the intermediate gravity refuse. The clean coal passes from compartment 4 over the chute 6 to be treated as a ?nal clean coal product. While in the description given the apparatus was described as particularly useful for clean ing coal, for which it is primarily designed, it may also ?nd other useful fields of application. 20 Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as de?ned by the claims hereto appended, and I wish therefore not to be restricted to the precise construction herein disclosed. Having thus described and shown an embodi ment of my invention, what I desire to secure by Letters Patent of the United States is: 38 1. In a separator, the combination with. a ma terial support, of means for controlling the depth of refuse on said support comprising, a rotary refuse discharge valve, a ratchet wheel adapted to operate said valve, a pawl for operating said , wheel, means for reciprocating said pawl, a shield for determining the extent of movement of said ratchet wheel during each reciprocation of said pawl, means for adjusting the position of said shield comprising a totally submerged elongated . ?oat having a pointed back whereby material will not tend to accumulate thereon and having a relatively ?at rounded bottom to rest on said refuse bed, and mechanism for connecting said ?oat and said shield including non-friction mountings, whereby said ?oat will control said shield. 2. In a jig, the combination with a screen, of means for maintaining a uniform depth of refuse on said screen comprising, a rotary discharge valve, a ratchet wheel for rotating said valve, a lever, means for'reciprocating said lever, a pawl carried by said lever adapted to engage said ratchet wheel, a shield adapted to determine the extent of rotation of said ratchet wheel for each reciprocationof said lever, a totally submerged ?oat having a sharp top and adapted to indicate the depth of refuse on said screen, linkage mech anism connecting said ?oat and shield including a’ lost motion connection whereby said shield assumes a position determined by the‘ average positionof said ?oat, and means to balance said , shield whereby it will remain in any adjusted position. 1 3. In a separator, the combination with a ma terial support, of means for stratifying material on said support to form a bed of refuse, means for discharging refuse including a rotary valve, a ratchet wheel for rotating said valve, a lever, means for reciprocating said lever, a pawl car ried by said lever adapted to ‘engage said ratchet substantially uniform conditions of treatment for the raw coal with resulting uniform results. That-is, if the refuse bed tends to become too . Wheel, a shield constructed and arranged to de deep the ?oat comes to rest at a higher position termine the extent of rotation of said ratchet wheel for each reciprocation of said lever, a to and'increases the rate of operation of the dis tally submerged ?oat having a sharp top and charge valve I2, and if the refuse bed becomes 75 6 2, 132,380 constructed and arranged to position itself in accordance with the depth of said refuse bed, and linkage mechanism connecting said ?oat and shield including a 10st motion connection whereby said shield assumes a position deter mined by the average position of said ?oat. 4. In a separator, the combination with a. ma terial support, of means for controlling the depth of refuse on said support comprising, a discharge 10 valve of the rotary type, pawl and ratchet means for rotating said valve, a shield cooperating with said pawl and ratchet means to determine the extent of movement of said valve, means for ad justing the position of said shield comprising an elongated totally submerged ?oat having a pointed back whereby material will not tend to 5 accumulate thereon and having a relatively ?at rounded bottom substantially devoid of comers adapted to rest on said refuse bed, and mech anism for connecting said ?oat and shield where by said ?oat will control said shield. JOHN G. A'I'I'WOOD.