US2742153A

US2742153A - Wash box discharge control

Info

Publication number: US2742153A
Application number: US312982A
Authority: US
Inventors: Charles W Lotz; Clarence M Kazmier
Original assignee: Link Belt Co
Current assignee: Link Belt Co
Priority date: 1952-10-03
Filing date: 1952-10-03
Publication date: 1956-04-17
Anticipated expiration: 1973-04-17

Description

April 17, 1956 c, w, LOTZ ETAL (2,742,153

- WASH BOX DISCHARGE CONTROL 7 4 Sheets-Sheet 1 Filed Oct. 5. 1952 INVENTORS Charles W Lotz Q CMrmae 111. Kazmier 1y ;ORNEY April 17, 1956 c. w. LOTZ EI'AL WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 2 Filed Oct. 5. 1952 v 1 m 4 m H I v n M 1 J 2:: a a IUVUI z fl 9 9 lnz gzliw 0 Mn 02 lul- $12 Charles 715L051 Qzd April 17, 1956 c. w. LQTZ arm. 2,742,153

WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 5 Filed Oct. 3, 1952 \SUPPLY AIR INVENTORS Charles W L052 Qd ClarmwMKazmier April 17,1956

Filed Oct. :5, 1952 c. w. LOTZ ETAL 2,742,153

WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 4 IN VENTORS Cizwrhs MC L022 Q61 ClarazceMKwzmier QQZ United States Patent WASH BOX DISCHARGE CONTROL Charles W. Lotz and Clarence M. Kazmier, Chicago, Ill.,

assignors to Link-Belt Company, a corporation of Illinois Application October 3, 1952, Serial No. 312,982

18 Claims. (11. 209--496) This invention relates to new and useful improvements in wash box discharge controls and deals more particularly with an automatic discharge control adapted to vary, through a rangeof values, the rate of discharge of the high gravity stratum from a wash box which is designed for handling coal or other minerals.

Due to the wide variation in the ratio of high to low gravity particles occurring in the minerals normally processed in a wash box, the rate of accumulation of the high gravity particles in the bottom of the wash box'will also vary considerably over a given period of time. It is conventional practice, therefore, to intermittently discharge the high gravity particles in accordance withthe depth of the bed or stratum of such particles in the Wash box.

One form of automatic control of the discharge of the high gravity particles has, in the past, provided on and V oii' operation with, in some instances, two rates of discharge in the on position. Since the rate of accumulation of the high gravity particles in the bottom of the wash box seldom equals the rate of discharge afforded by this type of control, changes from the off to the on position or between the two speeds in the on position were frequent and caused the operating characteristics to be somewhat irregular. For example, if the rate of accumulation fell just below the rate of discharge at the higher of the two speeds, the stratum of high gravity particles would increase in depth until the control device actuated the high speed discharge. The depth of the stratum would then drop and the speed of discharge would be reduced to its lower value whereupon the depth of the stratum would again increase. With each of these changes, the pressure required to pulsate the hutch water in the wash box and the stratifying action of the hutch water would be varied. v

A common prior art type of control has been dependent upon the use of a float having'such a specific gravity that r i it responded to changes in the depth of the stratum of high gravity particles and thus regulated the discharge of the such particles in accordance with the response. The use of such a float type control necessarilyinvolves 2,142,153 Patented Apr. 17, 1956 r6 ICC tions due to changes in the. total depth of the high and low gravity strata and the size consist. I p

Other objects and advantages of the. invention will be apparent during the course of the following description;

.In the accompanying drawings forming a part of this specification and in which like reference characters are employed to designate like partsthroughout the same,

Figure 1 is a fragmentary elevational view, partly broken away, of the discharge end portion ofa wash box embodying this invention, i I

Figure 2 is a vertical sectional view of the discharge chute andgate illustrated inFig. 1, I

Figure 3 is an elevational view, partly in cross-section, of the step-by-step drive for the discharge gate and the mechanism for adjusting the drive,

Figure 4 is a fragmentary elevational view,; partly broken away, showing the connection between ;the drive adjusting mechanism and its actuation controller,

Figure 5 is a. detail elevational view of the discharge gate drive illustrated in Fig. 3, 1 v

Figure 6 is a fragmentary sectional view ofthe actuation controller for the drive adjusting mechanism,

Figure 7 is a perspectiveview showing the arrangement of and connections betweenthe control elements within the control housing illustratedin Fig. 1, t

Figure 8 is a detail side elevational view of the switch operating cam and follower illustrated in Fig. 1,

Figure 9 is a partly 'elevational view. and 'partlyzsectional view of theswitch and cam illustrated in Fig. 8,

Figure 10 is a schematic view of two of the"control elements illustrated in- Fig. 7, and

Figure 11 is a schematic view ofthe differential pres sure relay and the fiowindicator and reducing valve of Fig. 1. t

is shown a preferred embodiment of this invention," and first fparticularly referring to Fig. 1, there is shown a commercial form of washing jig that includes a wash box 11 which has its upper portion divided into front and rear sections by the longitudinally extending partition 12. These two sectionsof'thewash' box 11 are inop'en communication beneath the lower edge of the partitiorilZ which lies in spacedrelation to the bottom of the wash box. 'A pressure tight cover 13 closes the top of the rear longitudinal section. t

The front longitudinal section of the wash boxll is provided with a material bed supporting screen 14 having a downwardly inclined end portion 15 which acts as i a discharge chute. The lower end portion of the dissubjecting the fioat to abrasion and corrosion and, there- I fore, requires a substantial amount of maintenancefor proper functioning. Further; when itv is. desired to change the depth or consistency of the high gravity stratum, mechanical adjustment of the control system, or changes in the weight of the. float assembly, are involved.

It is the primary object of this inventionto provide a control device for use in connection with wash boxes to automatically regulate the rate at which the high gravity particles are continuously discharged therefrom, in 'response to changes in the pressure required to;force the wash water through the stratum of such particles, so as to maintain at a substantially constant depth the stratum of such particles in the wash box. 7

A further object of the invention is to provide a wash rate at which the high gravity particles are continuously charge chute 15 isenlarged and so-formed as to receive a rotary discharge gate .16 mounted on and carried by the shaft 17, as illustrated in Fig. 2. A slide gate 18 acts to regulate the effective depth of the discharge chute 15 and is carried by a rod '19 having its upperend portion in the form of a rack 21 for "engagement with the pinion 22 keyed to the shaft 23 which may be rotatedto rais'e'or lower the slide gate 18. 1

The end wall of the wash boxll above the discharge chute 15-is provided with an exit sluice 24. "An inlet sluice, not shown, similar to t'he exit sluice 24 may be utilized to introduce material to the opposite end portionofthewashboxll. i When the illustrated washing jig is in operation, the wash box 11 is provided with water up to the desired level. The pressure tight rea-r longitudinal section is corinected to a compressed air receiver 25 through the. air inlet pipes 26 which are provided with valves 27 that In the drawings, wherein for the purpose of illustration,

are operated "simultaneously by the earns 28, rotated by the camshaft 29, to impart reciprocating motion to the valve operating rods 31, as illustrated in Figs. 8 and 9.

When the valve operating rods 31 are in their lower positions, the valves'27 permit compressed air to flow from the receiver 25 through the air inlet pipes 26 into the longitudinal section at the rear of the wash box 11. This compressed air'forces the water in the rear section to pass under the lower edge of the partition 12 to force the water in the front section "to rise through the material bed supporting screen'14'and the material bed B. When the valve operating rods 31are in their upper two end positions of oscillation of the radial arms 38 and pawl 39 are illustrated by broken lines in Fig. 3 and the pawl 39 is lifted out of engagement with the ratchet wheel 42 during a major portion of its oscillating movement. Rotation of the cam discs 43 to relocate their stepped portions 44, therefore, acts to determine that portion of the path of travel of the radial arms 38 through which the pawl 39 engages the ratchet teeth.

' Each cam disc 43 is provided with an extension arm positions, the valves 27 act to close the air inlet pipes 26 and exhaust the compressed air from the rear longitudinal'section. The water in the front sectionof the wash box will, therefore,s'eek the level of the water in the rear section whereby the water in the front section passesdownwardly through the material bed B and its supporting screen 14.

A starting mixture of mineral particles of different specific gravities and wash water-is sluiced, or otherwise introduced, into the feed end of the front section of the wash box 11. The mineral particles will be advanced lengthwise of the front section by the longitudinal hydraulic flow through the wash box 11. While advancing toward the exit end of thewash box 11, the mineral particles of different specific gravities are'stratified by the pulsations of the water so that the higher gravity particles are concentrated at the bottom of the material bed B and can be withdrawn through the discharge gate 16. The lower gravity particles will collect along the upper stratum of the material bed B and will spill into the exit sluice 24 with a'certain amount of water during each pulsion stroke.

' The above structuralfeatures of the washing jig are conventional and are more completely illustrated and described in the copending Charles W. Lotz application,

Serial No. 148,213, filed March 7, 1950, now Patent No.

2,609,098, for Method of and Apparatus for Continuously Cleaning and Separating Minerals of Different Specific Gravities, which application is a continuation-inpart of application, Serial No. 753,524, filed June 9, 1947 and now abandoned, and bearing the same title.

The discharge gate 16 and its drive mechanism are of the type illustrated and described in the patent to E. J. Burnell et al.,-No. 2,106,204, dated January 25, 1938, ,and will be only briefly described as follows:

The motor 32, having a starting switch 33, is connected by a belt 34 to a speed reducer 35. It is to be understoodthat a direct'coupling or other suitable device I may beused to 'drivingly connect the motor 32 to the speed reducer 35.. The speed reducer 35 is provided with a crank arm .36 having a connecting rod 37 pivoted to its outer end portion. As is illustrated in Figs. .1, 3 and 5, the other end portion of the connecting rod 37 is pivotally connected to a radial arm 38 which is free to pivot about the shaft 17. The length of the radial arm 38 is greater ,than the length of .the crank arm 36 so that rotation of the crank 'arm acts through the connecting rod- 37 to impart oscillatory motion to the radial arm 38. The radial arm 38 carries .a pawl 39 which is depressed by the spring 41 for engagement with the teeth of a ratchet wheel 42 which is keyed to the shaft 17'. The oscillating motionof the radial arm 38, therefore, imparts an intermittent rotation to the discharge gate 16 which is carried by the shaft 17.

Control of the effective length of intermittent rotary motion of the discharge gate 16, as illustrated in Figs. 3 and 5, is provided in the following manner: A pair of cam discs 43 are rotatably mounted on the shaft 17 adjacent opposite sides of the ratchet wheel 42 and are each provided with a similarly located stepped portion 44 for engaging a roller 45 on the pawl 39 to liftthe pawl from engagement with the ratchet during a 46, and a pin 47 connects the two extension arms to one end portion of an operating rod 48. Movement of o the operating rod 48, therefore, will simultaneously rotate both of the cam discs 43 to effect the desired relocation of their stepped portions 44 so that the pawl 39 will impart the desired amount of intermittent rotary motion to the discharge gate 16. In addition to the arms 46 and pin 47 the cam discs 43 are rigidly connected to each other by oppositely arranged pairs of arms '49 and 51, and pins 52 and 53, respectively, which connect the arms of each pair.

The starting switch 33 of the motor 32 is connected to a source of supply of electric energy through the lead wires C, D and E and the motor is operated continuously during the periods of operation of the wash box 11. The rate of rotation of the discharge gate 16 in the chute 15, however, is controlled by an automatic control system which is responsive to the depth of the stratum of heavier particles that accumulates adjacent the material bed supporting screen 14. In other words, when the stratum of heavier particles increases in depth the discharge gate is operated at a faster rate to increase the discharge of heavier particles through the chute 15. When the depth of the stratum of heavier particles decreases, the cam discs 43 are adjusted to decrease the rate of discharge by the gate 16 with the final result that the thickness of the stratum of heavier particles remains at a substantially constant value.

The present invention provides for the above discussed control of the thickness of the stratum of heavier particles in response to changes in the pressure required to force the wash water through the material bed 3 as the thicknessof the stratum of heavier particles varies. As was previously pointed out, the rate of discharge of the heavier particles is adjusted by movement of the operating rod 48 to vary the position of the cam discs 43 and the desired control of the discharge rate is, therefore, accomplished by properly positioning the operating rod in accordance with the hydrostatic pressure of the wash water in the bottom of the material bed B.

Referring now to Fig. 1 for a brief description of the complete system employed for controlling'the.operation of the discharge gate 16, reference character 57 designates a pipe or tube, connected to a suitable source of compressed air, not shown, for supplying air to the control system at a pressure of between 30 and lbs. per square inch. The compressed air flowing through the tube 57 successively "passes through a trap 58, which removes water, oil and dirt from the air, and a pressure reducing valve 59 from which the air flows at a reduced constant pressure of, for example, 20 lbs. per square inch. The air from the pressure reducing valve 59 passes into a suitable coupling 61 where it is divided for How into three separate branches of the control system.

One of these branches leading from the coupling 61 passes through, a constant differential pressure relay 62, a flow indicating device 63 and a throttle valve 64 which is combined with the flow indicating device. As illustrated in Fig. 11, the differential pressure relay 62 includes a valve 65, or similar flow restricting device, which is operated by a diaphragm 66 one side of which is exposed to theconstant pressure of 20 lbs. per square inch of the air entering the relay. The other side of the diaphragm 66 is in open communication through the tube 67 with the low pressure side of the throttle valve 64. The-valve 64 reduces the pressure of the air flowing through the indiwash box 11;

email-a *5 eating device: 632 to a value: offapproxiinately' 3 lbs. per square inch but; as. will: betlater described;, the pressure orrthe'l'ow sid'ev'of the throttle valve. 64 will vanyr through a' relatively small range during: each pulsion of the water in the-'washbox-ll and will alsovary:in:.accordance'with the;depth.=.of the: stratum oft high gravity; particles: in the In orderto maintain-the: rate of. flow ofiair' through the throttlevalve: 64 ata. constant value despite fluctuations. in the pressure; on: the low side of. the valve, the pressure drop: across the: valve 64-must bemaintai'ned': at a: constant value; This is; accomplished by subj'ecting one side ofv the diaphragm: 66nto; the varying pressures on the low side ofithe: valve 64.? while the pressure on: the opposite side. of: the: diaphragm is. maintained at a constant valueof 20 lbs. per square inch. The varying pressure to:which.the one side-of the diaphragm 66 is exposed will. cause the valve 65-.to be'opened or closed a sufiici'ent amount: to maintain the pressure of: the air enteringthe-throttle valve 64xat the-desired value above that of the air on the low pressure side of: thiselatter' vallve. In

this manner, the rate at which the: compressed air flows from the valve 64 into thetube 68' is maintained at a constant' value despite limited variations inJthe pressure ofv the air in the tube.

- Referring once again to Fig. 1,.theairfrorn the valve 64 fiowsthrough the tube 68 to a. pipe 69 which: extends downwardly through the material bed Bin the wash box 11 to the supporting screen 14; The level. of. the water in the wash box 11 will, of course',.varyi with each pulsathe" tube 72 passes through 'amanually operated valve 75and into the encased portion ofthe control. system which is designated in its entiretyiby the reference character 76 and which will be morefully' desribed'at alater Point.

Neglecting the insignificant amount of friction between the pipe 69'and the air flowing therethrough, the pressure of the air in the'pipe may be assumed to be equal "to "the pressure exerted by the water resisting the discharge of the'air from the opening171; This hydrostatic pressure will, of course,.vary during each pulsion stroke of-the water but, at a given point during each-such stroke, the pressure will vary primarily in accordancewith thethickness, and, therefore, the-hydraulic resistance, ofthe material bed B to the flow of the water therethrough. In order to prevent large fluctuations of pressure in the tube 72 during successive pulsion strokes'of the water, the actuation of the solenoid valve 73' is timed to provide comrnunication between the tube 72' and the pipe 69 only duringthe same small portion of each-'pulsionstroke. The pressure in the tube 72, therefore, is relatively constant, and will vary only in accordance with changesin the'pressure of the water at the opening 71 which result from changes in the hydraulic resistance of the-stratumof heavier particles in the bottom portion of the material bed-B. q

Intermittent action 'ofthe" valve 73 in the manner described above results from a similarly intermittent actu'ation of the solenoid 74 which is accomplished by a switch 76' mounted on one of the valve operating rods 31, as illustrated in Figs. 1 8 and 9', and a" switch operating, lug 77 arranged to engage the operatinglever 78 of the switch 76for a given portion and ma given point of each revol'ution ofthe cam 28'. Inasmuch asthecam28 controls the operation of thevalve 27 and, therefore; the pulsations of the washwater and the operating lug: 77 controls the act uati'on of the. switch: 76 to open and closevthe valve73,

6 28 will provide for synchronization oi the; operation of the valve 733 with the: pulsations: oi the: wash water;

The-wires F and G-areconnected to a suitable: source of supply of electric energy for operating the valve 73 through the switch 76: and the solenoid 74; One side of the switch 76' is. connected to the wire F and the other side of the switch is connected throughthe solenoid 74 to the wire: G. i

A second. branch of the control system is connected directly to the coupling 61 by the tube 79 which extends to the encased portion 76 of the control system.

A third branch of the controlsystem extends from the coupling 61 through the tube 81 to a pilot valve'housing 82 whichis illustratediin Fig. 6 as being provided with an inlet port 83, an exhaust port. 84 and an output port 85 in additionto a control port 86 through which compressed air is admitted to automatically control the operation of the pilot valve 87. The: automatic operation of the pilot valve 87 willbemore fully'described at a later point but at this time it will benotedthat the position of the pilot valve controls both the amount of air that flows through the inlet port. 83 and the tube 81 and the portion of this air that. is vented to the atmosphere through the exhaust port 84 to thereby control the pressure of the air at the output port 85. In other words, the pressure of the air at the port 8S may be increased, decreased or maintained at a constant value depending upon the position of the pilot valve 87..

. Thetube 83 that is connected to the output port 85 is illustrated in. Fig. 3' as providing communication with the chamber 89 located in the upper portion of the operating rod positioning device 91. One wall of this chamber 89" is formedby a diaphragm 92 which is actuated in accordance with the pressure of the air in the chamber 89. The diaphragm 92 and its backing plate 93 are urged in a direction to oppose the pressure of the air in the chamber 89 by a spring 94 and the upper end portion of therod' 48', whichrotates the cam disc 43, is connected to the backing. plate. Downward movement of the diaphragm 92 caused by the air pressure in the chamber 89 is limited by engagement of the stop 95 on the backing plate 93 and the stop 96 on the supporting frame of the positioning device 91.

It will be: readily apparent, therefore, that as the pressure oftheair in the chamber 89 is increased or decreased or: is maintained at a constant value, within the range of fronrO to 20'lbs. per square inch, the cam disc operating me 48 will. bemoved, respectively, downwardly or up- Wardly or will be maintained in a stationary position.

Downward movement of the rod 48 will cause rotation of thecam discs: 43 in a direction to increase the length of throw of the step-by-step drive for, and the rate of rotation of, the discharge gate 16, while upward moveproper mounting of the switch operatinglug 77 on the earn 7 ment oi the rod will decrease said length of throw and rate of rotation. Maintaining the rod in a stationary position will cause the length of throw and the rate of rotation to be maintained at a corresponding constant value.

The control port 86 of the pilot valve. housing 82, through which compressed air is admitted to control the operation of the pilot valve 87, is illustrated in Fig. 1 as being connected to the encased portion 76 of the control system hya' tube 98.

Referring now to Figs. 7 and 10 for a detail description of the portion of the control system that is housed in the" casing 76, and first particularly referring to Fig. 7, the tube 721 which is in intermittent communication with the pipe69 through the valve 73, during like portions of successive pulsations of the wash Water, is connected to apressure bellows 99 which will expand or contract as thepressure in the tube 72 increases or decreases, respectively. It. will be appreciated that any pressure responsive or pressure measuring gauge capable of producing a; change in position of a signal element may be substituted for the pressure bellows disclosed. The bellows 99 is supported at its lower end by a bracket 101 while connected to the free upper end portion of the bellows is a rod 102 which is movable in accordance with the pressure of the air in the bellows. The upper end portion'of the rod 102 is pivotally connected to one arm of a crank 103 which is pivotally mounted on and supported by a shaft 104. The other arm of the crank 103 is pivotally connected to one end portion of a link 105 which has its other end portion pivotally connected to an arm 106 rigidly mounted on the rotatable pointer shaft 107. Fixed on one end portion of the shaft 107 is an indicating pointer 108 the weight of which is balanced by two counterweights 109. Changes in the pressure of the air within the bellows 99, therefore, will impart rotary movement to the shaft 107 through the above described linkage and will cause movement of the pointer 108 in direct relationship with the changes in the pressure.

A second arm 111 is rigidly connected to the shaft 107 and the outer end portion of this arm is pivotally connected to a measurement link 112 which extends to and is connectedwith a vane positioning arm 113 that is rigidly connected to a rotatable shaft 114 upon which is mounted a vane 115 having a radial end edge 116. The motion of the pointer shaft 107 is transmitted by the .measurement link 112 to the vane positioning arm 113 so that the vane 115. is moved through an arcuate' path as the pressure in the bellows 99 varies.

The tube 79 of the control system is shown in Fig. 7 as being connected to a pressure gauge 117 which indicates any deviation from the desired operating pressure of, for example, 20 lbs. per square inch. From the pressure gauge 1.17, the air flows through a tube 118 to the pilot valve amplifier 119, see Figs. 7 and 10, and, also, through a restricted orifice 121 to the tube 122. The tube 122 is connected to a jet housing 123 which is mounted for pivotal movement concentric with the axis of the shaft 114upon which the vane 115 is rigidly mounted. The jet housing 123 has branch passageways therein in communication with the tube 122 and openingfrom the housing through opposed jets 124 which are arranged in closely spaced relationship on opposite sides of the path of travel of the vane 115.

Compressed air passing through the tube 122 is continuously discharged from the jets 124 and it will be readily apparent that back pressure will develop in the tube 122 which will vary in direct relationship with the portions of the opposed jet openings which are covered by the end edge 116 of the vane 115. Inasmuch as the jet openings are very small, any slight movement of the vane edge relative thereto will effect a very substantial variation in the back pressure of the air flowing through the tube 122. For example, the orifice 121 and the openings in the jets 124 may be so formed that when the vane edge 116 is moved half the distance across the jet openings the back pressure in the tube 122 will be equal to lbs. per square inch. Under these conditions movement of the vane 115 through a distance of .0025 inch in one direction will cause an increase in the back pressure in the tube 122 of /2 lb. per square inch and movement of the vane for a similar distance in the opposite direction will cause a corresponding decrease in the back pressure in the tube 122. This combined variation of 1 lb. per square inch in the back pressure in the tube 122 is sufficient to operate the pilot valve amplifier 119 as will be later described.

The jet housing 123 is moved relative to its shaft 114 by means of a set-point knob 125 which rotates the gear set 126 to actuate the rack and pinion 127, the rack of which is connected to the jet housing 123. The rack also is connected through the link 128 andsarm 129 to a rotatable shaft 131 which is to berotated by movement of the'jet housing 123. Mounted on the shaft 131 and positioned adjacent the pointer 108 is a set-point index 132.

It will be recalled that when the wash box 11 is operating in a satisfactory manner the depth of the stratum of high gravity-particles in the bottom of *the bed of material B is maintained at a constant value by rotation of the discharge gate 16 at a given rate. The hydrostatic pressure of the wash water at the'opening 71 in the pipe 69 will, therefore,remain at a constant low value which is equal to the pressure of the air in the pipe and which iis also equal to the pressure of the air in the bellows 99 during the same portion of successive pulsations of the water. This pressure in thebellows 99 is measured and indicated by the pointer 108 and the set-point knob is rotated to adjust theposition of the set-point index 132 to correspond to that of the pointer 108. When so adjusted, the'ed'ge 116 of the vane 115 is positioned relative to'the openings of the jets 124 so as to cover one half of the'area of the jet openings. The back pressure in the tube 122 will, therefore, be 5 lbs. per square inch. That portion of the air flowing through thetube 79 which passes through the tube 118 to the pilot valve amplifier 119 is admitted to the latter through a supply port 133 and is discharged through an exhaust port 134 in accordance with-the position of the ball 135, see Fig. 10. This ball 135 is moved toward and away from the supply and

exhaust ports

133 and 134 by a pin 136 which is supported by the diaphragm 137. A light spring 138 urges the ball into constant engagement with the'pin 136. As the ball 135 is moved to vary the rates at which the air is admitted to and exhaustedfrom the pilot valveamplifier, the pressure of the air within the amplifier and within the tube 98 is variedin a direct relationship.

In other'words, an increase in the back pressure in the tube.122 is transmitted through the branch tube 139 to the diaphragm 137 where it will cause movement of the pin 136 to reduce the supply of air to the pilot valve amplifier and to increase the rate at which the air is exhausted through the port 134.. The pressure of the air within the tube 98 is thereby reduced in inverse relationship with the back pressure of the air in the tube 122. On the other hand, when the back pressure of the air in the tube 122 is reduced, the pressure of the air on the diaphragm 137 is reduced .and the ball is permitted to move toward the exhaust port 134. and away from the supply port 133 so that the pressure within the pilot valve amplifier is increased to thereby cause an increase in the pressure within the tube 98. The rate of flow of the air through the tube 118 and the size of the supply and

exhaust ports

133 and 134 are 'such that a variation in the back pressure in the tube 122from 4 /2 to 5% lbs. per square inch will cause asvariation of from 15 to 3 lbs. per square inch, respectively, in the pressure of the air within the tube 98. A back pressure of 5 lbs. per'square inch within the tube 122, therefore, will provide a pressure of 9 lbs. per square inch in the tube 98. I

As illustrated in Fig. 6 the tube 98, leading from the pilot valve amplifier 119, is connected to the control port 86 of the pilot control valve 82. The control port 86 is in open communication with the interior of an annular or double walled pressure bellows 141, the upper closure plate of which is movable by an increase or a decrease in the pressure of the air within the bellows. Supported by the closure plate of the bellows 141 and extending toward the exhaust port 84, is a cylindrical collar 142 having amounting spider 143 at its lowest end portion for connection with the operating rod 144 of the pilot valve 87. The operating rod 144 extends inwardly through the exhaust port 84and. provides sufficient clearance therewith to permit the free flow of air from the port through the spider 143 and the collar 142 for release to the atmosphere. A balance spring 145 is compressed between the closure plate of the annular bellows 141 and a collar 146 whichis mounted for vertical movement on the shaft 147 and which is adjustable to vary the vertical distance betweenits top surface 148 and the surface against which the spring 145 abuts.

As illustrated in Fig. 3, the top surface 148 of the collar 146 is engaged by the free end of a pivotally mounted arm": 149 wliicli is forced? in a. direction fon engagementwith-.th'e surfaces 148' bya roller." 151 that is: adjustably. mounted on a second arm.15'2.. One end: of the arm 152' is pivotallysupportediadjacentthe. free end. of thearmi149 andf'its other'endiis pivotally connected. to: the. vertical linkt1'5'3.. As illustrated in Figs; 3 aud t, thevertical link.

1'53 is connected tothe'operatingrrod 48* by a.horizontal link-.154. i a

Referring: now to Figs. 31, 4 and 6, andrecallingzthat thepressureiof the air in the tube 98 will. vary within the range of from 3 to l'S: lbs. pen-square inch and will be: atta pressure of 9 lbs: per square inch whenithe depth ofi'the stratum of. high gravity particlesv in the wash box 1 1' is at itsdesired. value, the-'operation'of. the pilot control valve87t to regulate the. position of the operating rod 48 willibe' describedasifollows:

With the pressure ofthe air in the tube. 98 at a value ofr9- lbs. per. squareinch,the'pressurewithin the bellows 141 will alsobe 9 lbs. per square inch and the-spring 145Will be adjusted by means of the collar 146 to exert an force-on the bellows which= willybalance the force of the? air. withinthe bellows. In this connection it will be notedthatwhen the cam discs-43 and their operating rod 48 are in* the proper position to provide a rate ofrotation for: the gate 16= which. will maintain a proper. depth for thestratum of high gravity particles, the? arm 149wil1 be maintained in a given position by means of the links1'53 and 154'i and the arm 152" and roller. 151. Adjustment ofthe: collar 146; therefore, will be made to. balance the force of the spring 145 against the pressure of the air in the. bellows 141'while the .rod 48 is in this desired positionr.

Atrise or fall of the pressure of: the": air within the. tube 98s will thereafter. move the pilot valveY87 in: the proper directionto increase or decrease, respectively, the pressure o t-the air in the tube 88 andin the diaphragm chamber 89:. As the pressure of tlie air inthe-chamber 89 is increased or decreased, the rod. 48 will be repositioned and the compression of the spring 145* will be varied by the movementsoftthelinks 153 and1154' and the arms 152'and 149 to*rebalance the forces" applied to theoellows 141 by the: spring 145:and by the. pressure" of the air. within the bellows.

The operations of the various portions of the control system .havebeen described above andwill-not be repeated at this time. The operation of thecontrol. system. as a unit, however, will; be briefly; described as follows;

.With the discharge; gate 16 rotating at, a properrateto maintain: the: stratum'of' higlr gravity particles in the bed B ofthe'washbox 1 1 atthe desired: depth, the. hydrostratic pressure at the opening. 71 of the pipe 69' is im: pressed-upon the pressure bellows 99' during like portions of: successive pulsations ofcthe washwater. .This pressure withinrtheibellows 99 istransmitted through the. linkage whichsconnectss the bellows .to the: vane 1'15 and: will. position the vane so that its edge 116 will be midway: across the area. of the opposed: jets:124.' This .position. of the vane 115 will cause the back pressure in the tube 122 to equal: lbs. per" square inch which: is the pressure; at which: the'pilotvalve amplifier 119 is. actuated'to provide an=outputpressure of 9 lbs; persquare. inch. This pres+ sure'insthetube 98 is impressed upontheannular: bellows 1x41; to=balanceatheg pilot valve; 87 in azposition atwhich the; pressure inthe tube 88. and chamber89 of the positioning device: 91,, will: maintain the. operating rod 48 in its. desired position for adjustment of: the cam discsl=43l to provide? theabove: mentioned rate of. rotatiomforf the gate 161. i

'A-ny. deviation in: the: depth. of the'stratum of high gravity particles from its desired value will cause: a change inthe pressure of the airinthe pressure-bellows 9 9 and a change in the position-of the vane- 115' in a direction and by anfamount which are directly, proportionalito the' change of pressure in the bellilws 99. A veryslig lit" movement of tlievane 1'159will eifect" a substantial. change in the back pressure in the: tube 122; and an: even; greater}; change in the: output; pressure of the pilot valve amplifier 119 ,in'the tube 98;. This ampli-. fiedfpressure variation in the tube 98: is impressed upon the bellows 141/to eflect an immediate change in the pressure in the tube 88 and the chamber 89which is controlled by the position of the pilot valve 87. Variations, of thepressure-inrthe chamber 89 willcause movement of. the operatingmod 48 to properly adjust the position of the cam discs 43 to regulate the rate of rotation of the gate 16 andwill rebalance the forces exerted. on the bellows 141 by the spring 145 and by the pressure of the air within. the bellows to recondiwith a ,wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid,

means forproducing apulsating flow of washing liquidv through said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drive means for rotating saidgate at avariable rate to control the rate of discharge of materials, of means for introducing a control fluid directly into and against the variable pressure. of the washliquid at a point at which thepressure of the washing liquid varies proportionately with changes. in the hydraulic resistance of the material. bed, means for amplifying the pressures of the control fluid in said introducing,meansduring. like portions of successive pulsations ofthe washing liquid, and

fluid pressure operated means responsive to. variations inthe amplified pressures for varying the rate at which said gate is rotated to cause the discharge of materials byathe gateto maintain the hydraulic resistance of the bed: substantially constant. 1

2. In; a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing. a pulsating: flow of washing liquid through said bedof materials, a rotary gate for dischargingmaterials from said box, and continuously operating drive means for rotating said gate at a variable rate to control the rate of discharge of materials, of means for introducing a control fluid directly into the washing liquid at apoint near thebottom' of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, meansfor amplifying the pressures of the control fiuid during like portions of successive pulsations. of the washing liquid, and means operated by said amplifiedprcssuresfor varying the rate at which said' gateis. rotated to vary the material discharge rate through a range of values corresponding to thetvariations in said hydrostatic pressures of the washingliquid.

. 3'. In adevice of the type described, the combination with a wash box; having a bed of materials therein adapted to be: acted upon by a body of washing liquid,

means'for producing a pulsating flow of washing liquid through" said bed of materials, arotary' gate for discharging materials from saidbox, and continuously operating drive means for rotating said gate at a variable rate to control the rate of discharge of materials; of a pipe for like portions of successive pulsations of 'the washing liquid, and means operated by said amplified pressures for varying the rate at which said gate is rotated to vary the material discharge rate through a range of values corresponding to said hydrostatic pressures of the washing liquid.

4. In a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquidthrough said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drive means for rotating said gate at a variable rate to control the rate of discharge of materials, of means for introducing a control fluid directly into the washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, pressure amplifying means, means for establishing communication between said introducing means and said amplifying means during like portions of successive pulsations of the washing liquid, pressure fluid operated means for varying the rate at which said gate is rotated by said drive means, and means for applying the pressures from said amplifying means to said pressure fluid operated means to increase and decrease the rate of rotation of said gate and the discharge of materials thereby in direct relationship with variations in the hydrostatic pressures of the washing liquid.

5. In a device of the type described, the combination of a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquid through said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drive means for rotating said gate at a variable rate to control the rate of discharge of materials, of means for introducing a control fluid directly into the washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, pressure responsive means, means for establishing communication between said introducing means and said responsive means during like portions of successive pulsations of the washing liquid, pressure fluid operated means for varying the rate at which said gate is rotated by said drive means, a source of pressure fluid for operating said last mentioned means, and means operated by said pressure responsive means for varying the pressure of the fluid from said source to cause the pressure fluid operated means to increase and decrease the rate of rotation of said gate and the discharge of materials thereby in direct relationship with variations in the hydrostatic pressure of the washing liquid.

6. In a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow ofwashing liquid through said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drive means for rotating said gate at a variable rate to control the rate of discharge of materials, of a pipe for continuously introducing compressed air directly into the washing liquid at a point near the bottom of said bed, and at pressures varying in proportion to the hydrostatic pressure of the washing liquid at said point, a first expansible chamber in fluid communication with said pipe during like portions of successivepulsations of the washing liquid, a second expansible chamber operatively associated with said drive means for varying the rate at which said gate is rotated to vary the material discharge rate in direct relationship with the pressure in said second chamber, a source of pressure fluid connected to said second expansible chamber, a bleed-off valve associated with said source forvarying the pressure of the fluid in said second expansible chamber,

1-2 and means. operatively connecting said first expansible chamberand said bleed-ofi valve to cause the latter to vary the pressure in said second chamber in a direct relationship with variations in the first chamber.

7. In a device of the type described, the combinationv with a wash box having a bed of materials therein adapted,

to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquid through said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drivemeans for rotating said gate at a variable rate to control, the. rate of discharge of materials, of a pipe for continuously introducing compressed air directly into the washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressure of the Washing liquid at said point, a pressure measuring device in communication with said pipe during like portions of successive pulsations 015 the. washing liquid, a pressure fluid operated. control device. for varying the rate at which said gate is rotated by said drive means to..vary the material discharge rate in direct relationship with the pressure of the fluid applied to said control device, tubing connecting said control device to a source of fluid pressure, a.bleedoff valve in said tubing for varying the pressure of the fluid applied to said control device, and means actuatedbythe operation of said pressure measuring device for adjusting the position of said bleed-01f valve to maintain a direct relationship between the pressure of the fluid applied to said control device and said hydrostatic pressure of the washing liquid.

8. In a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing. liquid through said bed of materials, a rotary gate for discharging materials from said box, and continuously operating drive means forrotating said. gate at a variable rate to control .the rate of discharge of materials, of a pipe for continuously introducing compressed air directly into the washing liquid at a point near thebottom of said bed and at pressures varying in proportion to the hydrostatic pressure. of the washing liquid at said point, a pressure gauge in communication with said pipe during like portions of successive pulsations of the washing liquid, a casing having a movable wall operatively connected to said drive means for varying the rate of rotation of said gate to vary the material discharge rate in direct relationship with the fluid pressure in said casing, tubing connecting said casing to a source of fluid pressure, a pressure fluid operated bleed-cit valve in said tubing for varying the pressure of the fluid in said casing, tubing for supplying pressure fluid to operate said valve, said last mentioned tubing having a pressure regulating vent therein, and a closure operated by said gauge to adjust the size of said vent in accordance withthe pressure in said pipe, the size of said vent determining the position of the bleed-off valve and thereby regulating the pressurein said casing.

9. In a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquid through said bed of materials, a rotary gate for discharging materials from said box, a continuously operating prime mover, and transmission means including an adjustable throw step-by-step drive between said prime mover and said gate for rotating the latter at a variable rate to control the rate of discharge of materials, of means forintroducinga control fluid directly into and against the pressure of the washing liquid at a point at which pressure'of the washing liquid varies proportionately with changes in the hydraulic resistance of the material bed, means for amplifying the pressures of the control fluid in said introducing means during like portions of successiv'ev pulsations of the washing liquid, and pressure fluid'operating means responsive to variations in said amplified "pressures for varying the "length or throw of said step-by-s'tep drive to increase or decrease the rate st'ep-by-step drive between said'p'rime mover and said gate for rotating the latter at a variable rate to control the rate of discharge of materials, of means for introducing a control fluid directly into and againstthe pres sure of the Washing liquid at 'a point 'a't which'the pressure of the washing liquid varies proportionately with changes in thehydra'ulic resistance of the material bed, means for amplifying the pressures of the control fluid in said introducing means during like portions of successive pulsations of the washing liquid, means for further amplifying the previously amplified pressures of 'the control fluid, and pressure fluid operated means responsive to variations in the further amplified pressures for varying the length of throw of said step-by-step drive to increase or decrease the rate of rotation of said gate and the rate at which materials are discha'rgedby the gate in direct relationship with variations in the hydraulic resistance of the material bed.

11. In a device of the type described, the combination 'with a wash box having a bed of materials'therein adapted to be acted uponby a body of washing liquid, means for producing *avpulsatingflow of washing liquid through said bed of materials, a rotary gate for discharging materials from said box, a continuouslyoperating prime mover, andtra'nsmission'means'including an adjustable throw step-by-step drive between said prime mover and said gate for rotating the latter at a variable rate to control the rate of discharge "of materials, of means for introducing a control'fluid directly into the washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, a fluid pressuregauge, tubing connecting said introducing means and said gauge during like portions of successive pulsations of the washing liquid, pressure fluid operated means for varying the length of throw of said step-by-step drive in direct relationship with the pressure of the operating fluid, a source of pressure fluid for operating said last mentioned means, means including a valve for controlling the pressure of the fluid from said source, and a linkage connecting said gauge and said pressure controlling means for operating the latter to vary the pressure of the operating fluid in response to variations in the pressure measured by said gauge.

12. In a device of the type described, the combination with a Wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquid through said bed of materials, a rotary gate for discharging materials from said box, a continuously operating prime mover, and transmission means including an adjustable throw step-by-step drive between said prime mover and said gate for rotating the latter at a variable rate to control the rate of discharge of materials, of a pipe for continuously introducing compressed air into said washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, a pressure gauge, tubing connecting the gauge to said pipe, a valve in said tubing, means for closing said valve during like major portions of successive pulsations of the washing liquid, pressure fluid operated means for varying the length of throw of said step-by-step drive in direct relationship with the pressure of the operating fluid, tubing for supplying pressure fluid 't'ooperate said drive adjusting means, a valve in said-supply tubing for adjusting the pressure of the operating fluid, and means operated by said pressure gauge 'for regulating the position of said last mentioned valve to vary the pressure of the operating fluid and to cause the drive adjusting means to increase or decrease the rate of rotation of said gate in direct relationship with the variations in thepressure of the air in said pipe.

13. ha device of the type described, the combination with a Wash box having a bed of materials therein adapted to be acted upon by a body of Washing liquid, means for producing a pulsating flow of washing liquid through said bed or materials, a rotary gate for discharging materials from said boX, a continuously operating prime mover, and transmission means including an adjustable throw stepby-step drive between said prime mover and said gate for rotating the latter at a variable rate to control the rated discharge of materials, of a pipe for continuously introducing compressed air into said washing liquid at apoint near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, a pressure gauge, tubing connecting said gauge to said pipe, a valve in said tubing, means for closingsaid valve during like major portions of successive pulsations of the washing liquid, a chamber having a movable Wall the position of which is determined by the pressure of the fluid within the chamber, a rod connecting said movable wall to said step-bystep drive to adjust the length of throw of the latter in accordance with the position of the movable wall, tubing for supplying pressure fluid to said chamber, a valve in said supply tubing for controlling the pressure of the fluid in said chamber, and means operated by said gauge for regulating the position of said last mentioned valve to increase or decrease the rate of rotation of said gate in direct relationship with the variations in the pressure of the air in said pipe.

'14. In a device of the type described, the combination with a wash box having a bed of materials therein adapted to be acted upon by a body of washing liquid, means for producing a pulsating flow of washing liquidthrough said 'bed of materials, a rotary gate for discharging materials from said box, a continuously operating prime mover, and transmission means including an adjustable throw stepby-step drive between said prime mover and said gate for rotating the latter at a variable rate to control the rate of discharge of materials, of a pipe for continuously introducing compressed air into said washing liquid at a point near the bottom of said bed and at pressures varying in proportion to the hydrostatic pressures of the washing liquid at said point, a pressure gauge, tubing connecting said gauge to said pipe, a valve in said tubing, means for closing said valve during like major portions of successive pulsations of the washing liquid, a chamber having a movable wall the position of which is determined by the pressure of the fluid within the chamber, a rod connecting said movable wall to said step-by-step drive to adjust the length of throw of the latter in accordance with the position of the movable wall, tubing for supplying pressure fluid to said chamber, a fluid pressure operated valve in said supply tubing for controlling the pressure of the fluid in said chamber, tubing for supplying pressure fluid to said last mentioned valve, a valve in said last mentioned tubing for controlling the pressure therein, and means operated by said gauge for regulating the position of said last mentioned valve, the variations in the pressure of the air in said pipe acting through said gauge, valves, chamber and rod to increase or decrease the rate of rotation of said gate in direct relationship with variations in the hydrostatic pressure of the washing liquid.

15. A device for controlling the thickness of the high gravity stratum of the material bed in a Wash box, comprising means for discharging the high gravity particles from the lower portion of a material bed in a wash box,

means for actuating said discharge means to cause the latter to continuously discharge high gravity particles,

pressure fluid operated means having a member movable in direct relationship with variations in the pressure of the operating fluid for regulating said actuating means to proportionately vary the rate of discharge of the high gravity particles, means for supplying fluid at a variable pressure to said regulating means, means for continuously discharging compressed air directly into the bottom portion of the high gravity stratum of the material bed and at pressures varying in proportion to the variable hydrostatic pressures at the point of discharge, and means responsive to variations in the pressures of the air in said discharge means for adjusting said fluid supply means to vary the pressure of the fluid supplied to said regulating means in direct relationship with the pressure variations in said air discharge means. 16. A device for controlling the thickness of the high gravity stratum of the material bed in a wash box, comprising means for discharging the high gravity particles from the lower portion of a material bed in a wash box, means for actuating said discharge means to cause the lat- "ter to continuously discharge high gravity particles, means for regulating said actuating means 'to control the rate of discharge of the high gravity particles, a pipe for con tinuously discharging compressed air directly into the bottom of the high gravity stratum of the material bed and at pressures varying in proportion to the variable hydrostatic pressures at said point, means for amplifying the pressures of the air in said pipe, means for adjusting said regulating means to increase or decrease the rate of discharge of the high gravity particles to its maximum and minimum values, respectively, and to a plurality of intermediate values, and means responsive to variations in said amplified pressures for operating said adjusting means to vary the rate of discharge in direct relationship with variations in said hydrostatic pressures.

17. A device for controlling the thickness of the high gravity stratum of the material bed in a wash box, comprising means for discharging the high gravity particles from the lower portion of the material bed in a wash box, means for actuating said discharge means to cause the latter to continuously discharge high gravity particles, means for regulating said actuating means to control the rate of discharge of the high gravity particles, a pipe for continuously discharging compressed air directly into the bottom portion of the high gravity stratum of the material bed and at pressures varying in proportion to the variable hydrostatic pressures at said point, means for amplifying the pressures of the air in said pipe, fluid pressure operated means for adjusting said regulating means to increase or decrease the rate of discharge of the high gravity particles to its maximum and minimum values, respectively, and to a plurality of intermediate values, and valve means responsive to variations in said amplified pressures for varying the fluid pressure applied to said adjusting means to cause the rate of discharge to be varied in direct relationship with variations in said hydrostatic pressures.

18. A device for controlling the thickness of the high gravity stratum of a material bed in a wash box, comprising means for discharging the high gravity particles from the lower portion of a material bed in a wash box, means for actuating said discharge means to cause the latter to continuously discharge high gravity particles, pressure fluid operated means for regulating said actuating means to control the rate of discharge of the high gravity particles, apipe for continuously discharging compressed air directly into the bottom portion of the high gravity stratum of the material bed and atpressures varying in proportion to the variable hydrostatic pressures at said point, tubing connecting said pipe to a source of compressed air, means mounted invsaid tubing for maintaining the rate of flow of air into said pipe at a constant value, tubing connecting said pressure fluid operated means to said source of compressed air, and means associated with said last mentioned tubing and responsive to the pressures of the air in said pipe for adjusting the pressure of the air delivered to said pressure fluid operated means to increase or decrease the rate of discharge by amounts that are directly proportional to variations in said hydrostatic pressures.

References Cited in the file of this patent UNITED STATES PATENTS Brentz Oct. 27, 1942 Lotz Aug. 12, 1952 7 Inc., Albany, New York, 1947, pages 54-76. (Copy in Division 30.)

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