US2667974A - Heavy cyclical centrifugal machine - Google Patents

Description

Feb. 2, 1954 J. HERTRICH 2,667,974

HEAVY CYCLICAL CENTRIFUGAL MACHINE Filed June 14, 1949 7 Sheets-Sheet l INVENTOR. Jasepu HE/VTfi/[H QMM W Feb. 2, 1954 J. HERTRICH 2,667,974

HEAVY CYCLICAL CENTRIFUGAL MACHINE Filed June 14, 1949 7 Sheets-Sheet 2 BYW.

Feb. 2, 1954 J. HERTRICH HEAVY CYCLICAL CENTRIF'UGAL MACHINE '7 Sheets-Sheet 3 Filed June 14, 1949 Ill/ll, i A

INVENTOR.

Just/ x4 A 'FT/P/L'H HTTUHA/EYS J. HERTRICH HEAVY CYCLICAL CENTRIFUGAL MACHINE Feb. 2, 1954 7 Sheets-Sheet 4 Filed June 14, 1949 H 2 m fl W E, w J V. B

/7 7 THE/V575 Feb. 2, 1954 J. HERTRICH 2,657,974

HEAVY CYCLICAL CENTRIF'UGAL MACHINE Filed June 14, 1949 7' Sheets-Sheet 5 INVENTOR. Jasa y HEFTR/[H Feb. 2, 1954 R c 2,667,974

HEAVY CYCLICAL CENTRIFUGAL MACHINE I Filed June 14, 1949 7 Sheets-Sheet 7 Patented Feb. 2, 1954 UNITED STATE-S PATENT H'EA'VY CYCLICAL CENTRIFUGAL MACHINE Joseph Hertr'ich, Hamilton, Ohio, assignor to The Western States 'MachinefCompany, Hamilton, -0hio,-'a corporation of Utah Application June '14, 1949, 'SerialNo. 99,040

15 Claims. I

This invention relates to new and improved heavy cyclical centrifugal machines and'elements thereof of the type used for separating liquid from solids in large scale industrial processes such as, for example, the manufacture, refining or drying of sugar, dextrose or other suitable crystalline or granular solids.

Centrifugals of that type are known in which the treatments effected in each spinning period are controlled adjustably by timing mechanisms which automatically coordinate actions of driving, spraying (washing) and braking elements in each cycle. Still, the steps necessary for discharging the basket are commonly performed under manual control, for lack of safe, reliable and efficient means of performing them otherwise.

When the centrifugal is stopped after a spinning period the treated solids generally stay in the basket as a more or less hard wall that must be dug out by rotating the basket slowly, preferably at about 40 to 60 R. P. to force this wall against the tip or working end of a mechanical discharger shoe while the latter is pressed into the solids. Lowering 'of the shoe into the basket and its digging movements must be effected by an attendant, who usually must also engage the centrifugal drive so as to obtain a suitable slow basket rotation.

Discharging in this manner not only is timeconsuming and costly but also is a source of serious hazards in the use of the machine. Damage to basket lining screens and bending or breaking of dischargers are fairly common occurrences where fine-grained coherent solids must be discharged after having been subjected to very high centrifugal forces. The hardness of the wall they form often induces the attendant to work the discharger too strongly, or to rotate the basket too fast, with the effect of cutting into or actually digging out the basket linings as Well as the treated solids.

Much greater hazards exist in the possibility of the discharger engaging the basket or matetrial in it while it is spinning at high "speed.

Despite all reasonable precautions commonly taken, a discharger still can fall or be moved inadvertently into the spinning basket. Whenever this occurs the basket, the discharger and various other parts are likely to disrupt, and serious injuries or even death may result to persons in the vicinity of the machine.

An important object of this invention is to provide a manner of heavy centrifugal construc'ztion and operation which is absolutely safe and foolproof against the occurrence-of accidents in' discharging.

Another object is to provide a safeand'efficient centrifugal of the heavy-duty cyclical type which performs the operations attendant to discharging automatically in proper sequence ans-at freely adjustable intervals; and, further, to pro vide such a machine in which those operations are coordinated automatically and safely with automatic control of other operations occurring in each centrifugal cycle.

A further object of this invention is to provide an improved driving system for bringing and holding the basket to a constant low speed suitable for mechanically discharging treated solids.

Another object is to provide an 'eflicient poweroperated discharger suitable for centrifugals of the type described, and one which not only is safe and foolproof in use but which also "acts with precision and is organized so compactly that it occupies no greater part of the available space at the machine than doconventional m'anually operated dischargers.

Still another object of this invention is to providean eificient mechanism for lifting and lowering a basket bottom valve in connection with each discharging operation, and, more .particul'arly, to provide a valve lifting mechanism which operates with a minimum of motion and which can be held permanently inside the centrifugal basket from a mounting above the basket without obstructing any of the other elements or functions of the machine.

According to an important feature 'of thisinvention, I have discovered that the. hazards and difiiculties connected withdischarging centrifugals of the type described can be "overcome by rotating the centrifugal basket in one direction to and from the full speed employed in the process or spinning .period of each cycleand rotating the basket in the opposite direction after the normal deceleration to bring it to a low negative speed for. operation of a mechanical solids discharger. The deceleration of the basket in each cycle thus is carried in normal direction all the way to zero speed, and from zero speed reverse rotation ensues until the basket reaches a desired negative speed at which the discharger is brought into operation.

For this purpose the driving system of the machine may be equipped not only with the usual prime mover 'or main slip drive operative in nor-- mal direction but also with a suitable driving element or slip driving system operative upon the basket-shaft at a constant low speed in reverse direction. The discharger is used in the reverse of normal arrangement, with its shoe extending toward solids in the basket in the direction of the normal basket rotation, i. e., so that it can act to dig out solids only while the basket is rotated in reverse direction. It results that the discharger shoe can never engage itself into the wall of solids as long as the machine is spinning in normal direction, and even a deliberate movement of the shoe into the spinning charge is impossible due to a rejecting action of the charge along the back side of the shoe. On the other hand, the reverse basket rotation following each spinning period renders the discharge fully operable in the usual way, though at no hazard because the reverse rotation serves only for discharging and is definitely limited to a safe low speed.

According to another feature of this invention, a low speed slip drive including a pressure-activated friction clutch, an operative at a constant low speed suitable for discharging, is provided in connection with a basket shaft driven to high speed for spinning operations by a suitable prime mover, the low speed slip drive being activated at a suitable interval after each period of action of the prime mover. This makes it no longer necessary to decelerate the spinning basket in each cycle to a speed below a critical low limit before activating the low speed drive, because the low speed drive can act safely on the basket shaft at any speed of the latter within a wide range, and its slip action will bring the basket positively from any such speed to its own constant discharging speed. In addition, such a low speed drive may have a driving friction member that engages gradually with its driven member, so that a small motor driving and activated simultaneously with the former can reach its full rotational speed before becoming burdened by the load it must sustain. A further important advantage of such a system is that the low speed drive motor can be selected large enough to bear any loads to which it might be subjected in uses of themachine, while the actual low speed driving torque desired for any particular use, depending upon the type of solids to be discharged and the manner of discharging them, can be obtained readily by simple adjustment of the clutch-activating pressure. And with such a system a group of similar machines can utilize a common low speed drive motor on a line shaft, if desired.

Furthermore, through use of the negative speed 'discharging'system here disclosed it becomes possible with' complete safety to leave any discharger shoe inside the basket during all the operations of the machine, and that in turn gives such a simplification of the motions and mechanisms required for discharger operation that an emcient power-operated discharger can be provided which Works with greater precision than known dischargers, frees an attendant from the heavy effort of discharging and makes it possible to provide an exceedingly practical automatically discharged cyclical centrifugal machine.

Since the discharger shoe can be held inside the basket at all times with safety, there is no necessity for removing it to keep it in a safe place outside the basket during spinning periods. Therefore, only two types of motion are required for the shoe. One is a swinging motion radially outward toward and inward from the basket side wall, and the other is an axial or vertical motion between the ends of the basket. These motions both have definite limits for any particular size of centrifugal basket; so they can be brought about simply by use of fluid pressure cylinders having plungers that move in definite strokes corresponding to the required distances of shoe travel, or by gear motors having definite limits of movement, and no complex mechanisms or special safety arrangements are needed for governing the travel of the shoe.

A power-operated discharger constructed according to these principles constitutes a further feature of this invention. This discharger preferably is operated by fluid pressure and made with a built-in damping device acting to absorb shocks and retard the horizontal outward motion of the discharger shoe as the shoe approaches the basket lining, thus obtaining smooth discharging at a controlled rate. The fluid flow controlling the discharger movements preferably is throttled to obtain desired rates of horizontal and vertical shoe movements. Further. a latch arrangement is provided which underlies the shoe in its idle position at the inward and upward limit of its travel and keeps it from dropping downward in the basket under any circumstances until after it has been moved horizontally outward to a position where it will have entered the Wall of any charge in the basket.

According to another feature of this invention, the centrifugal. is provided with a power-operated discharger and with a deviceconnected with discharger controls which acts automatically to hold the discharger inoperative except at safe low speeds of basket rotation. This device may be a speed responsive device driven with the basket shaft, and in combination with the negative speed discharging system it may be a speed switch acting to energize discharge timing controls as the speed of the decelerating basket approaches zero in each centrifugal cycle. Upon the action of such a device the discharge or low speed slip drive may first be caused to operate on the basket shaft, and the discharger itself may then be activated in due time, when the basket has reached the desired discharging speed.

According to other features of this invention, the basket bottom opening which forms an outlet for discharged solids is provided'with a vertically movable valve of special form, and a device for lifting and. lowering this valve is provided inside the basket with a swinging arm which removes the bottom valve efficiently from the outlet and disposes it in a tilted relation to the basket shaft such that it cannot obstruct the operation of the discharger or the rotation or discharging of solids in the basket. The valve lifting device may be of simple construction, by reason of the form and motion provided for the valve assembly. It can be operated efficiently by fluid-pressure means, and its operation may be controlled by elements coordinated with elements automatically controlling the discharger operations so that the bottom valve will be lifted automatically before the discharger shoe is brought into action and will be lowered automatically after the discharger has ceased operating.

According to another embodiment of the invention, the discharge drive of the machine may be made to serve not only for bringing and holding the basket to a constant discharge speed but also as a brake for effecting a large part of even all of the deceleration from high speed, thus eliminating controls and steps otherwise incident to a switch-over from braking to low speed driving elements and making it unnecessary to have the usual friction brake on the machine. For this Tpurpose a low speed slip drive operative on the basket shaft at a constant discharging speed'may be constructed as a heavy-duty agency that can absorb and dissipate the heat of braking and may be activated in each cycle at the time of action of the usual friction brake. Through its action the deceleration stage of each cycle merges continuously into the discharge driving stage, without any interruption or intervening agencies. The action of such a combined brake and discharge drive maybe started at the end of full speed rotation of the basket if the centrifugal has no regenerative braking facilities, or after an interval of regenerative braking from full speed if the prime mover of the machine is an electric motor having regenerative braking facilities. In some cases, the combined brake and discharge drive may itself be a regenerative braking system.

Other objects, features and advantages of the invention will appear from the following detailed description and the accompanying drawings of illustrative embodiments thereof.

In the drawings:

Fig. 1 is a side elevation of an assembled centrifugal machine embodying this invention, some parts being broken away and some being shown in vertical cross section;

Fig. 1A is a fragmentary front elevation from line IA'IA of Fig. 1, showing schematically a suitable assembly of certain control elements of the machine; I

Fig. 2 is a fragmentary plan view along line 2-2 of Fig. 1, with some parts broken away and some in horizontal cross section, showing the assembly of the basket with its surrounding stationary curb and with the discharger, the valve lifter and the sprayer of the machine;

Fig. 3 is an elevation of one side of the discharger in assembled relation to the basket and curb which appear in vertical cross section;

Fig. 4 is an elevation, partly in vertical cross section, of the opposite side of the discharger mechanism;

Fig. 5 is a horizontal cross section through the discharger mechanism along line 5-5 of Fig. 3, with parts of the basket and 'curb top broken away to show the shoe inside the basket;

Fig. 6 is a side elevation of a suitable dischairger shoe, showing its connection with a plunger which moves it up and down; t

Fig. 7 is a fragmentary longitudinal vertical section through the discharger mechanism as viewed from the side seen in Fig. 3;

Fig. 8 is a transverse vertical section through the discharger mechanism along line 3-8 of Fig. 7;

Fig. 8A is a cross section of an air flow control;

Fig. 9 is a partial elevation andpartial vertical cross section of the assembled basket valve and valve lifting device;

Fig. 10 is a fragmentary plan view of the same assembly with the lifting arm in position to start raising the basket valve;

Fig. 11 is a partial elevation and partial vertical cross section of the same assembly, showing the lifting arm in idle position and also in a broken line position which it occupies during operation of the discharger; I M

Fig. 12 is a vertical section through the low speed or discharge drive at the top of the main driving motor of the machine;

Fig. 13 is a fragmentary plan view showing parts of a zero speed switch assembly as viewed from line l3-l3 of Fig. 12; r

Fig. 14 is a horizontal cross section along line l4+l4 of Fig. 12; a

Fig. 15 is an elementary wiring diagram showing the control of the illustrated-machine;

Fig. 16 is a wiring diagram for its driving system; and

Fig. 17 is a diagram of control, timer and -mo=- tor contactorrelay panels.

As seen in the drawings, a large centrifugal basket I having a perforated side wall 2; cap '3 and bottom 4 is carried by the lower end of a vertical driving shaft or spindle 5 which is suspended in gyratory manner from a suitable head 6 supported by a hanger structure I from framework F. All of this is known. A large electric motor MM is shown as the prime mover of the machine, preferably of the squirrel-cage induction type, although other suitable drives could-be used. The shaft of motor MM is connected directly with shaft 5 through structures in the head 6, in known manner. i

The prime mover is operative up o'nthe basket shaft in clockwise direction as viewed from above in Figs. 1 and 2; so when it is activ the basket is rotated in normal direction as indicated by the Spin arrow of Fig. 2. That normal rotation continues to and at the full centrifuging speed -set by the motor characteristics and also while the basket is decelerated to terminate each spinning period. p

The deceleration preferably is brought about in this embodiment by a combination of regenerative braking and friction braking, although friction braking alone can be used if desired. For regenerative-braking motor MM is made with both high speed (say 1800 R. P. M.) and low speed (say 900 R. P. M.) windings which are energized, respectively, through contacts H-and L (Fig. 17) by controls to be described hereinafter. It is sufficient now to mention that the motor is switched from high to low at the end of the desired period of full speed operation, so that a suitable interval of regenerative braking ensues under retarding action of the low speed motor field. At the end of that interval, the motor is completely denergized and friction braking ensues to complete the normal deceleration of the basket. For friction braking, a brake drum 8 is carried with the basket shaft assembly, and friction bands 9 are movable against the drum by action of connected air cylinders ID. In known manner, the bands normally are held free of the drum by springs and are setby admitting air pressure to the cylinders through an air line H leading from a solenoid valve BSV (Fig.1A).

After each spinning period the treated solids held in the basket must be removed byjaction of a mechanical discharger. Around spindle 5 basket bottom 4 has a central opening 4a forming a solids outlet, while basket cap 3 has central opening 3a affording access to the interior of the, basket. A frusto conical valve 12 fitting outlet 4a surrounds shaft 5 and is movable vertically to expose the outlet during each discharging opera tion. The entire basket is surrounded by a stationary curb M which collects the liquid expelled during spinning periods and has a centrally open top l5 providing support for a discharger IS, a valve lifting device I l and a conventional sprayer H5 for washing solids spinning in the basket.

"The principal element of the discharger is a shoe 2!) carried on a vertical shaft 2| and movable inside the basket both vertically so that its tip or working end 22 can traverse the axial length of the basket between cap 3 and bottom t (see Fig. 3), and horizontally so that the tip 22 can move radially in and out relative to basket side wall 2 (see Fig.

It will be noted from Figs. 2 and 5 that the discharger shoe extends from its supporting shaft toward the basket side wall, 1. e., toward any wall of solids, in the basket, in the direction of the normal basket rotation which occurs during spinning periods. The'shoe can act to dig out solids only by rotation of the basket and its contents against the shoe tip, i. e., in the direction opposite to the lead of the shoe. The shoe cannot act during normal rotation of the basket, even though someone tried to engage it into a spinning charge,

because the solids spinning in normal direction would bear against the back side of the shoe and force it radially inward. The action of the discharger therefore must be brought about by reverse rotation of the basket in the direction indicated by the Discharge arrow of Figs. 2 and 5, and for this purpose the driving system of the machine is provided with a special low speed or discharge drive DD appearing above motor MM in Fig. 1 and Fig. 12,

According to the illustrated form, the discharge drive DD has a housing 31 mounted on the upper end of the main motor frame and providing lower and upper chambers 32 and 33, respectively. A friction clutch DC is in the lower chamber, and a connected speed reduction gear is in the upper chamber. The main motor shaft (not shown) has an extension or stub shaft 3% passing upward into chamber 32, to which is fixed spider 35 carrying a friction drum 33. Aligned with but separate from extension 34 is a stub shaft 31 held by bearing sets 38 and 39, respectively, in lower and upper walls of chamber 33. The lower end of stub shaft 3? carries a clutch wheel 40 in chamber 32 inside drum 35, and fixed around wheel 40 is a hollow expansible ring member 42 which carries external friction elements 4| to engage the drum. Expansible member 42 normally is deflated so that the friction elements iii do not engage drum 38, but when compressed air is introduced into member 42 it becomes inflated so as to engage th friction eiements against the drum with a force determined by the air pressure. An air line 23 leads to the interior of member 42 from a duct is in wheel 69 and a connecting axial duct 65 in stub shaft 37. with an air line 456 extending outside housing 3| to a discharge clutch solenoid valve DCSV (Figs. 1 and 1A) which may be controlled as described hereinafter. The valve DCSV generally is energized at the time of energizing the discharge drive motor DM. The resulting opening of the valve and flow of air necessary to expand member 42 to clutch-engaged position take an appreciable time which exceeds the time required for motor DMto reach its full speed; so the motor is never loaded until it is in condition to sustain its full load.

On stub shaft 31 inside chamber 33 is a worm gear 48 engaged by a worm 49 on worm shaft 49a. The worm shaft is held by bearing sets and 5! in housing 31 and projects outside the housing at one end 52 which is connected with a small motor DM. Such an arrangement enables permanent lubrication of the low speed drive gears without danger of oil leakage. Motor Axial duct 45 connects DM drives worth 49" at constant speed; thus driving the clutch member on stub shaft 31 at a constant low speed of about 40 to R. P. M. for operation of the mechanical discharger. The worm is driven, for example, through v belts '56 passing over pulley 55 on motor shaft 54 and pulley 51 on end 52 of the worm shaft. The discharge motor DM preferably is mounted on a base plate 58 swiveled at the bottom on a horizontal axis 59 and subjected to tension of spring 6i] at the top so that the tightness of belts 56 can be adjusted readily by means of a set screw 6 I.

The discharge motor thus rotates stub shaft 3'! and the friction elements ii in the direction of the arrow in Fig. 14, corresponding to the Discharge arrow in Figs.'2 and 5. Accordingly, the discharge drive is operative upon the basket shaft at a constant. low speed which is negative with respect to the normal basket rotationimparted by prime mover MM. Therefore, if the discharge drive is activated as basket l approaches or reaches the end of a normal deceleration, friction brake 9, being then released, the discharge drive will bring and hold the basket to a low negative speed suitable for operation of the discharger l6, and the discharger then may be operated efficiently to remove treated solids from the basket with complete safety.

The discharger l6 embodies several important features of construction and operation and is illustrated in detail in Figs. 3 to 8, inclusive. It is motivated entirely by'fluid pressure and springs which relieve the centrifugal attendant from all the physical effort heretofore required for discharging. The movements of the discharger shoe have definitely determined lengths, yet no limit switches or other complex safety devices are required at the limits of shoe travel. The required movements are produced at definitely controlled rates which can be set as desired to suit any conditions encountered in the use of the centrifugal. The discharger shoe is kept inside the centrifugal basket at all times,

7 yet with complete safety not only against engaging into spinning contents-of the basket but also against falling accidentally to the bottom of.

the basket. And the discharger is so compactly organized that it requires no extra space on the curb top and may even reduce the usual space requirement by having the shoe always inside the basket away from the curb top.

The operating mechanism of the discharger centers about a supporting stud 10 which projeots upward from a base plate or flange H bolted to the curb top :5. A bracket or housing 12 is mounted on stud Hi to swing horizontally about its axis, and extends from the stud toward shaft 5 to a vertical guide portion 13 which overhangs the inner edges of curb top is and basket cap 3 and receives slidably the upper end portion of the discharger shaft 25. Shaft 21 and its bearing in guide l3 are made with a square or other angular cross section so that the discharger shoe 2!) on shaft 2! cannot swing with respect to the housing, although it can swing with the housing on stud l6 and is also free to be moved axially up and down in its guide passage.

From Fig. *5 it will be seen that swinging movements of housing 12 and shaft 2i about stud It can dispose shoe 20 at the broken line or the full line position of Fig. 5 or at any intermediate position. These swinging movements are brought about and are limited to the desired extent as follows: Extending laterally from opposite sides of housing 72 are two slidable membersI4 and 15 having rounded abutment ends 14a and 1501., respectively, which face in opposite directions. These ends=are arranged to abut against fiat faces offixed .posts 16 and ii, respectively, which extend vertically fromopposite sides'of thebaseplate l'l. The slidable abutment member I is movable axially. ina bearing 78 on housing and against a diaphragm 15 which inturn is sealed across a transverse cavity 8| in the housing and held under the pressure of a spring 80in that cavity. Cavity 8I is filled with: oil. Inward movement of member 15 and diaphragmfiIS thus is cushioned by the body of oil in cavity 8|, and the oil under compression gradually escapes through an oil bleeding passage 82 which leads from thetop of cavity M (Fig. 8). During outward movements of member I5 and diaphragm 19 under the force of spring 88 the oil formerly-expelled fromcavity 8| returns through passage 82;

The other slidable abutment: member 4. extends throughand in sealed relation to a transverse bearing member 84 and has an inner end 141) within a pressure. chamber 85 inside the housing I2. Member. thus constitutes a piston, and it 'actsas such 'to swing thehousing and therdischarger shaft counterclockwise about stud 18 (Fig. 5) upon the admission of fluid pressure intochamber 85i For the latterpurpose, a duct 86 in the housing structure 'is connected with an airline B'Ileading toa solenoid-valve DSVI (Fig. 1A), so'that actuation of the valve to admit compressed air through line 81 .brings into chamber 85 fiuid pressure which forces housing l2 and abutment member I4 apart in directions transverse to the longitudinal axis between stud I8 and shaftiZI. Since the abutment-end I la engages against the fixed post :16; housing I2 must then movecounterclockwiseon stud I8 asseen in Fig. 5, and shaft ZI sWings with the housing so as to moveshoe' 28from its'broken line position toward its full line position. Before the shoe tip 22 reaches the basket side wall, however, abutment end 'ISa'engagesagainstfixed post II, so that the final outward movement of the shoe takes placeunder the retarding or dashpot effect ofmember 15 in cavity 8i. 1 An adjustable stop IIa fixed in post 'I'I'is engaged by part 12a on housing ?2 so as to limit the horizontal outward movement of the shoe tip.

On the other hand, when the pressure in chamber 85'is released, member 141s free to slide inward, and the discharger shoe swings radially inward from the basket side wall under the action" of spring 80 and the pull of a heavy tension spring 88 which has one end fixed to pin 89 onbase-plate II and has its other end fixed on eye'98 on the shaft guide I3.

The up and down-movements of the discharger shoe are brought about. entirely by action of an air cylinder 92 which is carried in vertical position alongside shaft 2| by'bracket flanges 83 fixed to guide 13.- Cylinder 92 has a plunger 94 extending downward to a detachable coupling at 95 with the body of the discharger shoe 28 (Fig. 6). The length of cylinder 52, i. e., the stroke of plunger 9% in it, is fixed so that when the plunger lies at the upper limit of its movement the dischargershoe 2%? will be heldjust-below the basketcap 3, as indicatedby broken lines in Fig. 3, while at the lower limit of plunger movement the shoe will lie just above the basket bottom it as seen in full lines in Fig. 3. The long cylinder 92 has upper and lower air inlets connected with compressed air lines Stand 91, respectively, which lead to a suitable solenoid valve DSV2 whereby pressure may be" admitted to either the upper or the lower endof the cylinder for moving the discharger shoe eitherdown or up.

The air flow through each of lines 8'5, 88- and 97 is retarded to a selected rate that will give the desired rate of attendant shoe movement. For this purpose, solenoid valves having adjusta-i ble air passages maybe used, but air flow cone trols as shown at .Siiazpreferably are placed in each line. These air flow controls areshown in detail in Fig. 8A, and as shown in Fig. .1A the ones in lines 87 and 96 are placed in. normal position while the one in line 91 is in reversed position. Each has a hollow cylindrical body. I48 containing in one end a plug I42 which is bored ax-iallyand holdsfa removable restricted orifice member I i-3. The other end presents an internal annularseat I44 for a non-metallic valve disc I45 carried by a plunger I46insidethe body. A spring I4I presses the plunger to seated posi-. tion. The plunger has a central cavity packed with an air filtering medium I48 and a removable member I49 having a smallzorifice I58-normally completes the air passageway throughthe valve;

The orifice in member I43 and orifice I58 to-' gether control the speed of airflow through the control in the direction from 143- to I44, while air flow in the opposite direction-is controlled only by the orifice in I43 since such air flow displaces plunger I46 from its seated-position and allows orifice I 58 to be by-passed betweenthe sides of the plunger and body I48. It results that compressed air passing fromDSVI- to chamber fioWs-at a rate determinedbythe sizes selected for the two orifices, which thus regulate the rate of horizontal outward movement ofshoe 28, while the rate of inward movement of theshoe'also is limited, duringthe return of plunger 14 into chamber 85 under action of spring 88, by the action of orifice 143: than orifice I58. The flow through line pro ducing downward'movement of the'shoe is con-: trolled similarly, and similarlimitation is placed on the back fiowthrough line96- attending upward movement of the shoe. The control in line 91 being in reversed arrangement, the rate of airflow through that line from DSVZ is regulated only by the restrictions ofan orifice I43, while the back flow asthe shoe is moved downward is restricted by two orifices I43 and I58.

On the downward strokeboth restrictionsin each of the air lines 96 and 9? are effective, the restrictions in line 9'! actually being predominant in their effect, while on the upward stroke only a restrictionat I43 is effective in each line and the .one in line 96 is predominant, In this way the discharger shoe. is moved at a relative low speed in downward direction, in order to limit the depth of charge removed in each revolution of the basket, while the upward motionof the shoe occurs at a faster rate inzorderto save time, that rate, however, being limited to one that prevents shocks. For. example, the time forthe downward stroke may be from. about 8 to 16 seconds while the time for the upward stroke may be from about 1 to 3 seconds.

As further illustrated in.Fig..3, the base plate II has a portion lflllwhich overhangs the inner edge of the curb top and towhich a bracket. II is fixed so as to extend downward into the basket. At its lower end this bracket forms a horizontal ledge I02 directed toward thedischargerv shaft 2 I. Ledge I82 is located just below the bottom of shoe 28 when theshoe is in its raised position. Accordingly, when the shoe is down, and the discharger is swung radially inward by spring 88,

This generally is larger the side of shaft 2I abuts slidably against the end of ledge W2. Pressure acting in the lower end of cylinder 92 then moves the shaft 2I upward along the ledge end until the shoe has reached its upper position, whereupon a final inward swinging occurs to place the base of the shoe over the face of the ledge. That is the idle position of the discharger, from which it cannot fall toward the bottom of the basket even though the upward pressure in cylinder 92 be released.

When the discharger is to be operated the discharge drive is adjusted to bring the basket to its low negative speed, the basket bottom valve I2 is lifted to expose outlet 4a, and when the discharge speed has been reached air pressure is admitted into chamber 85 from valve DSVi. The shoe tip 22 then swings slowly outward into material in the basket and continues this movement as the material is rotated against it until it reaches the basket side wall. Meanwhile, it has moved clear of ledge I02. Having'thus dug a complete swath from the top of the wall of solids, the shoe now is ready to move downward and dig out theremainder of that wall, which is accomplished by admitting pressure into the upper end of cylinder 92 through valve DSV2. At the limit of the downward movement, valve DSVI is actuated to release the pressure from chamber 85; the shoe swings radially inward under spring force to assume the position limited by abutment of shaft 2| against ledge I02; and then pressure is shifted from the upper end to the lower end of cylinder 92 to raise the shoe to its idle position. It will be understood that in and out movement of the shoe may be brought about at any position in its vertical stroke by simple actuations of valve DSVI.

The incorporation of what has been described into an automatically discharged machine involves further provisions for bringing the discharge drive into action at the end of each spinning period, lifting the basket bottom valve (unless the basket used has a loading cone on its shaft and no bottom valve), actuating the discharger, lowering the bottom valve, inactivat-.

ing the discharge drive, and stopping the reverse basket rotation, all in proper coordination; and for automatic control of the steps occurring in each running period, the prime mover, the sprayer (if any), and the brake also must be combined into the same control system.

For the purpose of activating the discharge drive and other elements connected with discharging, a switch device responsive to the speed of the basket shaft is shown at ZS in Figs. 1, l2 and 13. This preferably is a rotary switch unit of known construction referred to as a zero speed switch, which is actuated in response to deceleration of its speed of rotation, so as to shift a control contact or contacts when the speed of rotation of its shaft III approaches zero. It is rotated with basket shaft 5 through a V-belt H4 running over pulley H2 on shaft III and pulley I I3 fixed to the hub of spider on the main motor shaft extension 34.

As a safety feature assuring proper coordination of the operations controlled through the speed switch, that device preferably is mounted on a bracket H5 which is swiveled on a vertical pin I it held by parts of housing 3! and is pulled about the axis of pin H6, in a direction to tension belt H t, by the action of a spring II! fixed at one end to bracket H5 and at the other end to an eye IIS on housing 3|. Bracket IE5 carries a limit switch LS having a swiveled arm I I9 which bears against structure of housing (H in such manner that, if belt I I4 should break or slip from a pulley, spring II'I' would pull the bracket assembly and move arm I I9 to a cutoff position indicated by broken lines in Fig. 13., That movement opens a control contact LS2 in limit switch LS to inactivate the driving system and closes a control contact LSI to set the brake of the machine by energizing relay BR to BSV (Fig. 1 and thus admitting air pressure through BSV and line II to the brake-setting cylinders ID.

Lifting and lowering of the basket bottom valve I2 are accomplished through the valve lifter I! which appears in detail in Figs. 9 to 11. The bottom valve I2 is formed at the top with an annular flange I20 which is curved downward at its periphery to form an annular recess I2I in which the laterally-offset protruding end I22 of a lift-' ing arm I23 may be engaged. Arm I23 normally hangs vertically from a fulcrum pin I26 which is seated in a supporting lug I25 embraced by bifurcated ends I26 and I2'I on the arm; Lug I25 is integral with a supporting tube I28 which extends downward into the basket from a mounting plate In on part I5a' of the'curb top. The fulcrum point of the lug is offsetlaterally and downwardly from the open end of tube I28, and the bifurcated ends I26 and I2! extend backward from pin I24 at an angle to arm I23 so as to terminate at a point below the open end of the tube. At that point a pin I30 joins ends I25 and I2l'pivotally to the lower end of a connecting rod I3I which extends vertically in tube I23 to a pivotal connection at I32 with an air cylinder plunger I33.

The air cylinder itself appears at I34 and is mounted above plate I29. Air lines I35 and I35 lead into its upper and lower ends, respectively, from a solenoid valve VLSV through which the lifting and lowering movements of the basket bottom valve are controlled. Upon actuation of VLSV to admit pressure into the upper end of cylinder I34, plunger I33 and connecting rod I3I move downward and thrust the lifting arm I23 from its idle position, shown in full lines in Figs. 9 to 11, to its working position shown in broken lines in Fig. 11. As the arm moves to the working position its protruding end I22 engages in recess I2I under flange I23 and lifts the frusto-conical valve I2 to a tilted raised position exposing the basket bottom outlet M, as indicated diagrammatically in Fig. 11 and by full lines in Fig. 1.

The lifting movement of the bottom valve disposes it mostly on the side of shaft 5 away from the discharger shoe 20 so that there is no obstruction to the operation of the discharger, to the wall of solids in the basket or to the passage of solids out of the basket. The basket shaft 5 has a swelled portion 5a inside cone valve I2 and tapered inwardly at the top 51). Under lifting action from arm I 23 at its back side (away from the discharger shoe), the valve slides and tilts on the taper so as to become unobstructive after only a small distance of movement. When the air control valve VLSV is actuated to shift pressure from the upper to the lower end of cylinder I34, the arm I23 is drawn back to its idle position where it hangs below part I5a of the curb top, and the cone valve is guided back to its closed position on the conical taper 5b. In that position the valve lifter is quite free of the bottom valve, enabling the latter to be moved freely by hand if desired, and it is also away from the zone of action of the sprayer I3, from the orbit of material in the basket I, and

from-the path of .charge-Vmaterial entering the basket during a loading operation.

The sprayer-l8 has a fluid'line 18w leading from solenoid valve WWSV (Figp-lA), through which a suitable washing fluidunder pressure may be delivered to the sprayer nozzles whenever WWSV is energized."

The control system of the illustrated-machine includes elements for manual control of its func tions and also a systemof automatic control by which all the operationsexcept those connected with starting each cycle are normally brought about automatically in desired sequence. The various control elements utilized may be of any suitable construction and are known per se.- As diagrammed, they include push-button switches on a panel PI and the several solenoid valves with pressure-regulators on control framing CF, all available to an attendant .at the machine (Figs. 1 and 1A),.and electrical control'relays; timers and motor contactors on remote control panels P2 and P3 (Fig. 1'7) at some other con venient location; The control elements are' interconnected electrically for operation'in the re-' lationships indicated bythe wiring diagram of Fig. 15. In that diagram relay contacts are shown separately from the coils by which they are opened or closed, in order to indicate their functions clearly; The contact or contacts belonging to'a certain relay'are designated, however, by corresponding reference characters with orzwithout suffixed numerals to distinguish between different contacts of the same relay.

Pushbuttons at Pl closeor open control circuits directly when pushed. These includebuttons:

S, for manually stopping the machine at any time;

RS, for resetting the 'automatic controls before starting a new cycle;

R, for starting a running'or spinning period of the machine;

J, for manuallyjogging or holding main motor MM on its low speed winding to obtain a suit-' able loading speed;

L, for activating the discharge drivemanually;

DBI, for manually'actuating valve DSVI to swing the discharger outward and inward;

DB2, for manually actuating valve DSVZ to move the discharger down and up; and finally W, for manually actuating valve WWSV to deliver washing fluid'through the sprayer, this occurring through controlrelay WR and its con-' tact WRI'.

The contacts of pushbuttons S and RS are normally closed, as shown in Fig. 15, 'while those of pushbuttons R, L, J, 'W, DBiand DB2 are normally open. Valve WWSV is a two-way solenoid valve on a washing fluid supply line (not shown). Valves DCSV, DSVI and BSV are threeway air solenoid-valves connected with a common compressed'air header H0, each'having an energized position connecting the header with the air line from the element controlled by' the valve, as wellas' a deenergized position connecting that air line to a vent. The valves DSVZ and VLSV are four-way air solenoid valves connected with header H0, each'having two air lines from the element'it controls and serving in either position to connect one of these lineswith the header while venting the other line'tothe atmosphere. Thus, when DSVZ is energized it transmits air pressure to the upper end of cylinder '92 to move the discharger shoe downward, while when it is deenergized the air pressure is released from-the 14 upper end and transferred to the lower endof cylinder 92to raise the .discharger shoeyand when valve VLSV is energized or deenergized, respectively, the basket bottom valve similarly is lifted or lowered-by pressure in the upper or lower end of cylinder I34.

The timers indicated on-panel P2 are adjustable time relays or'time delay switchesof known construction.- They preferably are of the Multifiex type wherein several individually timed contacts are incorporated in a composite unit, although a much larger number of separate timer units'would also serve. A process timer having'five numbered contacts is indicated at PT; a control timer having three numbered-contacts is indicated at CT; and a discharge timer havingfour numbered contacts is indicated at Dr. The driving motors and clutches'of there-1 spective timers are-indicated inFig. 15: for ex-' ample, as PTM (process timer motor) and PTC (process timer clutch), respectively; and the re spective contacts of the timersare indicatedon the diagram by corresponding letters-andnum bers. Designations I. C., T. C.and T. O. .beside the several timer contacts in 'Figx15 indicate, respectively, that a contactis closed when-its timer is energized (instantaneously closed); or closed by action ofthe timer (timer closed), or opened by action of the timer (timeropened).

Aside fromrclay WR and the timers, the control 'panels P2 and P3 maycarry a brake control relay BR governing the circuittovalve BSV, control relays CR5, CR2, =CR3-and' CR4,- 'contactors L and H for energizing the low and high; speed windings of prime mover MM'through motor-contacts L and H, .contactol" DMS controlling the corresponding discharge motor contacts, and pro tective power failure and power loss relaysPFR and PLR, respectively. I Master switch MS-v (Fig. 16) governs the power supply for the driving systern; Energizing current for'the control elements is supplied by lines Li and L2 (Fig. 15);

It will be noted that discharger motor contacts DMS must be closed by energizing relay DMSin order to energize the discharge drive motor DM; also, that normally open contacts DMS3 of the same relay must be closed in order-to engage the discharge clutch DC through valve DCSV; and that relay DMS can be energized only through a series of contacts including a normallyopen contact of control relay CR land normally closed contacts of'main drive motor contactors H and-L. Therefore, in order for the discharge 'driveto become active, CR4 must first be "energized. This requires a circuit connection through the normallyclosed speed switch contact'ZSl, whichthe speed switch ZS holds open as long as the can trifugalbasket spins at speeds'unsafe'for discharger action, and which is closed only at a low basket speed, for example, one less than about 60 R. P. Accordingly, the discharge drive is kept inactive at all times except when the speed of basket 1 is low enough for safe operation of a mechanical discharger. In addition, the prime mover-"lulu must have been completely deenergized-by deenergizaticn cf contactors H-and L before the discharge drive can be rendered active through the normally closed contacts of H "and L. The organization of elements also" is devised so that the i-mechanical discharger itselfis held in'idle position and prevented fromoperating-at all timesexcept when the speed of the basket is not too -high fo1 safe discharger "action. As shown in Fig.- l5, solenoid valves DSV l and 'DSV! which control the motivators of discharger it are normally held deenergized by the normally open contact of relay CR5, and, since CPA stays deenergized as long as the speed switch ZSi is open, the discharger shoe 2% is held safely in its idle upward and inward position during all spinning periods of the machine. Closing of the CR4 contact is necessary for operation of the clischarger and can occur only through the closing of contact ZS! at a very low basket speed.

A complete sequence of operations will now be described:

A. The machine being at rest, switch MS is closed. If all phases are in proper relation, PER and PLR contacts close and CPA is energized.

B. The jog button J is pressed to bring the basket to a suitable loading speed, contactor L thus being energized to connect motor MM on its low speed winding. A charge of the material to be treated is admitted into basket I in the usual manner.

C. The run button R is then pressed to start the spinning period and the automatic phase of operations which divides itself into stages:

1. Relay GR! is energized, starting timers PT and CT and energizing contactor I. through contact CR! so that motor MM acts on its low speed winding to accelerate the basket. Meanwhile, the speed switch ZS has opened its contact 28% to deenergize relay CR4 during the spinning period.

2. After a predetermined interval determined by its setting, control timer contact CTE is closed by timer CT. This energizes relay CR2, deenergizes contactor L, energizes contactor H so that motor MM will continue accelerating to full speed on its high speed winding, and stops the control timer due to opening of contact L in the circuit to its motor CTM.

3. At a predetermined interval after the press ing of button R, as determ ned by the setting of process timer contact PTA, that contact closes to energize WWSV and start a first washing operation through sprayer I8. The first washing operation is terminated after a predetermined period by timer opening of contact P'I l.

4. After a further predetermined interval determined by the setting of process timer contact PTB, that contact closes to reenergize WWSV and thus start a second washing operation which is discontinued after a desired interval by timer opening of contact ZTfi.

'5. After a desired period of spinning determined by its setting, process timer contact PT2 opens to deenergize relay CR2, deenergize contactor H and re-energize contactor L, whereupon motor MM starts regenerative braking from full speed on its low speed winding. At the same time, control timer CT is restarted through contact L in its circuit.

5. After an interval of regenerative braking determined by the setting of control timer contact GT3, that contact closes, relay BB, is energized, and contacts of ER, energize BSV to apply the friction brake while opening the circuits to contactors L and H so that motor MM becomes completely inactive. The machine then continues its deceleration under the action of the friction brake.

7. As the speed of the decelerating machine approaches zero, the speed switch ZS closes contact ZS! to energize relay CR4 and start the discharge timer DT through a normally open CR4 contact. The discharge timer then takes over the control of operations attendant to dischargall) ing treated solids from the basket, and proceeds to actuate the several elements involved at de sired intervals determined by the settings of its respective contacts.

(a) First, contact DT2 closes, thus energizing the discharge motor contactor DMS which starts the discharge drive motor DM, opens contact DMS2 to deenergize relay BR. and release the friction brake, and closes contact DMSE to energize the discharge clutch solenoid valve DCSV and the valve lifter solenoid valve VLSV. l'he discharge clutch DC then engages to bring and hold the basket to its negative discharge speed, and valve lifter ll operates meanwhile to lift the basket bottom valve 52 to its raised position exposing basket outlet 4a.

(b) After a suitable interval, contact DTS closes to energize DSV I, thus applying into chamber of discharger housing 523 air pressure which causes the discharger shoe 2% to swing outward into the wall of solids in the reversely rotating basket.

(c) After a time interval suitable for digging a complete swath of solids from the top of that wall, contact DT4 closes to energize DSV2 which applies in the upper end of cylinder 32 air pressure that moves the discharger shoe downward in the basket. During this movement the remainder of the wall of solids is dug away from the basket side wall by rotation against the tip and face of the dropping shoe.

((2) After a suitable interval of downward shoe movement, contact DT3 opens to deenergize DSVl, whereupon pressure is released from discharger housing chamber 85 and spring acts to swing shoe 2B inward over the face of basket bottom ii.

(e) After a suitable interval of inward shoe movement, contact DT i opens to deenergize DSV2, whereupon pressure is shifted from the upper end to the lower end of cylinder 92 and the discharger shaft and shoe 2?; move upward. The shaft moves along the end of the ledge hi2 until the shoe has reached its uppermost or idle position, at which point spring 88 pulls the dis charger assembly farther inward so as to hold the shoe over the face of ledge H12.

(1) After a suitable interval of upward shoe movement, contact DT2 opens to deenergize contactor DMS, which in turn deenergizes the discharge motor DM and valves DCSV and VLSV while re-energizing relay BR. Accordingly, the discharge drive is inactivated both by disengaging its clutch and stopping its motor; pressure is shifted to the lower end of valve lifter cylinder 53 to lower the basket bottom valve; and the brake solenoid valve BSV is energized to apply the friction brake and stop the reverse rotation of the machine.

D. Finally, the reset button RS is pressed, in order to open all the control circuits so that relay CR! is deenergized, timers PT, CT and DT reset, and the friction brake is released. The machine then is ready to start on another cycle.

It is to be understood that the detailed description and the accompanying drawings are illustrative and that the improvements herein disclosed may be embodied in various forms of construction within the scope of the appended claims. In place of the particular types of driving elements, braking elements, control elements, etc., here illustrated other types may be employed in the arrangements and modes of operation claimed, as will be apparent to those skilled in the art.

I claim:

1. In a heavy cyclical centrifugal machine, the combination comprising a solids-retainingbasket carried on a driving shaft, a mechanical solids discharger having an elongated shoe swingable inside the basket so as to move the shoe tip out to and in from the basket side wall, a rotary prime mover operative upon said shaft in one direction for bringing the basket to a high centrifuging speed, another rotary driving means operative upon the shaft at a low speed in the opposite direction for bringing and holding the basket to slow reverse rotation suitable for operation of said mechanical solids discharger, said shoe extending in said one direction so that it cannot dig into solids, rotating within the basket in that direction, and means rotated with said shaft and responsive to deceleration of its speed following each operating period of said prime mover to actuate said other driving means.

2. In a heavy cyclical centrifugal machine, the combination comprising a solids-retaining basket carried on a driving shaft, a solids discharger having an elongated shoe swingable horizontally inside the basket so as to move the shoe tip out to and in from the basket side Wall, a rotary prime mover operative upon said shaft in one direction for bringing the basket to a high centrifuging speed, and rotary driving means operative upon the shaft at a low speed in the opposite direction for bringing and holding the basket to slow reverse rotation suitable for operation of said discharger, said shoe extending in said one direction so that it cannot dig into solids rotating with the basket in that direction.

3. In a heavy cyclical centrifugal machine, the

combination comprising a solids-retaining basket carried on a rotary driving shaft, a rotary prime mover operative upon said shaft in one direction for rotating the basket to a high centrifuging speed, braking means for decelerating the basket from high speed, rotary slip driving means operative upon said shaft in the opposite direction at a constant low speed suitable for operation of a mechanical solids discharger in the basket,-

and. control means including a device rotated with and responsive to the speed of said shaft and acting at a predetermined speed in each period of deceleration of the basket from said centrifuging speed to inactivate said braking means and activate said low speed driving means.

4. The combination of claim 3, said control means including timing means started by said device and brake and low speed drive control elements actuated by said timing means.

5. In a heavy cyclical centrifugal machine, the combination comprising a solids-retaining basket carried on a vertical driving shaft, a solids. discharger having a shoe movable within the basket out to and in from the basket side wall and down and up along said wall and having motivators to produce the respective shoe movements, activators forsaid motivators, a rotary prime mover operative upon said shaft in one direction for rotating the basketv to a high centrifuging speed, braking means for decelerating the basket from high speed, another rotary driving means operative upon said shaft in the opposite direction at a constant low speed suitable for operation of said discharger, actuators for the respective driving means, and control means including a device responsive'to the speed of the decelerating basket for moving said actuators to inactivate said braking means and activate said low speed driving means as the speed of the decelerating basket approaches zero, said controlmeans including timing meansactivated by saiddevice and a plurality of elements actingsuecessively through respective connections with the said actuators to cause in succession outward, downward, inwardand upward movements of said discharger shoe followed by inactivation of said low speed driving means and reactivation of said braking means to stop the rotation of the basket in said opposite direction.

6. A combination as described in claim 5 wherein said basket has a bottom outlet for dis charged solids, and comprising a vertical mov able valve fitting said outlet, power operated means movable to lift and lower said valvaand actuating means connected with said power oper ated. means, the aforesaid control means includ ing elements interconnecting saidtiming means and said actuating means for morvingthe latter to, lift said valve andto lower it, respectively, when said low speed driving means is activated and inactivated.

7. In a heavy cyclical centrifugal machine,

the combination comprising a solids-retaining basket carried on a driving shaft, a rotary slip driving means operative uponsaid shaft for rotating the basket to a high centrifuging speed, a discharger movable within the basket to dig out solids rotating with it at low speed, another rotary slip drivingmeans operative upon said shaft at a constant low speed suitable for operation of said discharger and adapted to bring and hold the basket tosaid low speed, actuators for the respective driving means, and control means.

having an elongated shoe movable horizontally within the basket to dig out solids rotating with .it at a suitable low speed, a rotary driving motor having its shaft connected with the basket shaft for rotating it to a. high centrifuging speed, the motor shaft having an extension away from the basketshaft, a friction drum fixed to said extension to rotate with it and the basket at all times,

a driving wheel carrying rotary friction elements movable radially relative thereto to engage and disengage said drum, said elements being normally disengaged from said drum, driving means connected with said Wheel for rotating it and said friction elements at low-speed, and means operative after each period of action of said motor for moving said friction elements into slippable engagement with said drum under predetermined pressure to bring and hold the motor and basket shafts to said low speed.

9. Apparatus as described in claim 8, said driving means including speed reduction gearing and a constant speed drive for the same.

10. In a heavy cyclically operated centrifugal machine having a solids-retaining basket. suspended on a vertical shaft and a discharger having anelongated shoe movable horizontally within the basket to dig out solids rotating with it at a suitable lowspeed, a rotary driving motor I having its shaft connected with the basket shaft for rotating it in one direction to a high centrifuging speed; said shoe extending in said one direction so that it'cannot dig into solids rotating with the basket at high speed, the motor shaft having an extension away from the basket shaft, a friction drum fixed to said extension to rotate with;it and the basket at all times, a driving wheel carrying rotary friction elements movable radially relative thereto to engage and disengage said drum, said elements normally being disengaged from said drumtdriving means connected withsaid wheel for rotating it and said frictionelements at said low speed in the direction. opposite to thehigh speed rotation, and. means operative after each'period of action of said motor for moving said friction elements into slippable engagement with said drum under predetermined pressure to bring and hold .the motor and basket shafts to, said low speed in saidoopposit'e direction o 11..In a heavy. cyclical centrifugal machine having a solids-retaining basket carried on a driving shaft and a power-operated discharger for digging from the basket solids rotating thereinat a low speed, control means connected with the discharger including a motivator normally positioned to hold it inoperative but movable to another position to render the discharger operative; a switch element connectedwith said motivator and movable toiposition the latter, and a switching device having/parts rotated with and'responsive to the speed of rotation of saidshaftfor positioningsaid switch element, said device being operative to move said element and thus'shift said motivator to said other position when" said shaft is decelerated into a predetermined low' speed range in which said discharger may beoperated safely, and to move said switch element so as to return said motivator to its normalposition and thus keep the discharger inoperative when said shaft is accelerated to a speed 'above said range. v

12. In a heavy cyclical centrifugal machine, the combination comprising a solids retaining basket carried on a driving shaft, rotary slip driving means ,includinga prime mover operative upon said shaft at a high speed for bringing the basket tocentrifuging speed, means for decelerating the basket from centrifuging speed, another rotary slip driving meansv operative upon saideshaft at a substantially constant low speed suitable for discharging solids from the basket, so as to bring and hold the shaft and basket to such discharging speed, and control means connected with said other slip driving means including aimotivator' normally positioned to hold the same inoperative but shiftable to anotherposition to render the same operative, a switch element connected with said motivator and movable to position the latter, and a switching device having parts rotated with and responsive to the speed -of rotation of said shaft for positioning. saidswitch element, said device beingioperative to movesaid element and thus-shiftgsaid motivator to said otherlposition when said shaft is decelerated into a predetermined low speed rangelin which said discharger may be operated safely, and to move said switch element so as to return said motivator to its normal position and thus hold the discharger inoperative when said shaft is accelerated to a speed above saidrange.

13. In a heavy cyclical centrifugal machine having a vertical spindle, a solids-retaining basket carried'on the spindle and a discharger including a shoe movable horizontally within the basket to dig out solids rotating with it at asuitable low speed, a rotary drivingmeans having a shaft connected waas'aia spindlefor rotating the basket to a high centrifuging speed, a stub shaftbeyond the confines of said motor and connected for rotation with said motor shaft, a friction drum fixed to said stub shaft to rotate with it and. with the basket at all times, a driving wheel carrying friction elements movable radially relative thereto to engage and disengage said drum, said elements normally being disengaged from said drum, driving means connected with said wheel for rotating it and said friction elements at a substantially constant speed, and means operative after each period of action of said driving motor for moving said friction elements into slippable engagement with said drum under predetermined pressure to bring and hold the basket to a low speed suitable for operation of the discharger.

14. In a heavy cyclical centrifugal machine having a vertical spindle, asolids-retaining basket carried on the spindle and a discharger including a shoe movable horizontally within the basket to dig out solids rotating with it at a suitable low speed, a rotary driving means having a shaft connected with said spindle for rotating the basket to a high centrifuging-speed, a stub shaft beyond the confines of said motor and connected for rotation with said motor shaft, a friction drum fixed to said stub shaft to rotate with it and the basket at all times, a driving wheel carrying friction elements movable radially relative thereto to engage and disengage said drum, there being radially extensible and retractable fluid pressure responsive means between said wheel and said elements formoving said elements and normally holding the same disengaged from the wheel, a stubshaft carrying said. wheel, a driven gear fixed to said wheel shaft, a driving gear in mesh with said griven gear, means for driving said driving gear at a substantially constant speed so as to rotate said Wheel and the friction elements at a corresponding speed, and means for applying fluid pressure to said pressure responsive means so as to engage said friction elements with said drum under a predetermined. pressure and thereby bring and hold the basket to a low speed suitable for operation of the dis charger.

15. For a heavy cyclical centrifugal machine having a solids-retaining basket carried on a ver-' tical spindle, a discharger including a shoe mov-* able horizontally within the basket to dig out solids rotating with it at a suitable low speed and rotary driving means including a driving shaft connected with said spindle for rotating the basket to a high centrifuging speed, a low speed driving mechanism for bringing and holding the basket to discharging speed, comprising a friction drum adapted .to rotate on a fixed axis and to be connected for rotation with said driving shaft, a driving wheel carrying friction elements movable radially relative thereto to engage and disengage said drum, there being radially extensible and retractable fluid pressure responsive means between said wheel and said elements for moving said elements and normally holding the same disengaged from the wheel, a stub shaft carrying said wheel, a driven gear fixed to said wheel shaft, a driving gear in mesh with said driven gear, means for driving said driving gear at a substantially constant speed so as to rotate said wheel and theifriction elements at a corresponding speed, and means for applying fluid pressure to said pressure responsive means so as to engage said friction elements with said drum under a predetermined pressure and thereby bring and hold the basket to a low speed suitable for operation of the discharger.

JOSEPH HERTRICH.

Number Name Date Carroll June 28, 1927 Number 22 Name Date Pecker Oct. 6, 1936 Steps Jan. 11, 1938 Tholl Mar. 29, 19-38 Olcott Feb. 15, 1949 Tholl Oct. 11, 1949 Tholl Feb. 21, 1950 Fields Jan. 22, 1952

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