US2828020A - Safety device for centrifugal machines - Google Patents

Description

March 25, 1958 R. J. HUSER EIAL 2,828,020

SAFETY DEVICE FOR CENTRIF'UGAL MACHINES Filed April ,9, 1954 2 Sheets-Sheet 1 INVENTOR Elk/(arr! J. Hvser Car/JSCfiU/ze s i i a ATTORNEYS March 25, 1958 R. J. HUSER ET AL 2,828,020

SAFETY DEVICE FOR CENTRIFUGAL MACHINES I 2 Sheets-Sheet 2 Filed April 9, 1954 ATTORNEYS Ilnited States 2,828,020 A z SAFETY DEVICE FOR CENTRIFUGAL MACHINE Richard J. Huser, MountHealthy, 'andfCarl J. Schulzc, Hamilton, Ohio, assignors to The Western states Machine Company, Hamilton, Ohio, a corporation of Utah 'Application April '9, 1954, Serial No. 422,151

6 Claims. or. 210-375 processes such as, for example, the manufacture, refiningj or drying of sugar, dextrose or other suitable crystalline or granular solids.

Centrifugal machines of the type referred to above gen-. erally include a basket bottom valve 'which is selectively moved between a closed position, in which it "covers a solids outlet in the bottom of the centrifugal. basket, and f an open position, in which the valve exposes that outlet,

andla discharger which, after the treated solids have been deposited as a more or. less hard wall within the basket} operates to remove the treated solids from the basket for discharge through the basket bottom outlet. It is apparentthat operation of the discharger at a time when the basket bottom outlet is either fully or partially covered by the basket bottom valve creates a hazardous and otherwise objectionable condition in that the removed solids pileup against the valve and discharge'of the solids from the basket is faulty and incomplete.

atent 1 Accordingly, it isan important object of the lnvention to provide a safety device for centrifugal machines of the described character which prevents operation of the discharger until the basket bottom valve has attained its open position and which then prevents closing of the basket bottom valve during operation of the discharger;

Centrifugalmachines of the heavy-duty cyclical type remove the deposited solids from'the wall of the basket by' a discharger shoe which, during operation of the discharger, moves radially outward from an inoperative position spaced from the wall of treated solids to cut into and remove the upper portion of the chargeor wall of solids as the basket is slowly rotated. When the shoe reaches a position at or near the side wall of the basket,

the radially outward movement of the shoe is discontinued and the shoe is then moved axially within the basket to complete removal of the wall of treated solids,

whereupon thedischarger shoe is returned by suitable I radially inward and axial movement to its inoperative position. Further, in certain centrifugal machines of the described character the basket bottom opening which forms an outlet for discharged solids is provided with a vertically"movable valve of substantially conical configuration which, when it is raised and tilted in relation to the'basket, uncovers the outlet and avoids interference 5 with, the operation of the discharger or the rotation or discharging of solids in the basket.

According to a feature of the present'invention, a pentri-fugal machine of'the heavy-duty cyclical-'type'having' a discharger and a basket bottom valve of the kind referred to above'is provided with a safety device which interlocks the discharger shoe'and valve actuating mechanisms so that radially outward movementof the shoe "into the Wall of treated solids cannotoccur until :thevalve I has been liftedtouncover the basket bottomopening or 2,828,020 Patented Mar. '25, 1958 starting of high-speed rotation of the latter until the dis- 1 charger.shoe has been returned to its inoperative position radially remote from the basket wall and the basket bot? tom valve has been returned to its closed position there'- by to avoid the hazards resulting from high speed rotation and loading of the basket at a time when the discharger shoe is disposed adjacent the basket wall and capable of contacting the solids building-up on that wall or the basket bottom valve is still in its open position to permit outpouring of the new charge through the basket bottom opening.

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

in the drawings: T

Fig. l is a sideelevational view of the basket, dis'-" charger and basket bottom valve assembly of a centrif- Fig. 2 is a fragmentary top plan view of the centrifugal machine of Fig. 1, again with some parts being broken away' and with some being shown in horizontal crosssection; I

Fig. 3 'is a fragmentary top plan view of a portion of Fig. 2, but on an enlarged scale, the discharger shoe and safety device being shown in full lines in the respective positions occupied thereby during high-speed rotation of the'basket, while the broken-line representations of the discharger shoe and safety device show their positions during the discharging of the treated solids; and

'Fig. 4 is a vertical sectional view taken along the linev 4--4 of Fig. l, the basket bottom valve and associated actuating mechanism being shown in full lines in their valve closed positions, while the broken-line representa tions of these parts illustrate the positions occupied thereby when the valve is opened.

.Referring to the drawings in detail, the present in- V vention is there illustrated, merely by way of example,

as applied to a heavy cyclical centrifugal machine of the includes a large centrifugal basket 1 having a perforated side wall 2, cap 3, and bottom 4 and which is carried by the lower end of a vertical driving shaft or spindle 5. The spindle 5 is rotatably mounted in snitable'bear ings (not shown) and is driven by an electric motor assembly (not shown) capable of effecting high speed rotation or spinning of spindle 5 in one direction for 5 centrifugally separating the liquid and solid constituents of the charge in basket 1, and of effecting relativelylow 1 speed rotation in the opposite direction'during discharging of the treated solids. I

After each spinning period, the treated solids which 1 form a more or less hard'wall against the basket side" wall are removed by the action of a mechanical discharger. Basket bottom 4 has a central opening 4a disposed around spindle and forming a solids outlet, while basket cap 3 has a central opening 3a affording access to the interior of the basket. The entire basket is surrounded by a stationary curb 6 which collects the liquid expelled during each spinning period and has a centrally open top 7 providing support for a discharger 8 and a valve lifting device 9 which actuates a frusto-conical valve 10 fitting the outlet 4a and surrounding spindle 5 for movement vertically to expose the outlet during each discharging operation.

The principal element of the dischargcr 8 is a shoe 11 carried on a vertical shaft 12 and moveable inside the basket both vertically, so that its tip or working end can traverse the axial length of the basket between cap 3 and bottom 4, and horizontally, so that the tip of the shoe can. move radially in and out relative to basket side wall 2.

The operating mechanism of discharger 8 of the illustrated centrifugal machine centers about a supporting stud 13 (Fig. 2) which projects upwardly from a base plate or flange 13a secured to the curb top 7. A bracket or housing 14 is mounted on stud 13 to swing horizontally about the axis of the latter, and extends from the stud toward spindle 5 to a vertical guide portion 14a which overhangs the inner edges 7a and 3a respectively, of curb top 7 and basket cap 3 and slidably receives the upper end portion of discharger shaft 12. Shaft 12 and its hearings in the guide portion of housing 14 are formed so that, the discharger shoe 11 cannot swing with respect to vthe housing 14, although it can swing with the housing onstud 13 and is also free to be moved axially up and down in its guide passage in the housing.

The swinging, movements of housing 14 and shaft 12 about stud 13 can dispose shoe 11 at the broken line position or the full line position of Fig. 2 or at any intermediate position, for example, as shown in broken lines on Fig. 3. As more fully described in the above identified patent, these swinging movements are brought about and limited to the desired extent by two slidable abutment members 15 and 16 projecting laterally from opposite sides of housing 14 and having their ends arranged to abut against flat faces of fixed posts 17 and 18, respectively, which extend from the base plate or flange supporting stud 13, Abutment member 15 is slidably extended from the relatedside of housing 14 by the action of fluid pressure admitted to a related chamber (not shown) of the housing and, in bearing against fixed post 17, eifects swinging of the housing and the discharger shaft counterclockwise about stud 13 (Fig. 2). Such swinging of the housing 14 and shaft 12 causes shoe 11 to move radially outward from; its full line position (Fig. 2) toward its broken line position. However, before the shoe tip reaches basket side wall 2, abutment member 16 engages against fixed post 18 and provides a retarding or dashpot eifect at the conclusion of the radially outward movement of the shoe.

On the other hand, when the fluid pressure acting against abutment member 15 is released, that abutment member is free to slide inward with respect to housing 14, and the discharger shoe swings radially inward from the basket sidewall under the combined action of a spring (not shown) disposed within housing 14 and acting out- Wardly against abutment member 16, and the pull of a heavy tension spring 19 which has one end fixed to an anchor on the base plate and has its other end fixed to a suitable eye extending from the free end of housing 14. The spring within housing 14 corresponds to the spring 80 within housing 72 as shown in Figs. 5 and 8 of the drawings of U. S. PatentNo. 2,667,974.

The up and down movements of the discharger shoe are brought about entirely by the action of an air cylinder 20 which is carried in vertical position alongside shaft 12 by suitable brackets on the housing 14. Cylinder 20 has a plunger 21 3) extending downward to a detachablecoupling (not shown) with the body of the discharger 4 shoe 11. The length of cylinder 20, that is, the stroke of plunger 21 in it, is fixed so that when the plunger lies at the upper limit of its movement, the discharger shoe 11 is held just below the basket cap 3, as shown in Fig. 1, while at the lower limit of plunger movement the shoe lies just above the basket bottom 4.

As seen in Fig. 1, the base plate for the discharger has a portion which overhangs the inner edge of curb top 7 and to which a bracket 22 is fixed so as to extend downward into the basket. At its lower end, bracket 22 forms a horizontal ledge directed toward the discharger shaft 12, and this ledge is located just below the bottom of shoe 11 when the shoe is in its raised position. Accordingly, when the shoe is down, and the discharger is swung radially inward by spring 19, the side of shaft 12 abuts slidably against the edge of the ledge on bracket 22. Cylinder 20 then eifects movement of shaft 12 upward along the ledge until shoe 11 has reached its upper position, whereupon a final inward swinging occurs to place the base of the shoe over the face of the ledge on bracket 22. That is the idle position of the discharger from which it cannot fall toward the bottom of the basket even though the pressure in cylinder 20 be released. The overhanging portion 13b and bracket 22 of the illustrated embodiment corresponds to parts 100 and 101, respectively, shown in Figs. 3 and 4 of the drawings of U. S. Patent No. 2,667,974. The housing 14 and parts connected with it correspond to the housing 72 and its connected parts as shown in Figs. 3 to 8 of the drawings of said patent.

When the discharger is to be operated, the basket drive is adjusted to bring the basket to its low negative speed and the basket bottom valve is lifted to expose solids outlet 4a. Pressure fluid is then admitted into housing 14 so that abutment member 15 acts, in the manner hereinbefore described, to slowly swing the tip of shoe 11 outward into material in the basket, and this outward swinging movement continues as the material is rotated against the shoe until the latter reaches the basket side wall. Meanwhile, the shoe has moved clear of the ledge on bracket 22 and, having dug a complete swath from the top of the wall of solids, the shoe now is ready to move downward and dig out the remainder of that wall. Such downward movement is accomplished by admitting pressure into the upper end of cylinder 20 and, at the limit of the downward movement, the fluid pressure acting in housing 14 is released so that shoe 11 swings radially inward under spring force to assume the position limited by abutment of shaft 12 against the ledge on bracket 22. Finally, pressure is shifted from the upper end to the lower end of cylinder 23 to raise the shoe to its idle position over the ledge of bracket 22. All these operations may be brought about in the manner shown and described wit respect to housing 72, shaft 21, shoe 22, cylinder 92 and ledge 102 in the drawings and specification of said patent No. 2,667,974.

Lifting and lowering of the basket bottom valve 10 are accomplished through the valve lifting device 9 which includes a lifting arm 23 mounted for swinging about a horizontal pivot pin 24 and having a laterally offset protruding end 25 engageable in an annular recess 26 defined by a downwardly curved flange at the top of the valve 10. Arm 23 normally hangs vertically, as shown in full lines on Fig. 4, from the pivot pin 24 which, in turn, is carried by a lug 27 integral with a supporting tube 28 depending into the basket from a suitable mounting plate secured to the curb top 7. Pivot pin 24 is offset laterally and downwardly-from the lower open end of tube 28, and lifting arm 23 is bifurcated attheend opposite to the protruding end 25 to provide parallel, spaced apart legs 29 (Fig. 3) which extend backward from pin 24 at opposite sides of lug 27 and at an angle to arm 23 so as to terminate at a point below the lower open end of tube 28. At that point, a pin 30 pivotally joins legs 29v to the lower end of a connecting rod 31, shown in broken lines in Fig. i,

which extends vertically in tube 28 to a pivotal connection with the plunger of an air cylinder 32 mounted vertically upon curb top 7.

Suitable air lines (not shown) lead into the upper and lower ends of air cylinder 32 to supply air under pressure to the related ends of the cylinder and thereby to effect lowering and raising of the cylinder plunger. When air under pressure is admitted to the upper end of cylinder 32, the plunger and connecting rod 31 move downward and thrust the lifting arm 23 from its idle position, shown in full lines in Fig. 4, to its working position, shown in broken lines in Fig. 4. As the arm 23 moves into its working position, its protruding end 25 engages in recess 26 and lifts the frusto-conical valve to a tilted-raised position exposing the basket bottom outlet 4a as indicated in broken lines in Fig. 4.

When the pressure is shifted from the upper end to the lower end of cylinder 32, arm 23 is drawn back to its idle position where it hangs below a portion of the curb top, and the conical valve 10 is guided by spindle 5 back to its closed position over solids outlet 40. When the valve is in its closed position, the arm 23 of the valve lifter 9 hangs free of the bottom valve, enabling the latter to be moved freely by hand if desired. The arm 23 is also away from the orbit of material in the centrifugal basket and from the path of charge material entering the basket during a loading operation.

The supplying of pressure fluid to housing 14 and cylinder 20 of discharger 8, and to cylinder 32 of valve lifting device 9 is normally controlled so that the discharger shoe 11 is moved radially outward into the wall of solids in basket 1 only after valve 10 has been lifted to its open position, the valve 10 not being returned to its closed position over solids outlet 4a until the discharger shoe has been returned to its radially inward, idle or rest position. Malfunctioning of the controls, however, may disturb this necessary sequence of the operating cycles of the discharger and the valve lifting device. It is apparent that operation of the discharger at a time when the solids outlet 4a is either fully or partially covered by the basket bottom valve 10 creates a hazardous and otherwise objectionable condition in that the removed solids pile up against the valve, which of course results in a faulty and incomplete discharge of the solids from the basket.

In accordance with the present invention, a safety device is provided to prevent the radially outward movement of the discharger shoe 11 until the valve 10 has been raised and tilted to its fully open position, and then to prevent the return of the valve to its closed position until the discharger shoe has been restored to its restor idle position. The illustrated safety device, which is generally identified by the reference numeral 33, per forms the above stated functions by interlocking the swinging movements of discharger housing 14 and the vertical movements of connecting rod 31 of the valve lifting device. That is, safety device 33 operates to prevent swinging of housing 14 in the direction moving discharger shoe 11 into the wall of solids within basket 1 until connecting rod 31 has been moved downwardly for effecting raising and tilting of valve 10, and then to prevent upward movement of connecting rod 31, for returning valve 10 to its closed position, until discharger housing 14 has been swung in the direction carrying discharger shoe radially inward away from basket side wall 2.

In order to operate in the manner described above, safety device 33 includes a vertical rod 34 extending slidably through a suitable bearing 35 which is carried by curb top 7. Rod 34 is disposed adjacent to supporting tube 28 of valve lifting device 9 and, at its lower end, is adjustably secured to a coupling 36 which is pivotally mounted on pin 30 connecting legs 29 of the lifting arm to rod 31. Thus, when arm 23 is in its idle position, shown in full lines on Fig. 4, the upper end of rod 34 extends a relatively great distance above the curb top.

Q or abutment member 37 (Fig. 3)

However, as arm 23 swings into engagement with valve 10 and raises and tilts the latter, rod 34 is drawn downwardly so that the upper end thereof then projects only a relatively short distance above bearing 35 on the curb top. It is therefore to be seen that the vertical positioning of the upper end of rod 34 is correlated with the position of arm 23 and valve 10.

Safety device 33 further includes a sector-shaped plate which is swingably mounted upon a vertical pivot 38 adjacent rod 34 to move in a horizontal plane immediately above bearing 35. Abutment member 37 is swingable between a first position, shown in full lines on Fig. 3, wherein the edge 39 of the abutment member is alongside the path of travel of rod 34, and a second position, shown in broken lines of Fig. 3, wherein the abutment member 37 overlies bearing 35 and projects across the path of travel of rod 34. The swinging movements of abutmentmember 37 are correlated with, or made responsive to, the swinging movements of discharger housing 14, and for this purpose, safety device 33 includes a link 40 having longitudinally adjustable couplings 41 and 42 at its opposite ends. The coupling 41 is pivotally connected, as at 43, to a point on the abutment member 37 spaced from the swinging axis of the latter. The coupling 42 is pivotally connected, as at 44, to a bracket 45 which is secured, as by bolts 46, to the base or mounting flange of cylinder 20 on discharger-housing 14. The various parts are ing 14 is disposed to position shoe 11 radially inward with respect to basket sidewall 2, abutment member 37 is disposed, as shown in full lines on Fig. 3, out of the path of travel of rod 34. However, as discharger housing 14 swings in the direction moving shoe-11 radially outward-toward the basket sidewall, the distance between the axis of the pivotal connection 44 and the swinging axis of abutment member 37 is progressively reduced, and the link 40 translates this reduction in distance to swinging of the abutment member 37 in the clockwise direction, as viewed in Fig. 3, to the position shown in broken line wherein the abutment member overlies bearing 35 and projects across the path of travel of rod 34.

From the foregoing, it is apparent that, when valve 10 is in its closed position and discharger shoe 11 is in its rest or idle position upon the ledge of bracket 22 (for example, during the spinning period of the cyclical, heavy-duty centrifugal machine), the upper end of rod 34 extends above the horizontal plane of swinging of abutment member 37 with the edge 39 of the latter bearing against the side of rod 34 which thereby prevents swinging of member 37 in the direction corresponding to radially outward movement of shoe 11 toward the basket sidewall. Thus, so long as valve 10 is in its closed position, the cooperative engagement of abutment member 37 with rod 34 prevents radially outward movement of the discharger shoe into the wall of solids within basket 1. However, when valve 10 is raised and tilted to its open position, rod 34 is lowered to a position in which its upper end lies below the horizontal swinging plane of abutment member 37 thereby to permit swinging of the latter to the broken line position of Fig. 3 in response to swinging of housing 14 in the direction moving shoe 11 radially outward into the wall of solids within the basket. So long as discharger shoe 11 is disposed adjacent the basket sidewall to remove solids from the latter, abutment member 37 overlies bearing 35 and extends across the path of travel of rod 34 thereby to prevent upward movement of the rod and to block the return of valve lifter arm 23 to its idle posititin, shown in full lines on Fig. 4. Thus, the valve 10 cannot be returned to its closed position covering solids outlet 4a while the discharger shoe is operative to remove solids from the basket sidewall. When discharger shoe 11 is moved radially inward at the conclusion of the discharging operation, the corresponding arranged and dimensioned so that, when housswinging of discharger housing 14 causing swinging of abutment member 37 in the counterclockwise direction, as viewed in Fig. 3, to remove the abutment member from the path of travel of rod 34 so that the latter may then be raised in response to return of arm 23 to its idle position for disposing valve over solids outlet 4a. Preferably, edge 39 of abutment member 37 is not completely removed from the path of travel of rod 34 until shoe 11 has undergone its final increment of radially 'inward movement for disposing the shoe upon the ledge of bracket 22. From the foregoing, it can be seen that safety device 33 ensures the proper sequence of operation of discharger 8 and of valve lifting device 9.

In accordance with the present invention, safety device 33 is further adapted to prevent loading of basket land high speed rotation or spinning of the basket so long as the discharger 8 is in operation or the valve 10 is in its open position. For this purpose, a conventional limit switch 47 (Figs. 1, 2 and 4) is suitably mounted upon cylinder 32 of valve lifting device 9. Limit switch 47 is interposed in the electrical circuits (not shown) controlling the loading of a charge into the basket and the high speed of rotation of the basket so that opening of the contacts of switch 47 prevents loading of the basket and high speed spinning or rotation of the latter. For example, it may be placed in the circuit to a control relay such as indicated at CR1 in an electrical control system of the type illustrated in Fig. and described in the specification of said Patent No. 2,667,974. Safety device 33 is arranged to actuate limit switch 47 so that the contacts of the latter are open whenever the parts of the safety device occupy the positions thereof corresponding to operation of the discharger and opening of valve 10.

In the embodiment of the invention illustrated in the drawings, switch 47 includes an actuating lever48 extending rockably from the switch housing and having a roller 49 at its free end (Fig. 4) disposed above and in the path of travel of rod 34. Actuating lever 48 is spring urged downwardly to a position wherein the switch con-' tacts are open, and rod 34, when raised in response to return of arm 23 to idle position with closing of valve 10, bears at its upper end against roller 49 to rock lever 48 upwardly for closing of the switch contacts. Thus, the switch contacts of limit switch 47 are closed so long as valve 14) is in its closed position covering the solids outlet 4a thereby to permit loading of the basket and high speed rotation or spinning of the latter.

The rod 34 being raised when valve 10 is in its closed position, any movement of discharger shoe 11 radially r outward toward the basket side wall is then prevented by engagement of abutment member 37 against raised rod 34; so the operation of the discharger cannot occur when the machine is in a condition permitting it to be loaded or rotated at high speed. However, when rod 34 is lowered in response to opening of basket bottom valve 10 thereby to permit swinging of abutment member 37 and operation of the discharger, the upper end of rod 34 moves downwardly away from roller 49 on switch actuating lever 48 to permit downward swinging of the latter for opening of the contacts of the limit switch. Thus, when valve 10 is open and during operation of the discharger 8, the open contacts of switch 47 prevent energization of the electrical circuits controlling loading of the basket and high speed rotation or spinning ef'the latter.

Although safety device 33 has been described particular reference to a cyclical, heavy-duty centrifugal machine of the kind disclosed in U. S. Letters Patent No. 2,667,974, issued February 2, 1954, to Joseph Hertrich, it is to be understood that the described safety device may be employed in connection with any other centrifugal machines wherein the discharger shoe engages in similar radial and axial movements during the discharg operation, and opening and closing of the basket bottom valve isetfected by a device from which the necessary vertical movements of rod 34 can be obtained.

Further, it is to be understood that the detailed description and the accompanying drawings showing a particular safety device embodying the invention are merely illustrative and that the improvements herein disclosed may be embodied in various forms of construction within the scope of the appended claims.

What is claimed is:

1. In a centrifugal machine having a rotated basket provided with a solids outlet in the bottom thereof, a valve normally seated in a position covering the solids outlet, valve actuating means operative to raise the valve from said seated position for exposing the solids outlet and to lower the valve to said seated position, a discharger assern ly including a shoe having a rest position spaced inwardly from the basket side wall and movable away from that position radially and axially within the basket for removing treated solids from the latter through the solids outlet and discharger operating means for moving the shoe radially outward to the basket side wall, for moving .it axially along the latter and for returning the shoe .to said rest position, and mechanical interlock means including a first means positioned by said discharger operating means according to the horizontal position of said shoe, and a second means positioned by said valve actuating means according to the position of said valve, said second means including an element blocking movement, of said first means so as to prevent movement of saidshoe away from its rest position except when said valve is in a raised position, and said first means including an element blocking movement of said second means so as to prevent movement of said valve to its seated position except when said shoe is in its rest position.

2. In a centrifugal machine having a rotated basket provided with a solids outlet in the bottom thereof, a valve normally seated in a position covering the solids outlet, .valve actuating means operative to raise the valve from said seated position for exposing the solids outlet and to lower the valve to .said seated position, driving means for rotating said basket at high speed, a discharger assembly including a shoe having a rest position spaced inwardly from the basket side wall and movable away from that position radially and axially within the basket for removing treated solids from the latter through the solids outlet and discharger operating means for moving the shoe radially outward to the basket side wall, for moving it axially along the latter and for returning the shoe to said rest position, mechanical interlock means including a first means positioned by said discharger operating means according to the horizontal positon of said shoe, and a second means positioned by said valve actuating means according to the position of said valve, said second means including an element blocking movement of said first means so as to prevent movement of said shoe away from its rest position except when said valve is in a raised position, and said first means including an element blocking movement of said second means so as to prevent movement of said valve to its seated position except when said shoe is in its rest position, and means operative when said valve is away from said seated position to prevent the operation of said driving means.

3. In a centrifugal machine having a rotated basket provided with a solids outlet in the bottom thereof, a valve normally seated in a position covering the solids outlet, valve actuating means operative to raise the valve from. said seated position for exposing the solids outlet and to lower theyvalve to said seated position, a dis charg er assembly including a shoe having a rest position spaced inwardly from the basket side wall and movable away from that position radially and axially within the basket for removing treated solids from the latter through the solids outlet and discharger operating means for moving the shoe radially outward to the basket side wall, for

moving it axially along the latter and for returning. the

shoe to said rest position, and mechanical interlock means including a first member connected to said valve actuating means and movable bythe latter between first and second positions corresponding respectively to closing of the solids outlet by the valve and to exposing of the solids outlet by the valve, a second member connected to said discharger operating means and movable by the latter between first and second positions corresponding respectively to radially inward disposition of the discharger shoe remote from the basket side wall and to radially outward disposition of the discharger shoe adjacent the basket side wall, said first member, when in its first position blocking movement of said second member to its. second position, and said second member, when in its second position blocking movement of said first member to its first position, whereby said in-.

terlock means prevents operation of the discharger when the solids outlet is closed by the valve and then prevents closing of the solids outlet by the valve during operation of the discharger.

4. In a centrifugal machine; the combination according to claim 3, further comprising a switch adaptedto be interposed 'incircuits controlling loading and spinning of the basket so that such loading and spinning is possible only when said switch is closed, said switch being biased to its open condition, and a switch actuating member extending into the path of travel of said first member and engaged by the latter when said first member 'is in said position thereof corresponding to closing of the solids outlet to close said switch for then permitting loading and spinning of the basket.

5. In a centrifugal machine having a rotated basket provided with a solids outlet in the bottom thereof; the combination of a discharger assembly including a dis charger shoe, means supporting said shoe for radial movement outwardly toward the side wall of the basket and inwardly away from the basket side wall and for axial movement within the basket, pressure fluid operated means for successively moving said shoe from a rest position spaced inwardly from the basket side wall radially outwardto the basket side wall adjacent the top of the latter and axially down the basket side wall to remove the treated solids from the latter for discharge through the solids outlet, and then radially inward and axially up to return the shoe to said rest position, a valve normally seated in a position covering the solids outlet, pressure fluid operated valve actuating means for raising said valve to expose the solids outlet and for lowering the valve to its position covering the solids outlet, a vertically movable rod, means connecting said rod to said valve actuating means so that said rod is moved upwardly and downwardly in response to lowering and raising, respectively, of said valve, an abutment member, means mounting said abutment for swinging in a horizontal plane at level between the upper and lower limits of the travel of the upper end of said rod, and means connecting said abutment member to said means supporting the shoe so that when the shoe is moved radially outward to the basket side wall, said abutment member is interposed in the path of travel of said rod to prevent upward movement of the latter and lowering of the valve, and so that, when said shoe is returned to said rest position, said abutment member is swingably withdrawn from the path of travel of said rod to permit upward movement of the latter and lowering of the valve after which said rod blocks swinging of said abutment member into said path of travel and prevents radially outward movement of the shoe from its rest position.

6. In a centrifugal machine; the combination according to claim 5, further comprising a switch adapted to be interposed in circuits for controlling the loading and spinning of the basket, a switch actuating arm projecting into the path of travel of said arm and biased to a lowered position wherein said switch is open, said arm being engaged and raised by said rod during upward movement of the latter to close said switch.

References Cited in the file of this patent UNITED STATES PATENTS 302,611 Weston -1 July 29, 1884 1,414,525 Prestwich May 2, 1922 1,633,570 Carroll June 28, 1927 2,249,210 IOhnsOn July 15, 1941 2,377,070 Campos May 29, 1945 2,461,764 Olcott Feb. 15, 1949 2,463,874 Hertrich et al Mar. 8, 1949 2,667,974 Hertrich Feb. 2, 1954

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