US3627180A - Stopper rod with assembly for alignment with nozzle - Google Patents

Abstract

A stopper rod assembly for a molten-metal-dispensing ladle is provided with a double clevis connection between its vertical stopper and its support arm such that the stopper rod can and will align its flow controlling lower end or head portion with the tap hole in the ladle, irrespective of misalignment that may have occurred with reference to its supporting arm, associated slide rod, etc.

Description

United States Patent inventor Harry '1. Montgomery New Castle, lPa.

Appl. No. 10,805

Filed Feb. 12, 1970 Patented Dec. 14, 1971 Assignee Pennsylvania Engineering Corporation New Castle, Pa.

STOPPER ROD WITH ASSEMBLY FOR ALIGNMENT WITH NOZZLE 5 Claims, 13 Drawing Figs.

ILLS. Cl 222/505, 222/559, 222/563 lint. Cl B220 37/00 Field of Search 222/DlG. 5, 563, 559', 505; 64/17 References Cited UNITED STATES PATENTS McFadden Stillwagon, .ir. Edgar, Jr. Davis et al.

Matta Primary Examiner- Robert B. Reeves Assistant Examiner- David A. Scherbel AtmrneyGreen, McCallister & Miller 64/ i 7 X 222/D1G. 5 222/D1G. 5 222/D1G. 5

ABSTRACT: A stopper rod assembly for a molten-metaldispensing ladle is provided with a double cievis connection between its vertical stopper and its support arm such that the stopper rod can and will align its flow controlling lower end or head portion with the tap hole in the ladle. irrespective of misalignment that may have occurred with reference to its supporting arm, associated slide rod, etc.

alezmeo PATENTED m: 1 4 I971 SHEET 2 BF 2 ml MENTOR. Harry 7'. Monfgomery HIS ATTORNEYS STOPPER ROI) WI'II-I ASSEMBLY FOR ALIGNMENT WITH NOZZLE This invention relates to a new and improved stopper rod device, apparatus or assembly which will assure full closing-off alignment of a rod end or head with the tap hole cavity in, for example, a molten metal teeming ladle. A phase of the invention deals with means enabling a suspended stopper rod to self-align itself with a tap hole, even where mounting or sup porting means for the rod has been bent out of alignment.

The ability of a typical bottom teeming-type ladle, such as used in steel mills for processing molten metal, to perform correctly depends on the operation of the entire stopper rigging, and particularly on the alignment of the stopper rod relative to the tap hole. If the stopper rod does not set properly and fully in the tap hole cavity within the bottom lining of the ladle, a so-called "runaway ladle exists. As a result, molten metal will pour from the tap hole uncontrolled by the ladle operator. This is an extremely dangerous condition leading to possible loss of life and of lesser importance, to damage of equipment, loss of metal, etc.

In the handling of a teeming ladle in a steel mill, tipping by the crane to deslag it and other handling operations oftentimes causes damage to the stopper assembly and particularly, to the vertical slide rod of the crossarm that is carried by it to support the stopper rod. Angularity resulting from bending of the rod or cross over causes the stopper rod to no longer hand in a fully vertical position. Since the parts are rigidly attached together, the stopper rod cannot correct the misalignment thus produced and will, as shown in FIG. ll, move into a poor fitting or completely nonfitting position with respect to the tap hole.

Although it has heretofore been considered necessary to maintain a rigidly secure connection between the three parts of a stopper assembly to assure a positive and sure opening and closing of the ladle tap hole, it has been discovered that it is this very feature which gives rise to the problem involved in assuring a full closing action of the stopper head when the assembly has in some manner been damaged or bent out of full alignment. Further, it has been discovered that the fixed relation requirement is self-defeating in this connection and that a full and effective aligning action can be assured by suspending the stopper rod per se through a swivel or swingable joint. It was determined that a proper form of joint will permit the rod, under the combined action of the force of gravity on its relatively heavy longitudinally extending body, as used with a frustoconical entrance-shaped wall to the tap hole, to accomplish a positive and even more effective closing action of the stopper rod when the parts are fully aligned, and that it will assure a continuance of such a type of action when the parts have been bent or damaged during ordinary steel mill usage. By such an approach which is contrary to the previous teachings of those skilled in the art, l have been able to fully meet the problem involved.

In the drawings,

FIG. I is a fragmental view in elevation illustrating the difficulty that may occur, using a conventional rigid type of stopper rod mounting, after the support assembly has been bent or distorted out offull alignment.

FIG. 2 is a vertical view in elevation through a side portion of a teeming ladle illustrating a stopper rod assembly or construction of the invention and showing the closure end or head of the stopper in an aligned closed position with respect to a tap hole in the ladle.

FIG. 3 is a fragmental side view in elevation on the scale of and of the structure of FIG. 2, taken at right angles with respect thereto, and showing the parts in the same relative positioning as in FIG. 2.

FIG. 3A is a fragmental view on an enlarged scale showing the lower end portion of the stopper rod assembly in the position of FIG. 3.

FIGS. 4, 5, h and 7 are enlarged fragmental, horizontal sections, taken respectively along lines IV--IV, V-V, VI--VI and VII-VII ofFIG. 2.

FIG. 8 is a vertical fragmental section on the scale of FIGS. 4 to 7 and taken along the line VIIl-VIII of FIG. 3.

FIG. 9 is a further enlarged fragmental vertical view of swing connecting means shown particularly in FIG. 2, but taken in the direction of line IX-IX of such figure or, in other words, turned FIG. I0 is a view on the scale of and similar to FIG. 9, but taken from the side of the construction as FIG. 2.

FIG. Ill is an enlarged fragmental horizontal section taken along the line XI-Xl of FIG. I0; and FIG. 12 is a fragmental vertical view on the scale of FIG. I l and of structure shown in FIG. 10.

In carrying out the invention, a stopper rod A is, at its upper end, connected by dual-acting swivel joint F to and suspended from and supported by an overhead crossarm assembly B which, at its other end, is securely mounted on a slide rod assembly C for up and down or vertical reciprocating movement with respect to a teeming ladle D. The stopper rod A has a stopper head or closure part 21 removably mounted at its lower end to cooperate with a tap hole assembly E.

In FIGS. 2 and 3, a typical ladle D is shown as having an outer metal shell wall enclosure I0, an outwardly projecting reinforcing bloclt I00 secured to the wall 10 for mounting a clevis 57, and a side-extending block 10b secured to the wall I0 for cooperating with an angle piece 65 that is used in cooperation with an angle piece 66 having a side-positioned mounting on the rod assembly C. As shown particularly in FIG. 2, the metal shell wall It) has an inner refractory lining II which, at-its lower end, is provided with a pour opening within which the tap hole assembly E is mounted. A frustoconically shaped pour ring 12 of refractory material is adapted to seat within an upper, enlarged portion of the tap hole and to cooperate with a cylindrical, vertically extending, refractory pour nozzle 13 and a refractory sleeve 14. As shown, the nozzle 13 has a pour opening, bore or passage 13a therethrough that, at its upper end, terminates in a frustoconical cavity or mouth to cooperatively receive, align and seat a somewhat conical or rounded convex end portion 21a of the stopper head 21 when the pour passage 13 a is to be closed off. An adapter washer I5 and a metal mounting flange 16 are used to position the nozzle 13 in its through-extending relation with respect to the shell wall 10. The stopper head 21 is removably held in position with respect to a vertically extending, hollow, stopper rod refractory sleeve 20 by means of an inset, threaded collar 21b which, at its lower end, is engaged by a head portion of a through-extending metal stopper rod 22.

As shown particularly in FIGS. 2, 9 and R0, the rod 22 extends along the hollow center of the refractory sleeve 20 and has an upwardly outwardly extending, threaded stem end portion 22a. A washer and nut assembly 23, 24 is employed to draw the head of the lower end of the rod 22 up into engagement with the inset collar 21b and to hold the rod in an assembled relation with respect to the enclosing refractory sleeve 20. The swivel joint F has a lower clevislike part 25 provided with a threaded bore hole 250 therein to removably receive the threaded upper stem end portion 22a therein. A nut 26 serves as a lock nut with respect to the mounting of the threaded end 22a within the threaded bore hole 25a.

An upper clevis part 35 of the same general construction and shape as the lower clevis 25 is adapted to cooperate therewith and provide a somewhat universal type of swivel joint connection therebetween. The lower clevis 25 has a pair of spaced-apart mounting wings or ears 25b at its upper end that define a rounded, concave, upwardly open mouth opening therein and are adapted to receive a through-extending, headed, large diameter bolt 30. The bolt 30 is secured in position to extend across the open mouth defined by the wings or ears 2512 by means of its headed portion, a washer 3i and cotter pin 32 (see also FIGS. ill and 12;). The upper clevis 35 also has a pair of spaced-apart wings or ears 35b which are open downwardly and define a rounded concavity therebetween to removably receive a through-extending, headed, smaller diameter bolt 36. As shown in FIGS. 10 and I2, the bolt 36 is removably mounted at right angles to the bolt 30 by means of its head portion, a washer 37 and cotter pin 3%.

'As particularly illustrated in FIGS. 11 and 12, the bolt 36 has a central portion 36a of square or polygonal shape which fits in a complementary manner within and extends through a cross-extending bore 30a in the bolt 30. Thus, the bolt 36 will permit turning, swiveling or pivoting of the ears 35a thereabout, but will not, itself, turn or pivot with respect to the larger diameter cross-extending bolt 30. Also, the bolt 30 permits swiveling or pivoting of the ears 25b but will not, itself, pivot with respect to the bolt 36. To permit removal and insertion of the bolt 36 (see FIG. 1 1), a bearing sleeve 39 is shown provided in one ear or wing 35b that may be removed to bypass the square or polygonal central shaft portion 36a. It is thus apparent that the lower clevis or part 25 of the swivel joint F may be pivoted or swung back and forth on and with respect to the bolt 30, and that the upper clevis part 35 may be swung back and forth at right angles to the swinging movement of the clevis 25 on the bolt 36. Also, since both the clevis parts 25 and 35 are threadably carried on the structure, they may be adjusted in a turned positioning or angularity to also compensate for any bending of the structure.

The dual swivel joint F is carried in a downwardly projecting relation from an extending end of cross-extending support assembly B to enable stopper head 21 to seek, accurately align with and close off molten metal flow through the nozzle 13. A threaded mounting stem 40, see particularly FIGS. 2, 9 and 10, extends through a bore hole or slot 450 in the forward end of a cross-extending arm member 45 and is adjustably secured in position with respect thereto between washer and bolt assemblies 42, 41 and 43, 44. The lower end of the stem 40 is adjustably secured within a threaded bore hole 35a in the upper end of the clevis part 35. The nut 41 thus serves as a lock nut for securing the stem 40 in a desired vertical angular position within the threaded bore 35a, and provides for any suitable desired turned position of the upper clevis 35 with respect to the arm 45.

A vertical post 46 having an upwardly converging or somewhat conical shape is adapted to be removably fit upwardly within a similarly shaped bore hole or slot 45b in the other end of the arm 45. A cross-extending key 48, see particularly FIGS. 2 and 3, holds the post 46 in a secure, mounted position within the arm 45. The post 46 is shown provided with an eyelet or eyeletlike pin 47 that is secured in position therein by a threaded stem and a lock nut 47a for receiving a hook of an overhead hoist.

The lower end portion of the post 46 has a centrally disposed connection 460 with an upper end of a vertical operating rod or shaft 50 of square section. As shown in FIG. 2, a pivot pin 56 is carried by the operating rod or shaft 50 and is employed to provide a pivot connection for suspending a heat shield 55. As shown particularly in FIGS. 2 and 6, an upper sleeve bearing or bushing 51 slidably carries the shaft 50 and is removably mounted within an upper end of an outer sleevelike housing 53 by means of bolts 51a (see FIG. 2). A similar lower sleeve bearing or bushing 52 engages the shaft 50 adjacent its lower end, see also FIGS. 6 and 7. The bearing or bushing 52 is shown secured in position within the housing 53 by a pair of threaded bolts or screws 52a (see particularly FIGS. 6 and 8) and has a side opening therethrough to bypass a clamping screw assembly 68. The assembly 68 has an operating arm and a clamping pin end portion adapted to engage within a vertical recess or groove 50a along the shaft 50 to clampingly hold the shaft in a desired vertically adjusted relation within and with respect to the housing 53. When stopper rod assembly A is to be operated as, for example, raised or lowered, then the operating handle of the clamping screw assembly 68 will be turned to release the shaft 50 as a preliminary step.

The housing 53, adjacent its upper end portion, is protected by a sleevelike heat shield 55 that may be suspended by the pin 56. A bifurcated mount 58 is secured, as by welding, about a portion of the sidewall of the housing 53, adjacent its upper end, and (sec FIGS. 2 and 4) carries a cross-extending pivot pin 59 that is secured to its forks by wedge pins 590. A clevis 57 having a pair of spaced-apart lugs extends from the block 10a and the shell wall 10 to pivotally receive the pin 59. The lower end portion of the sleeve housing 53 has angle piece 66 secured, as by welding, about a portion of its sidewall, and bolt and nut assemblies 67, see particularly FIGS. 2 and 5, secure the second angle piece 65 to extend above and over the block 10b. The angle piece 65 is adapted to rest on the block 10b and permit pivotal movement of rod assembly C with the pin 59 Referring particularly to FIGS. 2, 3 and 7, a split sleeve collar 70 is swivelly mounted about the housing 53 through the agency of an intermediate ring member 71. The ring member 71 may be a reinforcing integral part of the housing 53, but the collar 70 is removably mounted in position thereon by bolts 70a. The collar 70 has a projecting ear or lug 701: which pivotally suspends a pair of vertically downwardly extending support arms 75 by means of a pivot pin 76. The vertical arms 75 have, as shown particularly in FIG. 2, a group or series of vertically spaced-apart holes 750 therealong for providing an adjustable connection with a betweenpositioned vertical leg 77a of a crank arm 77. The vertical leg 77a also has a series of holes which further the adjustably mounted connection, as used with a pivotal connecting means, such as a nut and bolt or a bolt and cotter pin assembly. A horizontal or lower leg 77b of the crank 77 has a pivot pin connection at 93 with a downwardly projecting, flattened, connecting finger element 91. The crank 77 is adapted to swing on the horizontal axis of the ring member 71 about 45 to, in turn, swing the arms 75 and the collar 70 therewith.

It will be noted in FIG. 8 that the lower end portion of the operating shaft 50 terminates adjacent the bottom of the housing shell 53 when the stopper rod A is in the closing" or fdown" position of FIG. 2. A spacer sleeve or collar 86 has a bore therethrough to loosely fit over the upper end of an operating stem or screw 85. The spacer collar 86 may be tightened up against the lower end of the sleeve housing 53 on the threaded stem by an internally threaded adjustable nut 89 which may be an integral part of the collar 86 and which has an adjustable, threaded fitting on the screw 85. As shown particularly in FIGS. 2, 3 and 3A, the lower end of the screw or threaded stem 85 has a reduced, smooth cylindrical portion 85a which may be engaged by a key 85b for retaining it in a nontuming relation within a two-part coupling block 90. The block structure is secured together by bolt and nut assemblies 92.

The spacer collar 86 and the nut 89 may have means, such as handle 87, for facilitating turning adjustment of the nut 89 between a maximum upper position, as noted in FIGS. 2 and 3, and a maximum lower position (in abutment with the twopart block 90) to provide a total maximum amount of travel of about l3 inches. The finger element 91 rotatably projects upwardly through the central bore of the block assembly 90 to, at its upper end, engage the lower end of the stem 85. The finger 91 has a circular head portion 91a at its upper end that is provided with a lubrication groove therein, and that serves to rotatably retain the finger 91 within the block 90. A reduced, circular stem portion 91c extends outwardly through the block 90 and has a mounting collar 91b secured thereon.

The crank 77 has an outwardly converging, mounting lug portion 77c which is adapted to fit within an open, outwardly diverging cavity defined by a bifurcated end portion 78a of a piston or operating rod 78. Pin 79 secures the lug 77c within forks of the bifurcated portion 780. The rod 78 may be connected at its outer end for vertical reciprocation, as by means of a fluid motor or other suitable actuating agency, to thus cause vertical movement of the finger 91, the screw shaft 85 and the operating shaft 50, as limited in its maximum upward movement by engagement of the collar 86 with the lower end of the bearing 52 (see FIG. 8). Horizontally swiveling of the crank 77 by means of the collar 70 enables the operating connection to the crank to be facilitated from the standpoint of a particular plant installation or a suitable location for the fluid or other type of motor actuating means.

The invention eliminates the difficulty that in an exaggerated manner has been shown in FlG. l, where the head of a stopper rod, by reason of a bending of the support arm or of the operating structure, changes the fixed alignment of the stopper rod, such that its stopper head is located to one side of or out of alignment with an entry mouth portion of the pour hole. Even a slight misalignment will cause difficulty, since even if the head of the rod does enter the mouth portion of the pour hole, it does not have a self-aligning feature and will not fully seal-off the hole or passage. If an attempt is made to force a rigidly suspended or mounted refractory stopper rod into a full seating position under such conditions, there is also the danger of fracturing either the refractory head of the rod or refractories associated with the pour opening.

The present invention provides a swivel mounting that, contrary to the prior art teachings, eliminates a rigid suspended support of a refractory stopper rod and obtains a full seating or shutting-off closing action with respect to the entry mouth of the pour hole, irrespective of whether the operating assembly for the rod is in an initially installed fully aligned relation or not. In fact, the present construction eliminates the necessity for highly accurate aligned mounting of the stopper assembly with respect to the ladle or other apparatus, in that it has self-aligning movement into and out of a seating position with respect to the entry mouth portion of the pour opening or nozzle. This not only eliminates the difficulties which arise when some part of the structure has been damaged or bent, such that using a normal rigid type of construction it would be impossible to fully shut off the pour opening, thus giving rise to a highly dangerous condition, but also minimizes the wear and tear on the inherently somewhat brittle refractory parts of the stopper construction as well as of the lining of the vessel. A dual axis, four-way swiveling action gives full flexibility to the stopper rod which is further enhanced by the feature of enabling a turning or rotative adjustment of it from the standpoint of its suspended mounting from the overhead support arm.

I claim:

1. In combination with a bottom pouring teeming ladle and the like having a vertically extending sidewall and a bottom pour hole, a frustoconically shaped refractory ring disposed within the pour hole, a refractory pour nozzle extending from said ring through the pour hole and provided with a conically shaped upper mouth portion, a vertically extending and fully vertically self-aligning stopper rod assembly operatively mounted in a horizontally spaced relation with respect to inner and outer surfaces of said sidewall adjacent said pour hole, said assembly having a refractory-enclosed stopper rod adapted to extend vertically in a spaced relation along the inner surface of said sidewall, a stopper head on the lower end of said rod having a forwardly converging convex frustoconical shape to loosely guidably center within said ring and directly within the frustoconical mouth portion of said nozzle when said stopper is moved downwardly to shut off flow of molten metal through said nozzle, an overhead-positioned and horizontally extending crossarm member, connecting means providing a universal type of swivel joint and adjustably suspending the upper end portion of said stopper rod from an inner end portion of said crossarm, a vertical post at its upper end removably secured to the outer end of said crossarm to extend downwardly therefrom, an operating rod of polygonal section extending vertically downwardly from and being connected at its upper end to the lower end of said vertical post for up and down movement with respect to said sidewall, a vertical housing along said operating nod, said housing having a polygonal inner wall portion therealong for vertically slidably and nonrotatably positioning said operating rod therein, a bifurcated mount swingably mounting an intermediate length portion of said housing on and in a spaced relation with respect to the outer surface of said sidewall, a sideextending block secured to the outer surface of said sidewall in a vertically downwardly spaced position below said bifurcated mount, a slide member secured to said housing and proectmg therefrom towards said sidewall and having a honzontally slidable positioning on an with respect to said side-extending block, means carried by a lower end portion of said housing and cooperating with said operating rod for moving said rod vertically upwardly and downwardly within said housing and thereby moving said stopper rod into and out of closing-off engagement within the frustoconical mouth portion of said nozzle; said connecting means, slide member, and bifurcated mount cooperating to assure a full vertical alignment of said stopper rod with respect to said pour hole irrespective of warping and other misshaping of said arm member, said post and said operating rod; said connecting means providing a vertical swing adjustment of said arm member with respect to and between said stopper rod and said operating rod, said connecting means and said bifurcated mount cooperating to provide vertical swinging movement of said housing and said operating rod with respect to said sidewall, and block and slide member providing for inner and outer horizontal slidable movement of said housing and said operating rod adjacent lower end portions thereof with respect to said sidewall.

2. ln a combination as defined in claim 1, a collar mounted adjacent a lower end portion of said housing, a downwardly extending vertical stem adjustably carried within the lower end portion of said housing and in a cooperating relation with respect to the lower end of said operating rod, and a crank and lever mechanism pivotally mounted on said collar and pivotally connected to a lower end of said stem for moving said operating rod vertically upwardly and downwardly within said housing.

3. In a combination as defined in claim 2, said operating shaft having a vertical recess portion along one side of its lower end portion, a clamping screw assembly operatively mounted on said housing adjacent a lower end thereof and having a clamping pin and adapted to engage within said vertical recess portion of said operating shaft for holding said shaft in a vertically adjusted relation within and with respect to said housing.

4!. In a combination as defined in claim 3, a two-part block assembly mounted in a clamping relation over the lower end portion of said stem, said stem having key means for retaining it in a nontuming relation with respect to said block assembly, and a finger projecting downwardly from said block and pivotally connected to a crank member of said crank and lever mechanism, and means extending from said mechanism for actuating said crank to move said finger, said block assembly, and said stem as a unit vertically with respect to said housing.

5. In a combination as defined in claim 4, said collar being a spacer collar adjustably positioned on said vertical stem.

s tw a s

Claims (5)

1. In combination with a bottom pouring teeming ladle and the like having a vertically extending sidewall and a bottom pour hole, a frustoconically shaped refractory ring disposed within the pour hole, a refractory pour nozzle extending from said ring through the pour hole and provided with a conically shaped upper mouth portion, a vertically extending and fully vertically selfaligning stopper rod assembly operatively mounted in a horizontally spaced relation with respect to inner and outer surfaces of said sidewall adjacent said pour hole, said assembly having a refractory-enclosed stopper rod adapted to extend vertically in a spaced relation along the inner surface of said sidewall, a stopper head on the lower end of said rod having a forwardly converging convex frustoconical shape to loosely guidably center within said ring and directly within the frustoconical mouth portion of said nozzle when said stopper is moved downwardly to shut off flow of molten metal through said nozzle, an overhead-positioned and horizontally extending crossarm member, connecting means providing a universal type of swivel joint and adjustably suspending the upper end portion of said stopper rod from an inner end portion of said crossarm, a vertical post at its upper end removably secured to the outer end of said crossarm to extend downwardly therefrom, an operating rod of polygonal section extending vertically downwardly from and being connected at its upper end to the lower end of said vertical post for up and down movement with respect to said sidewall, a vertical housing along said operating rod, said housing having a polygonal inner wall portion therealong for vertically slidably and nonrotatably positioning said operating rod therein, a bifurcated mount swingably mounting an intermediate length portion of said housing on and in a spaced relation with respect to the outer surface of said sidewall, a side-extending block secured to the outer surface of said sidewall in a vertically downwardly spaced position below said bifurcated mount, a slide member secured to said housing and projecting therefrom towards said sidewall and having a horizontally slidable positioning on and with respect to said side-extending block, means carried by a lower end portion of said housing and cooperating with said operating rod for moving said rod vertically upwardly and downwardly within said housing and thereby moving said stopper rod into and out of closing-off engagement within the frustoconical mouth portion of said nozzle; said connecting means, slide member, and bifurcated mount cooperating to assure a full vertical alignment of said stopper rod with respect to said pour hole irrespective of warping and other misshaping of said arm member, said post and said operating rod; said connecting means providing a vertical swing adjustment of said arm member with respect to and between said stopper rod and said operating rod, said connecting means and said bifurcated mount cooperating to provide vertical swinging movement of said housing and said operating rod with respect to said sidewall, and block and slide member providing for inner and outer horizontal slidable movement of said housing and said operating rod adjacent lower end portions thereof with Respect to said sidewall.

2. In a combination as defined in claim 1, a collar mounted adjacent a lower end portion of said housing, a downwardly extending vertical stem adjustably carried within the lower end portion of said housing and in a cooperating relation with respect to the lower end of said operating rod, and a crank and lever mechanism pivotally mounted on said collar and pivotally connected to a lower end of said stem for moving said operating rod vertically upwardly and downwardly within said housing.

3. In a combination as defined in claim 2, said operating shaft having a vertical recess portion along one side of its lower end portion, a clamping screw assembly operatively mounted on said housing adjacent a lower end thereof and having a clamping pin and adapted to engage within said vertical recess portion of said operating shaft for holding said shaft in a vertically adjusted relation within and with respect to said housing.

4. In a combination as defined in claim 3, a two-part block assembly mounted in a clamping relation over the lower end portion of said stem, said stem having key means for retaining it in a nonturning relation with respect to said block assembly, and a finger projecting downwardly from said block and pivotally connected to a crank member of said crank and lever mechanism, and means extending from said mechanism for actuating said crank to move said finger, said block assembly, and said stem as a unit vertically with respect to said housing.

5. In a combination as defined in claim 4, said collar being a spacer collar adjustably positioned on said vertical stem.

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