US3393017A - Discharge unit for railway hopper cars - Google Patents

Description

July 16, 1968 J.T. SMITH DISCHARGE UNIT FOR RAILWAY HOPPER CARS 5 Sheets-Sheet 1 Filed May 22, 1967 July 16. 1968 J. T. SMITH DISCHARGE UNIT FORv RAILWAY HOPPER CARS 5 Sheets-Sheet 2 Filed May 22, 1967 July 16, 1968 J. T. SMITH DISCHARGE UNIT FOR RAILWAY HOPPER CARS 5 Sheets-Sheet 5 Filed May 22. 1967 July16.1968 J.T. SMITH 3,393,017

DISCHARGE UNIT FOR RAILWAY HOPPER CARS Filed May 22, 1967 s Sheets-Sheet 4 *iN I I h? R S T, "ETL Rx w m 5 N R, K r=n r g 9" we 9-- 5;" e v E July 16, 1968 J.T. SMITH DISCHARGE UNIT FOR RAILWAY HOPPER CARS 5 Sheets-Sheet 5 Filed May 22, 1967 QNN United States Patent 3,393,017 DISCHARGE UNIT FOR RAILWAY HOPPER CARS James T. Smith, Wilmette, Ill., assignor to Keystone Railway Equipment Company, Chicago, Ill., a corporation of Delaware Filed May 22, 1967, Ser. No. 640,264 9 Claims. (Cl. 302-52) ABSTRACT OF THE DISCLOSURE A hopper discharge unit for hopper railway cars is selectively alterable for gravity discharge of materials of large aggregate size and also for vacuum discharge of finely divided materials from the hopper chute. The unit includes pinion and rack mechanism similar to that shown in James T. Smith Patent No. 3,085,517 for opening or closing a sliding door plate at the bottom of the hopper, and it also serves to selectively move a vacuum discharge assembly between a functional position below the hopper chute whereby finely divided material may be vacuum discharged through a nozzle assembly and a storage position whereby the hopper may be used for holding other materials and for discharging these materials by gravity feed alone. The vacuum discharge assembly is slidably supported for motion between the position below the chute and a storage position away therefrom. By manually maniplating a latching mechanism, the assembly may be attached to the moving portion of the door and the pinion and mechanism whereby movement of the pinion mechanism slides the vacuum assembly between its operational and storage positions.

Also disclosed is a novel locking mechanism for a pinion-and-rack type of railway hopper car door assembly including a sleeve mounted over the pinion axle for relative rotation thereabout, operating arms affixed to the sleeve on either end thereof, a hooking member centrally aflixed to the sleeve and a fixed eyelet on the chute for receiving the hooking member when the pinion axle is in the closed position. By revolving the arms, the hooking member may be caused to enter the eyelet for locking the rack and pinion mechanism in the closed position.

Cross reference to related patents James T. Smith, Patent No. 3,085,517, dated Apr. 16, 1963, entitled, Sliding Hopper Closure Discharge Assembly.

Background of the invention The invention relates to railway hopper cars and particularly to hopper car discharge unit that is selectively and easily adaptable to either full gravtiy discharge or to vacuum discharge. The discharge unit of the present invention is positioned at the base of a railroad hopper and is secured thereto either permanently or semi-permanently during use. The railroad discharge unit of the present invention employs a rack and pinion mechanism which is generally similar to that shown in the present inventors issued patent, entitled, Sliding Hopper Closure Discharge Assembly, U.S. Patent No. 3,085,517, which issued on Apr. 16, 1963.

Hopper cars have been in general use in the United States for well over 60 years. During this period the use of these cars has been expanded from carrying a few staple items, such as coal and crushed rock, to the carrying of a great number of diiferent types of bulk products. The use of hopper cars for moving bulk materials of varying natures has resulted in specialized hopper cars for various materials. The nature of some of the bulk materials to be moved requires either special adaptation of existing hop- 3,393,017 Patented July 16, 1968 ice per cars or specially constructed hopper cars. Some of these materials, as for example wheat and cement, are produced or used seasonally. As such, the need for transporting these products is also seasonal. Hopper cars which are specially adapted to be used for such seasonal products would remain unused and idle during the off seaon. Futhermore, the need for transporting some of these is essentially uni-directional. For example, wheat is shipped from the farming area of the Midwest to the ports of Chicago. Cars specially equipped to handle wheat are used in the shipment of wheat from the farmland areas to Chicago and as they often cannot be used for other bulk goods, must be "dead-headed back to the farm areas. That is, shipped back empty to the loading area. This wasted shipping space increases the costs of operation of such specialized cars as well as increasing the cost of operating the railroads using such cars.

It is an object of the present invention to provide a hopper discharge unit that prevents this waste by readily adapting the railway hopper car to handle either finely divided materials such as wheat and coarser materials such as rock or coal.

A further object of the invention is to provide a hopper discharge unit which very quickly discharges the entire contents of the hopper unit.

Brief description of the drawings The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:

FIG. 1 is a fragmentary plan view, with parts broken away to show the interior construction and hidden parts shown in dashed lines, of a hopper discharge unit for a hopper car constructed in accordance with the present invention;

FIG. 2 is a fragmentary longitudinal sectional view of the unit of FIG. 1 as seen from line 22 in that figure with a portion of the hopper of a railway car shown in phantom to illustrate the manner of attachment thereto and a moved position of part of the unit illustrated in dashed lines;

FIG. 3 is a transverse fragmentary sectional view of the unit of FIGS. 1 and 2 as seen from the lines 33 of those figures;

FIG. 4 is a transverse fragmentary sectional view of the unit of FIGS. 1 to 3 as seen from the line 44.of FIG. 1;

FIG. 5 is a sectional view similar to FIG. 2 showing the door plate in open position and the hopper in condition for vacuum discharge;

FIG. 6 is a fragmentary plan view of a second hopper unit constructed in accordance with the present invention;

FIG. 7 is a transverse fragmentary sectional view of the second embodiment depicted in FIG. 6 as seen from the line 77 in that figure;

FIG. 8 is a similar view as FIG. 7 with parts shown in a moved position; and

FIG. 9 is a transverse elevational View, partially in section, as generally seen from the line 99 in FIG. 6.

Detailed description Referring to FIG. 1, there is depicted a discharge unit designated by the numeral 10. The unit 10 includes a discharge chute 12 comprising four slanting wall members 12a, 12b, 12c and 12d each of which may be for-med from stock A" steel sheet. The members are joined toverse" members 1212 and 12d abutting against and joined to opposite ends of the longitudinally disposed members 12a and 120. The members 12a to 12d all are slanted at approximately 45 to the horizontal to form an upward opening shadow-box-like structure that may funnel material from the hopper 13 to which it may be attached and of which it may form an extension as shown in FIG. 2. The chute 12 bottoms at a horizontal plane at which a slidable rectangular door plate 14 is disposed. The door plate 14 when in its closed position is maintained there, in part, by three outstanding hold-down lugs 15' spaced along member 12d and preferably aflixed thereto by welding. These lugs 15 deform slightly when the plate 14 assumes its closed position and they bear against the plates upper surface to prevent it from moving upward and possibly causing a leakage of material from the hopper. The forward edges 14a of the plate when in the closed position overlies a horizontal ledge 19 which extentls'along the bottom of the wall 12d between the channel members 16 and 17. The plate 14 is wedged between this ledge 19 and the lugs 15 when in the closed position. The longitudinal edge portions of plate 14, as best shown in FIG. 3, rest on the upper edges of and span transversely between two vertically disposed channel members 16 and 17. The bottommost edges of member 12a may be affixed as by welding at 18a to the top of the channel member 16 while the number 120 may be similarly afiixed at 18c. Together the welded members 12a and 12c form a longitudinal track for guiding the door plate 14.

At the bottom of each structural channel member 16, 17 there is a longitudinally extending lip 20 and 21, respectively, preferably formed by welding longitudinally extending rigid strips 22 and 23 to the bottom surface of the members 16 and 17 so that they protrude inward. The strips extend for approximately the full length of the members 16 and 17 and provide support for a vacuum pan assembly 30.

The vacuum pan assembly extends between the channel members 16 and 17 and has its lower longitudinal edges resting on the lips 20 and 21. As best seen from FIG. 1 the pan assembly 30 is generally rectangular in shape opening upward and is sized to approximately extend under the opening formed when the door 14 is opened. When the unit 10 is to be used for discharging a finely divided material by vacuum the assembly 30 is positioned, as shown in solid lines in FIGS. 1 to 5, under the closed position of the door plate 14. As shown in FIG. 2, the forward wall 31 of the assembly 20 is canted to the vertical and rests against a similarly canted wall 32 which spans between the members 16 and 17 and is afiixed thereto by welding. The wall 32 extends upward to the member 19 and may be formed integrally therewith. The lower forward edge 33 of the unit rests on a supporting member 34 which forms a lip or flange 35 extending between the members 16 and 17. The member 34 is preferably welded to the lower surface of the members 16 and 17 and forms a forward extension of the lips or flanges 20 and 21 formed by the strips 22 and 23.

The vacuum pan assembly 30 defines an upwardly opening pan with material flow dividers and deflectors therein. Beneath the flow divider and deflector arrangement there is a sheltered-area C having an outlet 37 opening thereinto from each side of the assembly 30. In register with the outlet 37, when the assembly 30 is in its operating position, is a similarly sized opening in the channel members which opens into vacuum nozzle assemblies which are permanently aflixed to the members 16 and 17 and extend outwardly therefrom. The assemblies 40 are adapted to having vacuum discharge hoses attached thereto for extracting material from the unit 10.

More specifically, the assembly 30 comprises a generally rectangular floor plate 38 about whose edges are tion to the slanted forward wall 31, the assembly includes two longitudinallyextending vertical side walls 41 and 42, having the openings 37 defined therein, and a slanted rear wall 43.

The pan assembly 30 includes flow dividers and deflectors afiixed therein. These include two transverse extending flow dividers 39 of an inverted V-shape in cross section. The dividers are preferably formed from rectangular steel sheets bent along the longitudinal center line. Horizontal brace members 39a (FIG. 3) may be welded between the opposite walls of the dividers 39 to hold their configuration. The lower transverse edge of the dividers 39 are spaced from the floor 38 by means of V-shaped separators 36. Deflectors 139 which extend longitudinally are affixed ateither end of thethree transverse troughs T T and T formed by the dividers 39 and the end walls 31 and 43. These deflectors 139 are generally triangular shaped sheets extending from the top of either the wall, 41 and 42 at an angle to the horizontal until they reach the floor 38. The side edges of the deflectors 139 are affixed, as by welding, to the upward facing walls of the dividers or walls between which they extend.

Permanently aflixed to the rearward edge of the door plate 14 by means of a pair of transversely spaced brackets 50 is a rack and pinion mechanism 51. In many respects the mechanism 51 is similar to that shown in the aforementioned Patent No. 3,085,517. This mechanism includes an axle 52 carried in bearings 53 which are afiixed to the brackets 50. Also aflixed to the axle 52 are pinions 54 which mesh in racks 55. At one or both ends of the axle '52 are aflixed handle sockets 56 by which the axle 52 and pinions 54 may be rotated and consequently moved along the racks 55. Because of the brackets 50 and bear ings 53 the door 14 is moved longitudinally between the closed position as sh wn and an open position in which it overlies the racks 55.

Affixed to the upper surface of the plate 14 is a transverse stopper bar 78 which makes contact with the outer and lower surface of the wall 12b to stop the forward travel of the door plate 14 when it assumes its closed position.

As best shown in FIG. 4 the bearings 53 each include a guide member 57 having a cutout portion 58 for receiving a guide rail 59. One of the rails 59 is affixed to the inside of the back of the members 16 and 17, forward of the closed position of the door 14 to guide the moving portion of the rack and pinion assembly 51.

In moving longitudinally the door plate 14 passes through a horizontal slot formed between a horizontal flange extension 12!) of the wall 12b and a support member 61. ('FIG. 2). The member 61 is preferably welded to a horizontal transversely extending planer member 62. Further guidance for the d or plate as it is moved longitudinally by the rack and pinion assembly 51 is provided by horizontal guidance flanges 63 extending longitudinally at the base of the walls 12a and 120 from the flange 12b for a portion of the extent of the walls 12a and 120.

Below the member 62 and spaced therefrom is another transverse planer member 70. The member 70 has an upper surface 71 which lies in the same plane as that of surface 21 and has a forward edge 72 that underlies and supports the rearward transverse bottom edge 73 of the pan assembly 30.

In accordance with one aspect of the invention a locking mechanism is provided including a hollow cylindrical sleeve '81 having an inside diameter slightly greater than the outside diameter of the axle 52. The sleeve 81 is mounted about the axle 5 2 between the bearings '53. The sleeve 81 and the axle 52 may rotate relative to one another. Aflixed to either end of the sleeve 81 are arms 82 preferably f rmed from steel plate and designed to project outward traversely from the sleeve lock to terminate above the racks 55. The outer terminal ends of the arm 82 have holes 83 made therein. The holes function to receive a shipment seal bond which may be passed through the hole 83 and through the rack 55. The arms 82 are made such that they clear the pinions '54 and may be rotated over to lay on the top surface of the members 50.

'Also affixed to the sleeve 81 and outstanding therefrom is a hooking member 8 5. Rotation of the arms 82 revolves the sleeve 81 and thus the hooking member 85. Affixed to the rearward portion of wall member 12b so that the hook member 85 may selectively enter therein is an eyelet 185. The eyelet 185 is formed by a U-shaped bar whose ends are welded or otherwise suitably afiixed to the wall member 12b. Rotation of the arms 82 may move the member 85 into the eyelet 185 whenever the door 14 is in its closed position. Counter-rotation of arms 82 unlocks the door and allows it to be opened.

In ccordance with the primary aspect of the present invention, means are provided for removing and restoring the pan assembly 30 from its position below the chute 13. These means include manually operated coupling means generally designated 90-, for coupling the pan assembly 30 to the moving portion of the door plate 14 and pinion and rack assembly 51. The means 90 includes an L-shaped handle bar 91 which is pivotally mounted by having one of its members 9111 seated in bearing members 92 and 93. The bearing member 92 is affixed to the bottom of the rearward edge of door plate 14 to depend therefrom and has a hole formed in it to receive the member 91a. The bearing member 93 is generally L-shaped in side view and is afiixed to the upper surface of the plate 14 and has a portion that depends over the rearward edge of the wall 14 to be spaced from, but aligned with the member 92 and to have a hole therein to receive the member 91a of the handle 91. Afiixed to the member 91a between the members 92 and 93 is a stud 95. The stud 95 lies roughly in the same plane as that of the handle 91 so that when the handle 91 is moved upward to a vertical position the stud 95 depends downward, as shown in phantom in FIG. 4. If the handle 91 which is normally horizontal is operated and moved upwardly when the door 14 is in its closed position and the vacuum pan assembly 30 is positioned below chute '13, the stud 95 will enter a stud socket 96. The socket 96 is afiixed to the pan assembly 30 and includes two vertically disposed longitudinally extending parallel, but spaced, walls 96a and 96b and at two spaced transverse vertical walls 960 spanning between the walls 96a and 96b, to form the socket for receiving the stud 95. By manually moving the handle 91 the stud 95 is caused to enter the socket 96.

The vacuum pan assembly 30 may be simply removed from or restored to beneath the chute 13 by locking the pan assembly to the plate 14 in the manner above described. It is removed, as the plate 14 is moved to open position, a large opening is formed for gravity discharge through the hopper. This opening is bounded by the memthe FIG. 4 position. The door plate is moved to the right as shown in FIG. 5 and the lading is withdrawn from the nozzles 40 through the previously described chambers C and the opening in the pan assembly.

Toprovide improved structural rigidity for the unit 10, an L-shaped, in cross section, member 9 is afiixed between the channel members 16 and 17 at the rearward end of these members. The pair of stops 9a are afiixed to the cross member 9 to stop the moving pinion door 14 assembly in its open position and to prevent override therefrom by contacting the rearward portions of the guides 57.

Suitable detenting means are preferably providedfor detenting the assembly 30 in either its operational position or its storage position to prevent shifting of the assembly 30 during movement of the hopper car.

' Referring now to FIGS. 6 to 9, a second prefer-red embodiment of the invention is depicted. The discharge unit 10' is generally of a similar overall construction and operation as the unit 10 of FIGS. 1 to 5 differs therefrom primarily in the construction of the vacuum pan assembly 30. The assembly 30 includes the upward opening pan shaped structure including a floor 38, transverse end walls 31 and 43 and longitudinal walls 41 and 42. However, an opening 37 is formed therein of a greater transverse and lesser vertical extent than the opening 37 of the prior embodiment. As best seen in FIG. 9, the vacuum pan assembly 30 includes a number of longitudinally disposed flow dividers such as flow dividers 101 and 102. The flow dividers such as 101 and 102 guide the flow towards openings such as the openings 103, 104, and 105, and into the chamber C formed below the flow dividers.

The mechanism for locking the pan assembly 30 of this embodiment to the door 14 is the same as that shown in FIG. 1 and the description will not be repeated.

In both embodiments, the vacuum nozzle assembly 40 is preferably equipped to receive a cap which may in clude a bayonet-type latch 116 positioned on either side thereof, and a handle 117, as well as a locking mechanism including an upstanding lock or seal receiving member 118 and a latching member 119. The member 119 is aflixed to a standard 120 mounted on the nozzle assembly 40. The latching member 119 may pivot in a horizontal plane to latch over, in close fit, the member 118 or to swing freely therefrom.

In removing the cap 115 the latching member 119 is pivoted upward to be free of the member 118 and the cap is rotated so as to advance the bayonet pins of the mechanism 116 out of the bayonet. The cap 115 may be replaced by repeating the process. In operation, the embodiment of FIGS. 6 to 9 is similar to that of the embodiment of FIGS. 1 to 5 and reference may be made to the above description.

As is now obvious, a new and improved hopper discharge unit 'for railroad cars has been disclosed. The discharge unit 10 or 10 may be readily adapted to handle material by vacuum discharge or by gravity discharge. One advantage of the described unit lies in the dual uses, not only the rack and pinion mechanism, but also in the dual uses for the door plate, which can be used to control discharge flow in both the gravity discharge and in the vacuum discharge process by being opened to varying degrees during either of these discharge processes.

While I have shown and described preferred embodiments of my invention, it will be apparent that numerous variations and modifications thereof may be made without departing from the underlying principles of the invention. I therefore desire, by the following claims, to include within the scope of the invention all such variations and modifications by which substantially the results of my invention may be obtained through the use of substantially the same or equivalent means.

I claim:

1. A discharge unit for a hopper of a railway hopper car comprising:

a chute defining an opening;

a vacuum pan assembly;

a door plate slidably interposed between said chute opening and said vacuum pan assembly;

means for mounting said vacuum pan assembly on the car for movement between a first position in which sald vacuum pan assembly is juxtaposed to the openingof said chute and a second position removed from the opening;

a vacuum nozzle assembly mounted for cooperation with said vacuum pan assembly when said assembly is in said first position, to facilitate the vacuum discharge of material from the hopper when said assembly is in its first position;

means for selectively latching said door plate to said vacuum pan assembly; and

means for selectively moving either said door plate alone when said door plate and vacuum pan assembly are unlatched or said door plate and said vacuum pan assembly together when said door plate and vacuum pan assembly are latched so as to selectively adapt the unit respectively for either vacuum discharge or gravity discharge of material carried therein.-

2. The discharge unit as defined in claim 1 in which:

said means for selectively moving said door plate and vacuum pan assembly is of the rack and pinion type and is disposed horizontally for moving either said door plate alone or both longitudinally; and

said means for mounting said vacuum pan assembly includes a pair of spaced longitudinally extending members between which said vacuum pan assembly is supported for sliding between its first and second positions, said longitudinal members also serving to define an opening therebetween for allowing material to be gravitatingly discharged from the unit therethrough when said pan assembly is in its second position.

3. A discharge unit as defined in claim 2 in which:

said pan assembly is of a generally rectangular shape, has a fioor and a plurality of flow dividers, said flow dividers being of inverted V-shape in cross section and are raised above the floor of said assembly to define a chamber between said floor dividers and said floor, said vacuum nozzle assembly opens into said chamber through at least one of said pair of longitudinal extending members for the vacuum removal of finely divided material therefrom.

4. The discharge unit as defined in claim 2 in which:

said rack and pinion type means for selectively moving said door plate and said vacuum pan assembly includes two spaced horizontal longitudinally extending racks and a pair of spaced pinions mounted on an axle with one of said pinions meshing with each of said racks; and

a locking mechanism locking said pinion mechanism in one position relating to said rack, comprising a hook member mounted for rotation about said axle and eyelet defining member affixed to said unit in a stationary position thereon so as to selectively receive said hook member when said axle and pinion are in said one position.

5. The discharge unit as defined in claim 4 in which:

said hook member is mounted on a hollow cylindrical sleeve which is mounted for relative rotation about said axle between said pair of pinions;

said eyelet defining member being of generally U- shape and being affixed to said chute;

and said sleeve having a pair of arms aflixed thereto at spaced transverse positions thereon, one of said arms extending forward to one side and the other of said arms extending outward to the other side, whereby said hooking member may be manually rotated into and out of said eyelet defining member bythe manual movement of one of the arms to lock said axle and said pinions in said one position.

6. The discharge unit as defined in claim 1 in which:

said latching means includes a socket defining means on said vacuum pan assembly and said door platehas a pivotally mounted stud that may be selectively caused to enter and leave the socket defined by said socket defining means, whereby when said stud is in said socket movement of said door plate is transferred to said vacuum pan assembly.

7. The discharge unit as defined in claim 6 in which:

said stud is mounted outstanding from one straight portion of an L-shaped bar which bar portion is pivotally mounted to said door plate by means of a pair supports one of which supports said bar on one side of said stud and the other of which supports said bar on the other side of said stud, said supports being attached to the rear edge of said door plate, whereby said other straight portion of said bar serves as a 8 handle for manually moving said stud into and out of the socket defined by said socket defining means. 8. The discharge unit as defined in claim 2 in which:

two vacuum nozzle assemblies are provided, one on either side of said unit, and at least one of said assemblies is provided with a cap of a hollow cylindrical shape-open at one end and closed at the other, and said nozzle assembly has a bayonet type locking mechanism for reliably securing said cap to said nozzle assembly;

and further an upstanding lock and seal receiving member is afiixed to the outer surface of said cap and a pivotally mounted latchingmember having an opening found therein for closely fitting over said upstanding lock and seal receiving member, is mounted on said nozzle assembly for selecting latching over said lock and seal receiving members when said cap is secured.

.9. The discharge unit as defined in claim 1 in which:

said chute includes four slanting wall members disposed adjacent to one another in a square arrangement with the forward and rearward of said wall members being transversely disposed and the other two of said wall members being longitudinally disposed and with side edges of said members joined together to form an upwardly opening shadow-box-like frame about the opening from said chute, which opening is square in configuration;

said door plate is of a generally rectangular shape and is sized to at least close the opening defined by said chute, said door being horizontally mounted for sliding movement between a closed position in which it closed the opening and an open position in which it is substantially clear of said opening;

- a pair of spaced longitudinally disposed vertically oriented channel members for supporting on their upper surface the longitudinal edges of the said door plate which bridges therebetween one of said channel members being mounted below one of said longitudinally disposed wall members and the other of said channel members being mounted below the other of said longitudinally disposed wall members;

said channel members extending longitudinally beyond said vacuum pan assembly is generally rectangular in shape and opening upward so sized as to extend under the opening formed by said chute and to extend between the channel members and to be supported on and bridge said lips;

said vacuum pan assembly further includes rectangular floor, sidewalls and'a plurality of flow dividers of a generally inverted V-shape' supported above said floor to form a chamber therebetween with openings between the floor dividers and sidewalls for allowing fiow into the chamber;

a lip forming cross-member extends between the upper surfaces of said channel members below the front wall member;

a plurality of hold down legs afiixed to'the inner surface of the forward wall member projecting above said cross-member to hold said door plate therebetween when said door plate assumes its closed position;

said nozzle assembly is mounted projecting outward from one' of said channel members and a secondnozzle assembly is provided mounted on the other of said channel members and projecting outward therefrom;

said nozzle assembly being in connection with said vacuum pan assembly elongated horizontal rectangular openings formed in said channel members and each of said nozzle assembly terminating in a circular outlet;

said selective moving means is a rack and pinion mechanism including two spaced and horizontal, longitudinally extending racks each mounted across from each other and above one of said channel members rearward of said chute and a pair of spaced pinions aflixed to an axle transversely mounted for rotation by means of spaced bearings outstanding from the rear of said door plate, said pinion meshing with said racks, and said axle having lever-receiving sockets at either end for receiving a lever by which the pinions may be rotated to move the door relative to the rack;

one position relative to said rack, comprising a hook a locking mechanism locking said pinion mechanism in 20 member mounted for rotation about said axle and eyelet defining member aflixed to said unit in a stationary position thereon, so as to selectively receive said hook member when said axle and pinion are in said one position; and

said latching means includes a socket defining means on said vacuum pan assembly and said door plate has a pivotally mounted stud that may be selectively caused to enter and leave the socket defined by the socket defining means, whereby when said stud is in said socket movement of said door plate is transferred to said vacuum pan assembly.

References Cited UNITED STATES PATENTS 3,248,026 4/1966 Kemp 30252 3,316,030 4/1967 Kemp 30252 3,343,886 9/1967 Kemp et al. 30252 3,360,302 12/1967 Bagguley 302-52 ANDRES H. NIELSEN, Primary Examiner.

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