US2674383A - Latch tripping mechanism - Google Patents

Description

April 6, 1954 H. w. SANFORD 2,674,383

LATCH TRIPPING MECHANISM Filed Jan. 3, 1945 7 Sheets-Sheet 1 P 1954 H.' N. SANF.ORD 2,674,383

' LATCH TRIPPING MECHANISM Filed Jan. 3, 1945 7 sheets-sheet 2 April 1954 H. w. SANFORD 2,674,383

LATCH TRIPPING MECHANISM Filed Jan. 3, 1945 7 Sheets-Sheet S 14 ,4 w,- f i 0 1a 41 April 6, 1954 H. w. SANFORD M LATCH TRIPPING MECHANISM 7 Sheets-Sheet 4 Filed Jan. 3, 1945 H. w. SANFORD 2,674,383 LATCH TRIPPING MECHANISM 7 Sheets-Sheet 5 April 6, 1954 Filed Jan. 3, 1945 H. W. SANFORD LATCH TRIPPING MECHANISM April 6, 1954 7 Sheets-Sheet 6 Filed Jan. 3. 1945 April 6, 1954 H. w. SANFORD 2,674,333

LATCH TRIPPING MECHANISM Filed Jan. 3, 1945 7 Sheets-Sheet 7 Patented Apr. 6, 1954 LATCH TRIPPING MECHANISM Hugh W. Sanford, Knoxville, Tenn., assignor to The Sanford Investment Company, Wilmington, Del., a corporation of Delaware Application January 3, 1945, Serial No. 571,170

6 Claims. 1

This invention relates to improvements in latch tripping mechanisms, particularly for mine cars and other conveyors having drop bottom doors for discharge of the lading therefrom.

This application is a continuation-in-part of my prior application on Door Latch Mechanisms, filed February 25, 1942, Ser. No. 432,341 which has issued as Patent No. 2,399,708.

In my prior application on door latch mechanisms, l have provided mechanism mounted beneath the car in the trackway and timed to be operated in synchronism with the movement of the car whereby a tripping arm would be moved into position for engagement with the latch hook to move the hook relative to the door and release the door for dropping. The location of the point of engagement of the hook with the tripping arm above the lowermost portion of the car structure, particularly the end bumper structure, required another timing of this operation with respect to the movement of the car, so that the tripping arm would fall before it was engaged by the bumper. This timing was controlled also by the movement of the car which required that it function preferably under all conditions, with proper co-relation between the movement of the car and the operation of the tripping device.

One object of this invention is to simplify and improve the latch tripping mechanism to eliminate the mechanismal timing relation between the tripping arm and the movement of the car, and yet to provide for proper functioning of the tripping arm to effect the release of the latch hook in a positive manner and in proper position for dumping of the lading, and controlled entirely from a point inside the trackway. At the same time, the latch hook which holds the door closed is mounted at a point above the lowermost portion of the car in secure protected position without danger of the latch coming into contact with any obstructions in the track along the path of movement of the car which might improperly release the latch or cause damage thereto.

This is accomplished in the preferred form of the invention by locating the latch with its lowest portion above the lowest portion of the mine car structure in the same longitudinal vertical plane of the car, and mounting a tripping device at the desired point of dumping, which is so constructed as to cause release of the latch at this point without the necessity for perfect timing between the car and the tripping mechanism. This tripping mechanism includes a member movable in a general upward direction into the path of movement of the latch on the car, with means connected with said member and arranged laterally of said member for deflecting the member under the car into the space forwardly of the latch for engaging and tripping the latch to release the door for dumping. Inasmuch as this guiding means follows the contour of the under surface of the car, it will rise up into the space in which the latch is located at the proper point of tripping without the necessity for any particular timing relation between any actuating element on the car itself and the tripping mechanism.

In the preferred form of the invention, the tripping arm is mounted in the trackway in position for upward movement into the space above the lowermost portion of the car forwardly of the latch in position to engage the latch upon movement of the car along the trackway. This raising movement of the tripping arm is caused by a contact member connected therewith normally disposed yieldably in an elevated position above the point of engagement of the latch, and constructed so as to follow the contour of the under surface of the car until said space is reached, when the contact member allows thet tripping arm to rise up therein and cause release of the latch. This contact member, passing under the rear bumper structure, also lowers the tripping arm before it is engaged by the bumper, thereby passing under the rear portion of the car and allowing the car to continue thereover. Thus the tripping mechanism will cause an engagement of the face of the hook automatically whenever the hook reaches the point of clumping and without any necessity for a special actuating movement initiated by an element on the car itself, thereby materially simplifying the structure while improving the functioning of the tripping mechanism.

A further object of the invention is to improve the latch means that supports the free edge of the door for dropping, both in the manner of supporting the door and in its construction which will facilitate the release of the door by engagement of a tripping arm mounted in the trackway.

I have found that the free edge of the door should be supported, for best results, by at least two laterally spaced latches mounted for swinging movement longitudinally of the car and disposed as close to the opposite side structure of the car at the opposite edges of the dumping opening as is reasonably practical. These latch hooks should be located approximately 9 inches from the adjacent track gauge line, although this distance may vary slightly in transverse position from 7 to 10 inches from the adjacent track gauge line to the center of the hook. This center of the hook should be located 20.7% of the total door width from the adjacent side edge of the door, so as to sustain the maximum load without danger of sagging of the door between the spaced latches and without danger of bending of the door plate beyond its elastic limit, with the greatest factor of safety.

The hook is constructed also with a forward contact face so arranged with respect to the tripping arm that the forward movement of the car relative to the tripping mechanism will assure positive release of the latch before'the latter is moved far enough to be stopped by engagement with the end sill. I have found that the latch should move through an arc of at least 10, preferably 14, to accomplish this purpose. This prevents the premature depressing of the tripping arm before it has accomplished the effective release of the door for dumping.

I have shown different embodiments of this invention in the accompanying drawings in which:

Fig. 1 is a diagrammatic sectional view through a car showing the contact and tripping elements in different positions longitudinally relative thereto;

Fig. 2 is an endelevation of the car;

Fig. 3 is a side elevation of one form of tripping device and associated portion of the car, the main car structure being omitted to facilitate the disclosure;

Fig. 4 is a detailed'cross section therethrough on the line 4-4 of Fig. 3;

Fig. 5 is a detailed cross section therethrough on the line 5--5 of Fig. 3;

Fig. 6 is an end elevation of the tripping device, showing in dotted lines the relation of parts of the car thereto;

Fig. 7 is a side elevation of another form of tripping mechanism;

Fig. 8 is atop plan view thereof;

Fig. 9 is a front elevation thereof;

Fig. 10 is a side elevation of the tripping device modified to provide for the manual lowering of the contact elements; and

Fig. 11 is an end elevation thereof.

This invention is shown as applied to a mine car of the general type set forth in my prior patent, No. 2,001,471, granted May 14, 1935, adapted for conveying coal or other loose lading from a receiving point to a tipple or other point of discharge. The mine car is shown to be of the 4-wheel type, having three drop bottom doors interconnected for release in one-two-three order. This application of the invention is used however, merely for purpose of illustration, and it is evident that the subject-matter of this invention may be applied to other types of cars, vehicles, and drop bottom conveyors in general, Wherever it may be desirable to release bottom doors for dropping, in which the principles of this invention may be applicable.

The general structure of the car illustrated comprises a car body formed of side and end walls I and 2, rigidly secured together, the side walls I rising from a pair of oppositely disposed side sills 3 (Figs. 6 and 9), connected together at the ends of the car by means of combined end-sills and bumpers, designated generally at 4. The side and end-sills 3 and 4 comprise the frame structure of the car for supporting the lading body thereof, and between which is a bottom. opening 4 designated generally at 5 (Fig. 1) for discharge of the lading therethrough.

The car is supported upon wheels 6 and axles 7 connected with the side sills 3. The wheels 6 are adapted to travel on a track formed by a pair of rails indicated generally at R.

The car is shown of the character provided with three drop bottom doors adapted for discharge in one-two-three order from front to rear of the car. These doors are designated respectively by the numerals 8, 9 and it. The forward door 8 is pivotally supported at its forward edge on a hinge rod I I, while each of the middle and rearward doors 9 and I0 is slidably and pivotally mounted on a hinge rod I2 extending between the frame structures at opposite sides of the drop bottom opening 5.

The extreme forward edge of each of said doors 9 and 10, when in closed or latched position, projects laterally from the hinge rod !2, and is adapted to support the free edge of the next forward door. Then upon release of the rearward door, it may drop sufficiently to drag and move bodily rearward, thereby releasing the free edge of the middle door which will likewise drop and release the free edge of the forward door. This occurs usually just before the car reaches the tipple or bin, and permits dropping of the forward door in the bin for discharge of the lading thereon, as soon as room enough is provided in the bin therebeneath. The other doors drop in succession during the continued forward movement of the car over the bin or tipple in onetwo-three order from front to rear of the car.

After dumping in passing over the bin or tipple, the doors are adapted to be closed by the usual door-closing rails located in the track. The doors have indentations l3 in the under faces thereof to ride on the door-closing rails, which indentations extend transversely of the doors throughout substantial portions of the width thereof. The doors are thus moved successively about their hinge rods to their closed positions, and the middle and rearward doors are pushed forward into wedging relation with the next forward door, adapted to be latched in closed position.

The foregoing car structure, to which this invention is shown applied as hereinafter described, is set forth more in detail in my prior patents, No. 2,001,471, May 14, 1935, and No. 2,036,644, April 7, 1936, to which reference is made for a more complete illustration of the structure thereof.

As shown in Figs. 1, 3, 6, and 9, provision is made for latching the free edge of the rearward door It in closed position, thereby holding the several doors closed, to retain the lading in the car until the latching means is released for dumping. For this purpose, I have provided on the free edge of the rearward door It, one or more supporting trunnions M, one for each latch of said door. I prefer to use a pair of latches, each designated generally by the numeral 15 and spaced apart as indicated in Fig. 6, symmetrically with respect to the longitudinal center of the car. Each of the latches i5 is provided with a transverse engaging face It formed on a lateral flange thereon, as hereinafter described more in detail. The latches [5 are pivotally mounted on a cross shaft l'l supported by brackets l8 secured to the adjacent end wall 2 of the car. Each of the latches I 5 is preferably so constructed, or spring-pressed, as to be disposed nor- .mally in its door supporting position. or to return thereto automatically when dis-engaged for re-' lease of the lading.

Each of the latches I5 is provided with a concave seat it (Fig. 3) at the forward face thereof in position to receive the end of the adjacent trunnion E i attached to the free edge of the rearward door it. As shown in Fig. 3, the seat i9 is located on the opposite side of the vertical plane passing through the pivot axis of the latch it from the door lil, so that the weight of the door and the lading thereon tends to maintain the latched relation without any tendency for this weight to push the latch to one side. This is particularly true when the concave seat is engaged by a convex end of the trunnion, whereby any movement of the latch tending to release the door must raise up the free edge of the door.

Each of the latches I5 is provided preferably with a lateral pin 2t attached thereto and projecting through a slot in the adjacent portion of the end sill l (Figs. 2 and 3). A link 2| has one end connected with the pin 29 and extends upwardly therefrom through the top of the bumper structure The opposite end of the link 2!! is notched at 22, adapted to be engaged by a crow bar or other hand tool for manual release of the latch when this may be desirable.

The foregoing structure corresponds generally with that set forth in my prior application for Door Latch Mechanisms, Serial No. 432,341, filed February 25, 1942.

As shown in Figs. 1 and 3, the latches I5 are interposed between the free edge of the rearward door it and the adjacent end sill structure 4, underneath a guard plate 23 secured to the adjacent end wall 2. The latches [5 are so constructed and arranged that they are disposed wholly above the lower edges of the end sills of the car, and also, preferably, above the lower face of the rearward door, in protected positions. This prevents disarrangement of the latches or damage thereto in the event of wreckage of the car or from contact with obstructions in the traclzway, as might occur in a mine, thus assuring adequate protection of the latches to maintain these in proper operative positions.

Each latch i5 is so mounted in protected Dosition between the door Ill and the bumper 4 that a tripping space is provided between said door and the face it in latched position for entry of a tripping arm therebetween.

The tripping mechanism for the latches i5 is adapted for mounting in the trackway between the opposite rails R at a point adjacent the bin or other point of dumping. This tripping mechanism is mounted preferably on a dumping plate 2d (Figs. 3 and 6) having the the opposite edges thereof supported upon the base flanges of the opposite rails R. Where these rails are of large size, a filler 25 may be interposed beneath each side flange of the plate 24 between said flange and the rail flange, although for smaller rails the filler is not required inasmuch as the plate may be applied directly to these rails as indicated at R in Fig. 6. The plate 24 may be provided with skid bars 26 welded or otherwise rigidly to the upper surface and extending lengthwise thereof, as shown in Figs. 3 and 8 to support the dropped doors. The plate is braced by angle bars 2l extending transversely of the under side thereof adjacent opposite ends.

Secured to the under side of the dumping plate 2L1 adjacent opposite edges thereof are journal boxes 28 detachably mounted thereon by bolts 29 (Fig.- 6). A journal box' 30 is secured to the transverse center of the plate 24 by bolts 3|. The journal boxes 28 and 30 are in axial alignment with each other and form journals for aligned transverse shafts 32 which are independent of each other and relatively movable in the form shown in Figs. 3 to 6, where separate and independent latches are provided adjacent opposite sides of the door. Each shaft 32 has its outer end journaled in the box 28, and its inner end journalcd in the box 30. The adjacent ends of the shafts 32 in the box 30 are spaced apart normally as indicated in Fig. 6.

An arm 33 has a hub boss 34 welded or otherwise rigidly fixed to each of the shafts 32 at a point adjacent the lateral end of the center bearing box 33. The arm 33 extends upwardly from the shaft in an inclined direction, through a slot 35 in the plate 24. The upper end of the arm 33 carries a contact or guide member 36 welded or otherwise rigidly fixed thereon. This contact or guide member 36 is preferably of the shape shown generally in Fig. 3, being substantially of the form of an upstanding wedge with widely flaring sides. The contact member 36 has a web plate 31 fixed between the sides thereof to brace said member and insure substantial rigidity thereof.

Also mounted on each shaft 32 spaced outwardly from the contact arm 33, is a tripping arm 38, welded or otherwise rigidly fixed to the shaft 32, one tripping arm 38 being provided for each latch it. through a slot 39 in the plate 24 and is arranged parallel with the contact arm 33. Thus the contact arm 33 is directly behind the tripping arm 38, as viewed in Fig. 3, and, substantially, coextensive in length and size with said tripping arm, although carrying the contact member 36 directly on the upper end of said contact arm. However, the shape of these arms may be varied as found desirable. The upper end of the tripping arm 38 has fixed thereto a head member or portion 4%) adapted to engage the contact face Id of the flanged portion on the adjacent latch A limit arm M is fixed also, by welding or otherwise, to each shaft 32 in lateral abutting relation against the adjacent tripping arm 38 and preferably welded at the respective intersecting edges to said tripping arm to be rigid therewith. The limit arm 4| extends horizontally from the shaft 32, as shown in Fig. 3, for the purpose of controlling the up and down swinging movement of the arms 33 and 38.

Welded to one side of the limit arm 4|, adjacent the outer end thereof, is an abutment 42, in position to engage the lower end of a limit screw 43, which is screw-threaded through the dumping plate 24 and through a nut member 44 fixed thereto, as shown in Figs. 3 and 4. The limit screw t3 may be adjusted up and down with respect to the plate 24, and locked in its adjusted position by a jam nut 45. When the abutment 52 engages the lower end of the limit screw 43, it prevents further upward movement of the limit arm ti, and thereby prevents further upward movement of the contact or guide member 36, as well as the tripping head 40, carried on the respective arms 33 and 38.

These parts are held yieldably in elevated positions by a coiled spring 46 which is sleeved over a bolt 47, as shown in Figs. 3 and 5. The bolt it extends upwardly through the dumping plate 24 by which it is supported. The bolt 41 also extends through a guide member 48 mounted The tripping arm 38 extends upwardly on the limit arm 4|. The spring 46: has one end thereof abutting against the under side of the guide member 48 while the opposite end of said spring bears upon a washer 49 confined by nuts 50 threaded on the lower end of the bolt 41. The tension of the spring 46 may be varied by adjusting the nuts 50.

The spring 46 normally is of sufiicient tension to support the weight of the arms 33 and 38 and of the contact member 36 and tripping head 40 carried thereby, so as to hold these parts in elevated positions, and with the contact member 36 somewhat above the point of contact of the tripping head 40 with the face 16, but yieldable for depressing action upon engagement of the contact member 36 by the bottom contour of the car as the latter passes over the tripping mechanism.

The under surface of the car is fairly smooth and regular; such rigid abutments as are present at the points where the contact members 36 engage the under surface portion of the car, are such that the contact members pass under the same. The manner in which these contact mem bers will follow along the under surface of the car is illustrated in the several dotted line positions in Fig. 1, designated respectively Cl, C2, C3, and finally, in full lines, the position of the contact member 36 in the tripped position of the latch, which latter is indicated also in clotted linm in Fig. 3.

It will be evident that a horizontal space is provided between the rear edge portion of the rearward door Iil and the forward face of the rear bumper structure 4, in which space the latches it are disposed, with their contact faces I6 entirely above the lower edge of the end sill, as well as above the lowermost portion of the bottom door plate. The tripping head all must be raised by the tension of the spring 46 into this space in properly timed relation to engage the contact face [6 of each latch if: in its latched position, as shown in full lines in Fig. 3.

This is made possible by the shape and character of the contact or guide member 36 which will be forced up in this space sufficient to allow such engagement of the head id with the face iii of the latch member. The tilting of the device, so that the face 40 will engage properly the face [6 of the latch member, can be controlled also to some extent by the tension of the spring 46. The bend in the plate of the bottom door It? can be made rather sharp if the tension of the spring 46 is sufficient, but it is preferred to keep this tension as low as possible to avoid undue wear between the contact member 36 and the bottom of the car structure. Nevertheless, the tension should be sufiicient, so that the tripping head 43 properly contacts the latch face 16, even at the maximum speed at which the car may be moved over the dumping bin.

Then upon forward movement of the car relative to this tripping mechanism, the latch I will be forced from its full-line to its dottedline position in Fig. 3, releasing the supported trunnion 14 on the rearward door it and allowing said rearward door to drop to dump the lading as described above. It will be understood that both latches, if two are used, as in the preferred embodiment, will be released approximately simultaneously by the respective tripping heads 45, even though each tripping element acts independently of the other under the controlling influence of its element 36.

After thus moving the latch 15 during the forward movement of the car, it is necessary that 8 the tripping head 40 be depressed before the forward face of the end sill 4 reaches said tripping head. However, it will be evident from Fig. 3 that the adjacent side of the contact member 36 projects outwardly beyond the tripping head sufficiently so that it will contact the forward edge portion of the end sill before said edge portion will engage the tripping head. Therefore, the contact member 36 will be depressed by such engagement with the end sill, and as it moves down and under the end sill, it will carry with it to a lowered position the upper end portion of the tripping arm 38 and its tripping head 40.

These parts will thus be depressed as the car rides over the contact member 36, and since the tripping arm can never rise higher than the upper portion of the contact member, it will not engage any part of the car until it is reached by the latch IS in the same longitudinal vertical plane therewith. The car is so constructed with the structural parts thereof extending transversely that any part in the upright plane of the tripping arm 38 would also extend transversely across the upright plane of the contact arm 33. Therefore, such part would be engaged first by the contact member 36 as the latter is guided under the car during movement of the latter over the tripping mechanism, as indicated in Fig. 1. Nevertheless, this action will insure the raising of the tripping arm in properly timed relation for engagement with the latch 15 to release the latch for tripping.

To insure that a tripping of the latch will actually occur, without merely a depressing of the tripping arm, I have found that a definite relation should be maintained between the engaging faces of the tripping head 40 and the latch 15, as is indicated in Fig. 3.

It will be evident from Fig. 6, as described above, to provide a separate tripping arm with its connected contact member on each opposite side of the car, each tripping arm being adapted to release the corresponding latch; and these latches are symmetrically arranged on the car as described above. This insures proper actuation of the respective latches regardless of slueing of the front end of the car on a loose track gauge which might otherwise dispose one of the latches slightly forwardly of the other, whereby it would engage and release the tripping arm in advance of the engagement and release of the other tripping arm by the other latch.

Not only this, but the time of contact of the tripping arms with the respective latches would vary when the car is slued, so that one of the latches may fail to release, which would leave the door latched against dropping, unless the track is securely mounted at the point of dumping so as to prevent such slueing.

The separate and independent unlatching of the latch hooks also insures the satisfactory unlatching of both hooks when inaccurate shop practice has the effect of making one of the contact members come into contact with its latch hook before the other contact member is in engagement with its latch hook. If only one of the latch hooks should be released, the door would bend sufficiently on that side to permit the trunnion l4 (Fig. 3) to drop to a point where it would not be re-latched by the latch hook thereafter until the door has been raised to a higher than normal position. In other words, if the two unlatching mechanisms were so spaced, one hook would be forced into its unlatched position before the other and the latter would not be released until the car has travelled further along the trackway.

It is also practical under some circumstances to provide for the joint actuation of both tripping arms mounted on a single shaft, as shown in Figs. 7 to 9.

In this form of the invention, the dumping plate 6i substantially corresponding with the plate 24 described above, extends transversely between the track rails as described above. Journaled in transversely spaced bearing boxes 62 on the under side of the plate BI is a cross shaft 68 which extends continuously transversely throughout substantially the entire width of the dumping plate.

Approximately midway of the length of the shaft 63 is fixed thereon a contact arm E i extending forwardly and upwardly therefrom as shown in Fig. 7. The outer end of the arm it carries a contact or guide member 65, which corresponds in shape and operation with the contact member 38 described above, said contact member and arm 64 operating through a slot 56 in the dumping plate 6|. As shown in Fig. 8, the contact member 65 is approximately midway between the opposite edges of the dumping plate i and, therefore, midway of the width of the car travelling on the track rails.

Spaced outwardly on opposite sides of the contact arm 64 are tripping arms 61 each of which is fixed rigidly by welding or otherwise to the cross shaft 63, and extends upwardly through a slot 68 in the dumping plate 6|, having a somewhat widened tripping head 68 on the forward end thereof for engaging and actuating the corresponding latch.

Each of the tripping arms 51 has a lateral bracket in fixed thereto intermediate the length of said arm and projecting laterally therefrom, as shown in Fig. 8, the opposite end of which bracket is is welded or otherwise secured to a short arm II, which short arm H is welded or otherwise fixed to the cross shaft 63. A second short arm 2 is spaced laterally from the short arm II and is loosely pivoted on the cross shaft 83. Interposed between the short arms H and i2 is a coiled spring 73 sleeved over a bolt 74 and confined by clips 15 and 16 secured respectively to the arms II and 72. Thus a yieldable connection is provided between the arms H and '52 for actuating the tripping arm 61.

J ournaled on the cross shaft 63 beside the arm 72 is a bracket member I! which is adjustable relative to the arm H by adjusting screws 18 interposed therebetween. The bracket member ll may be provided, if desired, with an upstanding casting 38 for actuation of the tripping mechanism by means of a projection on the car, if desired, in the manner set forth in my prior application for Door Latch Mechanisms, Ser. No. 432,341.

Also fixed to the bracket member i1 is a weight arm is from the outer end of which a weight may be suspended in the event that the casting I3 is to be used for operating the tripping mechanism, to maintain these parts in proper operative positions, as explained more fully in my prior application referred to above.

When the latch tripping mechanism is to be operated by the contact member 55, the arms M 6? should be held in elevated positions sm-.ciently high so that the tripping arm 5'! will always rise up to the point of engagement with the latch as indicated by dotted lines in Fig. I have shown a series of springs 80 for this purpose, sleeved over a bolt 8| suspended from the dumping plate BI. The arm 61 has a bracket 82 bearing upon the upper end of the series of springs while the lower end thereof is confined by a washer 83 and adjusting nuts 84 to vary the tension of the springs. The springs normally are adjusted so as to hold the parts in the dotted-line positions in Fig. '7, but will yield to allow depression thereof to the full-line positions therein, when a car passes over the tripping mechanism.

The upward swinging movement of the arm 61 may be controlled by a limit screw 85 threaded through the dumping plate GI, and adjustable in the path of movement of the tripping arm 61.

Otherwise than as indicated above, this form of tripping mechanism functions substantially in the same manner as described above in connection with Figs. 1 to 6. However, the latches will be released by the simultaneous actuation of the tripping arms on both opposite sides of the car, both of which arms will be operated by a single contact member disposed midway of the width of the car. This is somewhat simpler in structure than the form shown in Figs. 1 to 6 and will be entirely practical for use in many applications.

The outer end of the cross shaft supporting the contact and tripping arms may be squared or otherwise fashioned, if desired, to receive thereon a wrench or lever for manual turning of said shaft to lower the contact arms when desired. This may be desirable when passing a mine locomotive over the tripping mechanism or when passing cars thereover without unlatching the doors.

In Figs. 10 and 11, I have shown the contact device corresponding substantially with that shown in Figs. 3 to 6, but provided with mechanism for lowering the tripping arms and contact members to clear cars and locomotives passing thereover, and to allow cars to pass without tripping. In this form, the cross shaft 32' is extended beyond the bearings 28 sufficiently to be provided thereon with arms 86 which are connected by a chain 81 with depending arms 86' carried by an extended roller bar 88 extending transversely of the bearing plate 24 and journaled thereon in hanger brackets 88. The outer end of the roller bar 88 has an upstanding hand lever 89 for turning said bar, and located sufiiciently far removed from the side of the trackway as not to interfere with the mine cars passing over said trackway.

It will be evident that the swinging motion of the hand lever 89 manually, in Fig. 10, will rotate the roller bar 88 to cause a lateral pull on the chains 8'! extending between the arms 86, 86, thus forcing downward the tripping arms and contact arms against the tension of the springs acting thereagainst. The parts may be held in these lowered positions until the car or locomotive passes thereover and then upon release of the hand lever 89, these parts will be returned to their operative positions. It is thus possible to allow the cars to pass over the bin in reverse direction, without engagement of the contact devices, or the cars can be dumped selectively by lowering the contact devices when certain predetermined cars are passing thereover that will allow their doors to remain latched.

I have found that the latches which support the free edge of the rearward door l0 preferably should be spaced apart not only symmetrically with respect to the transverse width of the door, but that they should be located in particular relation to the adjacent track gauge line. The latch hooks should be mounted in such position that the center of each hook would be spaced 20.7% of the total door width from the adjacent side edge of the door, so as to sustain the maximum load without danger of sagging of the door between the spaced latches and without danger of bending of the door plate beyond its elastic limit with the greatest factor of safety. Ordinarily this distance would be nine inches from the center of the hook to the adjacent track gauge line, although this distance may vary somewhat depending upon the thickness of the latch hooks, from approximately 7 /2 to 10%.; inches.

I claim:

1. Latch tripping mechanism adapted to be mounted in a trackway for releasing a drop bottom door of a conveyance thereon, said mechanism comprising latch release means, a shaft, an arm fixed to the shaft and extending upwardly therefrom supporting the latch release means thereon for raising movement of said means into latch release position and for lowering movement therefrom, a second arm fixed to the shaft beside the first-mentioned arm and spaced laterally therefrom, and a contact member on the second arm and located at substantially the same elevation as the latch release means when the latch release means is in latch release position, and means connected with the shaft normally urging the arms upwardly.

2. Latch tripping mechanism adapted to be mounted in a trackway for releasing a drop bottom door of a conveyance thereon, said mech anism comprising latch release means, a shaft fixed to said latch release means for raising movement into latch release position and for lowering movement therefrom, an arm fixed to the shaft and extending upwardly therefrom, a contact member on the arm and located at substantially the same elevation as said latch release means when said latch release means is in latch release position, a track plate supporting the shaft below the plate and having an opening therein with the arm projecting upwardly therethrough, an arm fixed to the shaft and extending laterally therefrom beneath the track plate, an anchor member fixed to the track plate, and spring means interposed between the last-mentioned arm and the anchor member normally urging the latch release means to said latch release position.

3. Latch tripping mechanism adapted to be mounted in a trackway for releasing a drop hot-- tom door of a conveyance thereon, said mech anism comprising a shaft, a pair of separate arms fixed on the shaft in side-by-side spaced substantiaily parallel relation and extending upwardly therefrom, one of said arms having an offset end portion in position for engagement with the latch, a contact member on the other arm and located at substantially the same elevation as the ofiset end portion when said portion is in latch release position, and means for yieldably urging said arms upwardly.

4. Latch tripping mechanism as defined in claim 3, including a track plate adapted to extend between a pair of spaced rails, and means mounting the shaft on the track plate for upward swinging movement of the arms relative thereto.

5. In conveying mechanism, the combination with a trackway including a pair of spaced rails, of latch tripping mechanism adapted for releasing a drop bottom door of a conveyance thereon, comprising a track; plate extending in bridging relation between the rails and supported at opposite sides thereby, a shaft supported on the track plate, a pair of separate arms fixed on the shaft in side-by-side spaced substantially parallel relation and extending upwardly therefrom, one of the arms having an offset end portion in position for engagement with the latch, a contact member on the other arm and located at substantially the same elevation as the offset end portion when said portion is in latch release position, and means for yieldably urging said arms upwardly.

6. Latch tripping mechanism as defined in claim 3, wherein said contact member extends lengthwise of said other arm and has opposite end portions downwardly inclined from an intermediate portion thereof located at substantially the same elevation as the offset end portion of the first-mentioned arm.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Publication: Mining Congress Journal, 1944, pages 2 and 3.

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