US2659500A

US2659500A - Rotary car dumper

Info

Publication number: US2659500A
Application number: US97258A
Authority: US
Inventors: John H Kincaid
Original assignee: WELLMAN ENGINEERING Co
Current assignee: WELLMAN ENGINEERING Co
Priority date: 1949-06-04
Filing date: 1949-06-04
Publication date: 1953-11-17
Anticipated expiration: 1970-11-17

Description

NOV. 17, 1953 K|NA|D 2,659,500

ROTARY CAR DUMPEIR Filed June 4, 1949 7 Sheets-Sheet l JNVENTOR. J/l/v K/NCA/p Ar NEYS Nov. 17, 1953 J. H. KlNCAlD ROTARY CAR DUMPER 7 Sheets-Sheet 2 Filed June 4, 1949 nah JNVEN TOR. J/w' AK Km/cA /0 fie. 2

Nov. 17, 1953 J. H. KlNCAlD ROTARY CAR DUMPER Filed June 4, 1949 '7 Sheets-Sheet 3 INVEN TOR. J O/I/Y KmcA/o 1M; a mu), Ar wan/5y:

Nov. 17, 1953 J. H. KINCAID ROTARY CAR DUMPER 7 Sheets-Sheet 4 Filed June 4, 1949 INVENTOR. J'w/N A- Am'cA/o M, QM;

Arrae/VEYS Nov. 17, 1953 J. H. KlNCAlD 2,659,500

ROTARY CAR DUMPER Filed June 4, 1949 7 Sheets-Sheet 5 fia. 5

INVENTOR.

Jaw/v A. K/NcAlo Arne/vs Y5 Nov. 17, 953 J. H. KINCAID 2,659,500

ROTARY CAR DUMPER Filed June 4, 1949 7 Sheets-Sheet e INVENTOR. Jaw/v A! /\//NC4/D NOV. 17, 1953 H, K Nc m 2,659,500

ROTARY CAR DUMPER Filed June 4, 1949 7 Sheets-Sheet '7 fie. 7

fia- 6 fie. 9

I N V EN TOR.

Arr RNEYS Patented Nov. 17, 1953 UNITED STATES ATENT OFFICE ROTARY CAR BUMPER Application June 4, 1949, Serial No. 97,258

3 Claims. (01. 214-55) The present invention relates to rotary car dumpers adapted to unload railway cars by inverting the same and, more particularly, to mechanisms for holding the cars in the dumpers while they are inverted.

One type of car dumper to which the present invention relates comprises a cradle rotatable on its longitudinal axis and provided with a platen having rails for receiving a railway car. The cradle includes clamps which are movable into and out of engagement with the top of a car positioned in the cradle for holding the car to the rails when the cradle is rotated and the car inverted. Heretofore it has been proposed to maintain the clamps in engagement with the car by counterweights which urge the clamps toward the car as the cradle is inverted with sufficient force to hold an empty car to the rails. One difiiculty with this arrangement has been that when the load in the car fails to discharge, the combined weight of the car and load overcomes the counterweights and causes the car to leave the rails. It has also been proposed to positively lock the clamps in position against the car body by latching mechanisms which include ratchet teeth and latching pawls adapted to engage with the teeth. In some instances the pawls initially engage the ratchet teeth in a non-latching relationship which causes the clamps to yield as the weight of the car is applied thereto and move to a position in which the pawls latch with the ratchet teeth. In this event and in the event that the carriage springs of the railway car have lost all or a large part of their original resiliency, there may not be sufiicient pressure between the car body and its springs, when the car is inverted, to hold the springs in place and the latter are apt to become displaced.

One of the principal objects of the invention is the provision of a new and improved car dumper comprising a rotary cradle having a platen adapted to receive a railway car, a car clamp movable when the cradle is rotated into engagement with the top of the car, and holddown mechanism for the clamp including a counterweight effective, as the cradle rotates to dump the car, to urge the clamps against the car, and a ratchet and pawl device for connecting and releasing the counterweight from the clamp.

Another object of the present invention is the provision of a new and improved car dumper comprising a rotary cradle having a platen adapted to receive a railway car, a car clamp movable when the cradle is rotated into engagement with the top of the car, and holddown mechanism for the clamp including a ratchet device having a ratchet element and a pawl element engaged and disengaged when the cradle is rotated to and from the car inverting position, respectively. The ratchet device also includes a counterweight connected with a ratchet or the pawl element and operative to urge the element in a direction to press the clamp against the car and hold the car tothe platen while the cradle is inverted.

Another object of the invention is the provision of a car dumper of the character referred to in the preceding paragraph in which the pawl element of the ratchet device is connected with a lever rotated by a counterweight to urge the pawl in a direction to force the clamp against the car and hold the latter to the platen when the cradle is inverted.

Still another object of the invention is the provision of a new and improved car dumper comprising a rotary cradle having a platen for receiving a car therein, a clamp having a series of ratchet teeth thereon and movable into engagement with the car in the cradle to maintain the car against the platen when the cradle is inverted, a pawl engageable with the ratchet teeth for locking the clamp in engagement with the car and movable for accommodating itself to latchingly engage with a tooth on the clamp when the clamp is engaged with the car, and means for urging the pawl in a direction and with sufficient force to maintain compression of the car springs through the clamp and car body.

The invention resides in certain constructions and combinations and arrangements of parts and further objects and advantages will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment described with reference to the accompanying drawings forming a part of this specification, in which:

Fig. 1 is a side elevational View of a part of a car dumper embodying the present invention;

Fig. 2 is an end elevational view of the car dumper shown in Fig. 1;

Fig. 3 is a sectional View taken substantially along line 3-3 of Fig. 1;

Fig. 4 is a view similar to that of Fig. 3 but showing the cradle of the car dumper in a substantially inverted, car dumping position;

Fig. 5 is a sectional View taken substantially along line 55 of Fig. 8, and showing the hold down mechanism for one of the car clamps of the dumper;

Fig. 6 is a view similar to that of Fig. 5 but howing the parts of the holddown mechanism in 3 the positions assumed when the cradle of the car dumper is substantially inverted;

Fig. '7 is a sectional view taken substantially along line '!--'I of Fig. 5;

Fig. 8 is a sectional view taken substantially along line 88 of Fig. 5; and,

Fig. 9 is a sectional view taken substantially along line 99 of Fig. 5.

In general, the invention contemplates a rotary cradle having a platen adapted to receive a railway car thereon, clamps movable into and out of engagement with the top of the railway car on the platen to hold the car to th platen as the cradle is rotated to invert the car and dump the load therefrom, and a clamp holddown mechanism for one or more of the clamps comprising a pawl and ratchet engageable with one another and having limited movement while engaged in a direction to move the clamp associatedtherewith against the car, in combination with a counterweight mechanism or its equivalent acting upon the pawl or ratchet to force the clamp against the car and hold the car to the platen when the cradle is rotated to invert a car.

Referring to the accompanying drawings, the rotary car dumper shown includes a cradle 18 adapted to receive a railway car C therein, which car is indicated by broken lines. The cradle is supported on a suitable base H in such manner that it can be rotated about a longitudinal axis to dump the contents of the car into any desirable type of receiver, not shown, below the cradle. The cradle comprises a frame [2 generally U- shaped in cross section and closed at the sides by plates l3. Alternatively the plates It may be omitted and the sides left open. The frame also includes circular end structures M, 5, which structures have generally rectangular openings through which railway cars may enter and leave the dumper. The end structures l4, [5 have circumferential tracks I6, I! which ride on sets of flanged rollers l8, [9, respectively, journalled on the base ll, whereby the cradle may be rotated about an axis normal to the plane of the end structures. Any suitable power mechanism may be utilized for rotating the cradle, and as such mechanism is well known, it is not shown.

The cradle includes a platen 20 having rails 2| supported thereon, which rails are adapted to align with a railway 22 which leads to and from the respective ends of the dumper so that railway cars may be received into the cradle atone end and removed at the opposite end. It will be understood, however, that the cars could enter and exit from the same end of the cradle, if desired. The platen 28 is arranged in the cradle for lateral movement so that when the cradle is rotated clockwise, as viewed in Fig. 2, to invert the car, the platen moves to the right to bring the right-hand side of the car into engagement with abutments 23 at the side of the cradle, as seen in Fig. 4. When the cradle returns to the position shown in Fig. 2, the platen is automatically moved to bring rails 21 into registration with the railway 22. Mechanisms for moving the platen in the manner described are well known in the art and, therefore, the details of such mechanism are not shown.

Clamps for holding the car to the rails 2| while the cradle is rotated are indicated at 25, 26, 21.

Clamps

25, 26 are located at the right-hand side of the cradle, as viewed in Fig. 2, and clamp 21 is located on the opposite side of the cradle. The weight of the car bears predominantly against the clamps on the side of the cradle from which the car is emptied and this side of the cradle is provided with a greater number of clamps. Preferably, there are four clamps on the righthand side of the cradle, although only two appear on the drawings, and two clamps, one of which is shown at 27, on the opposite side of the cradle. The drawings show but one half of the car dumper and the other half is identical with the half shown and the various parts thereof are arranged symmetrical with those shown.

All of the clamps are of the same general construction and each comprises a shank S having a car-engaging member M extending laterally from the upper end of the shank and inwardly relative to the cradle. The shanks of the clamps slide in vertical guideways on the cradle, as viewed in Fig. 1, to move the members M into and out of engagement with the top edges of the car body.

Referring to Fig. 8, the shank for clamp 28 and its guideway is shown in cross section. The guideway comprises two parallel guide strips 28, 29 which extend along the inside of wall plate [3 and which are backed by flanges of channel members 38, 3!, respectively, which channel members comprise uprights of the cradle frame [2. Preferably, the guide strips each has a raised portion along one edge on which a part of the clamp shank may slide. Two sets of oppositely disposed

guide brackets

34, 35 are attached to the

strips

23, 29, respectively, by bolts 35, 3] which extend through the flanges of the channels 38, 3 I. Each guide bracket has an undercut portion 38 along one edge'which forms a channel for receiving a flange on the shank of the clamp. The sets of brackets are suitably spaced along the guide strips to hold the clamp shanks to the guide strips.

The shank of clamp 26 is formed by a tubular structure rectangular in cross section and which comprises plates 4-0, 4!, 42, 43, suitably joined together, as by welding, and plate 43 has a series of ratchet teeth 44 formed along the outer surface thereof. Plates 46, 22 have out-turned flanges 5, 48 which are adapted to extend into th channels formed by the undercut portions 38 of

brackets

34, 35 and to slidingly engage guide strips 28, 29. The teeth 44 slope upwardly, as seen in Fig. 5, and present latching surfaces which face upwardly and outwardly of the clamp shank. A section of the side plate [3 intermediate the channel members 30, 3| is open whereby the teeth 34 may be engaged by a pawl positioned intermediate th channel members 38, 3|.

The structures of the clamp shanks and guideways for all of the clamps on the cradle are preferably like those described with reference to clamp 26 and, for the sake of clarity, they have not been shown or described in detail.

The clamps 25, 26 are adapted to be lowered by gravity into engagement with the top of the car body as the cradle commences to rotate to dump the car and to be raised from the car as the cradle rotates in the opposite direction following the dumping of the car. Clamp 25 is raised and lowered by a cable 5!] wound on a drum 5: which is rotated by a cable 52 on a drum 53, which is formed integral with drum 5!. Cable 52 is connected to one end of a lever 56 through suitable sheaves, which lever is pivotally connected by a pin 51 to a bracket 58 carried by the cradle. When the lever 56 is in the position shown in Fig. 2, the cable 52 maintains the clamp 25 in its elevated position, as shown. When the lever 56 is permitted to rotate counterclockwise, cable 52 plays out and allows clamp 25 to be lowered by gravity until it engages the top edge of the car. The left-hand end of lever 56, as viewed in 2, has a curved surface 59 which is adapted to engage a roller 69 journalled in a bracket 6i on the base ii. As the cradle rotates clockwise from the position shown in Fig. 2, the lever 56 is carri d to the left of roller 60 and the weight of the clamp rotates the lever counterclockwise. A tension spring 62 is connected to lever 56 and tends to rotate the lever clockwise and maintain the cable 52 taut. When the cradle rotates counterclockwise from the car dumping position the curved surface 59 engages roller 69 and moves the lever 56 clockwise to draw the cable 52 and rotate

drums

51, 53 to raise the clamp 25 by cahis 56.

The clamp 26 is raised and lowered by like mechanism, corresponding elements of which are designated by like reference numerals bearing a prime. Clamps corresponding to clamps Z6 and located on the half of the dumper, not shown, are operated by corresponding mechanisms, none of which appear in the drawings.

Clamp 2i and its companion clamp, not shown, may be moved into and out of engagement with the car by suitable mechanisms. In the embodiment shown, the cable for raising the clamp 2'! is connected to the lever 56 which operates the ciamp 26.

Each of the car clamps may have individual holddown mechanisms, however, only the holddown mechanism associated with clamp 26 is herein shown and described in detail. As shown, the holddown mechanism for clamp 26 includes pivoted pawl 64, the pivot of which has limited, translational movement whereby the pawl, acting through the ratchet with which it cooperates, may urge the clamp against the car to hold the car to the platen. A counterweight mechais arranged to urge the pivot of the pawl a direction to force the clamp against the car as the cradle is inverted. The pawl 64 is suspended from a lever 65 by a link 66, one end of which link is pivotally attached to the pawl 66 by a pin 6?. The other end of the link 66 has an elongated opening 66 therethrough, through which a pin 69 extends for pivotally supporting the link on the lever 65 through a lost-motion connection. One end of the lever 65 is forked and jcurnalled between the channel members S6, 35 by a pin it. The pin 69 is supported between the tines of the forked lever 65 and when the lever is rotated on the pin '56, the pawl 64 is moved generally in the direction of movement of the shank of the clamp 26 along its guideway.

The lever 65 is urgd counterclockwise by two tension springs '52, it which are attached at one end to a bar 'M on the lever and at the other end to a bracket on the channel members 39, 3!, and the lever is normally held against a stop bar 75 attached to two parallel frame members iii. The outer end of the lever 65 is connected to a cable i1, which is attached to a counterweight i'e arranged to move the lever clockwise against the action of the tension springs 12, 13 when the cradle is rotated toward the car inverting position.

pawl 6 is supported between two plates 69, 8!, which are riveted or welded to the link 66 by bearing formations 6 3 thereon which are journalled in openings in the plates. The pawl includes a broad, forwardly projecting, toe portion 66 which is shaped to latchingly engage with the upturned surfaces of teeth 4-1 of the clamp shank, and two rearwardly extending webs 88,

89. The pawl is adapted to swing between the plates 89, 8| on the bearings 84 and the swinging movement is limited by pairs of

stops

90, 9| formed on the webs 88, 89. The stops 9!], 9| engage opposite sides of projections 93, only one of which appears in the drawings, on the side plates 8!), iii. The pawl is urged to a position in which stops 9:) engage the projections 93 by a spring 94 which is attached at one end to a bracket 95 formed on the pawl member and at the opposite end to a bracket 96.

The pawl 64 is adapted to be swung to and from the teeth 44 by pendulums I00, H which are connected to the ends of a shaft I02 journalled in brackets I03, I04, which are attached to the

channel members

30, 35 by the bolts 36, 31. The shaft I02 has a pair of lugs I06 formed thereon and a connecting rod I6! is pivotally connected with the lugs by a pin I08 which extends through an opening in one end of the connecting rod. The opposite end of the connecting rod is threaded into an opening in a block [69 which is pivotally connected with the plates 89, 6! of the member 66 by a pin Hi), the ends of which are journalled in openings in bosses formed on the plates. The bracket 96 to which the spring 96 is attached is supported on the connecting rod i6! and a nut Hi threaded on the connecting rod I91 secures the bracket 96 to the member 169. When the cradle rotates clockwise from the position shown in Fig. 2, the pendulums I66, iill cause relative movement between the shaft itZ and the cradle, which swings the pawl 65 toward the ratchet teeth 44 of the ciamp shank to bring the toe 86 of the pawl into latching engagement with the teeth. Conversely, as the cradle rotates from the position shown in Fig. 4 counterclockwise, the pendulums tend to draw the pawl from engagement with the ratchet teeth.

The stops 90, 9! which limit pivotal movement of pawl ea relative to the two side plates 66, 8| are positioned such that when the toe 86 latchingly engages with a tooth 44 of the clamp shank and pressure is applied to the pawl through the lever 65 moving clockwise, the center line of force is substantially a straight line through the axis of the pins 69, 6? and the toe 86 of the pawl 64 and the projections 96 are in engagement with the stops 99, as seen in Fig. 6. The lever 65 may then impart force to the clamp through the pawl 64 and one of the teeth at and yieldingly urge the clamp 26 toward the platen of the cradle. The construction of the pawl 64, links 66, etc., is that of a toggle and because of the fact that the

pins

67, 69 and the toe 86 of the pawl 64 are substantially in a straight line, along which line the clamping pressure is applied, very little force is necessary to hold the parts in the positions shown in Fig. 6 and this can be readily accomplished by the relatively small pendulums R90, l9i. Because of the same construction, the pawl 64 can be readily released and disengaged from the ratchet tooth with which it is in contact when the dumper is rotated in the reverse direction. When the dumper reaches a predetermined position in its reverse movement, the action of the pendulums I69, 19! is reversed and their weight, although relatively small, readily moves the axis of the pivot 61 in a direction away from the ratchet until the projections e3 engage the stops 9!. This action has been referred to in a copending application of Robert W. Crist, Serial No. 648,461, now Patent No. 2,479,816 as a 7 knuckling out action, where it is described and claimed.

Continued movement of the link 66 under the pressure of the pendulums I00, I01 withdraws the pawl E 2 fromthe ratchet teeth. tothe position shown in Fig. 5. The pawl 64 and. link 66 are held in the relative position shown with respect to each other by the spring 94. The'slo't 68 in the link 66 provides a lost motion connection which compensates for the increased normal height of the car after its load has been removed, in the event that the other parts of the holddown mechanism are so constructed that, except for this lost motion, the pawl 64 would be under considerable pressure and the pendulums I00, It! not heavy enough to withdraw the pawl 64 from the ratchet teeth at the proper time.

The counterweight 78 which is connected with lever 65 through the cable i! has guide wheels H4 attached thereon which are supported between the fianges of two parallel channel members i ii, only one of which appears in the drawings. The channel members H5 are supported on the cradle structure and disposed in such angular position that the counterweight moves therea-long by gravity to operate the lever 65 clockwise after the cradle 52 has moved through approximately SO toward the car inverting position. As the cradle approaches the limit of its car inverting rotation, substantially the entire mass of the counterweight i8 is effective to act on the lever 65. Usually more than one clamp, similar to clamp 26, is utilized on a single car dumper, the masses of the counterweights corresponding to counterweight it being so proportioned that as an aggregate, they will produce a total force on the clamps associated therewith sufiicient to hold the car firmly against the rails as the car is inverted, although individually the counterweights may not be sufiiciently heavy for this function.

In the present embodiment, only the clamp 26 and the clamp symmetrical therewith on the other half of the dumper, not shown, are provided with the holddown mechanism shown and just described. The other clamps are provided with holddown mechanisms similar to that shown and claimed in the aforesaid patent; however, it is to be understood that the holddown mechanism employed with clamp 26 may be used with all or any numbers of the clamps, if desired.

The operation of the car dumper is as follows:

A railway car is moved into the cradle !2 on the rails 2i and the cradle is then caused to rotate clockwise. As the rotation proceeds, the car clamps including the

clamps

25, 26, 2'5,

descend and engage the top edges of the car body Upon continued rotation of the dumper, the pawls associated with the respective clamp are subsequently swung into engagement with the ratchet teeth on the clamp shanks to lock the clamps in position against the car body. Referring to the clam 23, the lever 55 is then moved clockwise, as viewed in Fig. 5, by the counterweight 18' connected thereto and if the pawl 66 has failed to initially latch with one of the teeth 44 due to misalignment, the pivot or" the pawl is translated by the lever 65 to move the toe of the pawl into latching engagement with one of the teeth. Continued movement of the lever after latching engagement of the pawl with a ratchet tooth, tends to cause the pawl to buckle relative to the plates 80, 8!, however, the pendulum weights associated with the pawl maintain the projections 93 in contact with the stops at and the pivot 69 substantially in line with the pivot 6'! and the toe 86 of the pawl 64 and toggles or knuckles the pawl into locking engagement with the ratchet tooth. Continued rotation of the cradle causes counterweight: 13 to increase the pressure exerted on lever to urge the car clamp 26 toward the platen of the cradle and hold the car body against the. carriage springs of the car and the wheels of the car against the rails of the platen. As the load is emptied from the inverted car, the car clamps may tend to move the car body upwardly to maintain a substantial compression on the carriage springs and retain the springs in assembled relation in the car.

In the event the load should stick inside the car for any reason, such as freezing, the car clamps positively lock the car in the cradle. Movement of the clamp 26 under the weight of the car and load, in the event the construction of the other clamps is such as to permit the clamp 26 to move under the weight of the car and load against the action of its counterweight, is positively limited by engagement of the lever 65 with the stop bar i5 so that the car is prevented from leaving the rails in any case.

After the car is emptied, the cradle is rotated counterclockwise to the upright position, during which movement springs 12, '13 cause lever 65 to move against stop Z5 as the counterweight l8 releases its pressure on the lever. The pendulurns Nil, i9] draw the latch member 66 from the teeth 44 by breaking the toggle joint at pin 67 of the latch member and permit the clamp to be raised from the car by action of lever 55. The lost motion between the link 65 and lever 65 permits relative movement between the lever and link as the cradle is righted so that pressure between the pawl and rack teeth due to the resiliency of the car springs is relieved to enable the pendulums Hill, It! to break the toggle effect of the pawl and link and release the pawl from the rack.

It will be apparent from the foregoing that a new and improved, rotary car dumper has been provided wherein the car is positively held in the cradle and, at the same time, SllffiClBIlt pressure is maintained on the car body to hold the wheels against the rails and prevent the car from becoming derailed and the springs of the car from dropping from the trucks.

While the preferred form of the invention has been described in considerable detail, it will be apparent that the invention is not limited to the constructions shown; for example, it can be readily embodied in a dumper provided with clamp holddown mechanism similar to that shown in Figs. 1 to 11 of United States Patent No. 2,381,723 and it is my intention to cover hereby all adaptations, modifications and changes therein which come within the practice of those skilled in the art to which the invention relates and the scope of. the appended claims.

Having thus described my invention, I claim:

1. In a rotary car dumper comprising a cradle having a platen for receiving a railway car and a clamp movable to engage the car and hold the same in the cradle when the latter is rotated, said clamp having a toothed rack, the combination of a lever pivoted on said cradle, a link pivotally connected to said lever, a pawl pivotally connected to said link and engageable with the teeth of said rack, said pawl having limited pivotal movement relative to said link, a pendulum adapted to swing said link for engaging and disengaging said pawl from the teeth of said rack,

aesasoo a counterweight attached to said lever and operative in response to rotation of the cradle toward its inverted position to urge said lever to press said clamp to the car in the cradle through said pawl and rack, and means for limiting rotation of said lever in the opposite direction.

2. In a rotary car dumper comprising a cradle having a platen for receiving a railway car and a clamp movable to engage the car and hold the same in the cradle when the latter is rotated, said clamp having a toothed rack, the combination of a lever pivoted on said cradle, a link pivotally connected to said lever by a lost motion connection, a pawl pivotally connected to said link and engageable with the teeth of said rack, said pawl having limited pivotal movement relative to said link, a pendulum adapted to swing said link for engaging and disengaging said pawl from the teeth of said rack as the cradle is rotated to invert the car therein and to right the N car respectively, a counterweight attached to said lever and operative in response to rotation of the cradle toward its inverted position to urge said lever to press said clamp to the car in the cradle through said pawl and rack, and means for limiting rotation of said lever in the opposite direction.

3. In a rotary car dumper comprising a cradle having a platen for receiving a railway car, a

clamp movable to engage the car and hold the 19 same in the cradle when the latter is rotated, the combination of clamp hold-down mechanism for applying a yielding pressure to said clamp upon rotation of said cradle to hold the car in the cradle, said hold-down mechanism including a pivoted pawl, a toothed element movable with said clamp, said pawl being engageable with teeth of said element, means operative to latchingly engage said pawl with a tooth of said element, a pivoted lever, means including a lost motion connection for pivotally connecting said pawl to said lever and supporting the pawl pivot for limited translational movement in opposite directions to yieldingly urge said clamp against the car in the cradle when said pawl is engaged with said element, said means being pivoted to said lever at a point spaced from its fulcrum, a counterweight connected to said lever and operative to urge said lever in a direction to cause said pawl to yieldingly urge said clamp against the car, and means for limiting movement of said lever in a direction to release said clamp from the car.

JOHN H. KINCAID.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,787,812 Brown Jan. 6, 1931 2,479,816 Grist Aug. 23, 1949 2,542,660 Glover Feb. 20, 1951