US3028819A - Railway car repair system and apparatus - Google Patents

Description

April 10, 1962 D. w. BROSNAN RAILWAY CAR REPAIR SYSTEM AND AFFU-XRATUSv 6 Sheets-Sheet 1 Filed Jan. 29. 1958 m n m m M e WWI M 5 W m M m V mm R \Q 7 M j 3 j a r p e k L? J U \R R All w nm 6N &\ m N W L N.

April 10, 1962 D. w. BROSNAN RAILWAY CAR REPAIR SYSTEM AND APPARATUS 6 Sheets-Sheet 2 INVENTOR Jenna's ZZZ/0.5mm,

Filed Jan. 29, 1958 April 10, 1962 D. w. BROSNAN 3,028,819

RAILWAY CAR REPAIR SYSTEM AND APPARATUS 6 Sheets-Sheet 3 Filed Jan. 29, 1958 April 10, 1962 Filed Jan. 29, 1958 D. w. BROSNAN 3,028,819

RAILWAY CAR REPAIR SYSTEM AND APPARATUS 6 Sheets-Sheet 4 INVENTOR Je/zrazls Mirna/7 1g ATTORNEYS April 10, 1962 D. w. BROSNAN RAILWAY CAR REPAIR SYSTEM AND APPARATUS 6 Sheets-Sheet 5 Filed Jan. 29, 1958 m 5 m W M n m I m c &\\ Q W HQ MNNH mhm w ATTORNEY? April 10, 1962 D. w. BROSNAN 3,028,819

RAILWAY CAR REPAIR SYSTEM AND APPARATUS Filed Jan. 29, 1958 6 Sheets-Sheet 6 INVENTOR Z 622 rzz's hffirajm n,

iz/m M, AM m.

ATTORNEYS hit This invention relates to improved apparatus for safely and economically effecting the repair of railway cars.

Heretofore, it has been general practice in repairing railway cars to move the cars onto a designated track, which in some instances would be several hundred feet in length, and effect the repairs by crews of workmen who moved from one car to another. The required tools and repair material were either carried from car to car by the crew of workmen, or in some instances the workmen would return to the tool storages for the needed equipment. The crews worked in the open, so that inclement weather frequently made working conditions unsatisfactory and slowed or interrupted the work. The past practices also entailed time-consuming safety precautions, which were occasionally ineffective to safeguard the crews working at intervals along the repair track against movement of cars into or out of the area in which they were working. A purpose of the present invention is to pro- .vide a safe, economical system and apparatus for repairing railway cars which improves the working conditions of the repairmen, increases the safeness of working conditions, and effects substantial economies in time required to make repairs.

The manner in which these objectives are accomplished will appear from the following description of the invention which will refer to the embodirnent of the invention which is illustrated in the drawings. It will be understood, however, that the specific description and drawings merely illustrate what the inventor presently contemplates as the best mode for carrying out the invention, and that it may be modified in the various ways which are apparent to those skilled in the art without departing from the spirit of the invention.

In the drawings:

FIGURE 1 is a schematic diagram of a railroad car repair system according to the invention showing the relationship of the different elements employed in making up the system;

FIGURE 2 is a schematic diagram of the repair station of the illustrated system, which is shown centrally located in FIGURE 1;

FIGURE 3 is a top plan view of an improved car-puller provided by the invention;

FIGURE 4 is a side elevational view of the same carpuller showing the pulling arm in raised position;

FIGURE 5 is a similar View of the same car-puller showing the pulling arm in lowered position;

FIGURE 6 is a detailed longitudinal sectional view of a portion of the same car-puller taken on line 66 of FIGURE 3;

FIGURE 7 is another detailed longitudinal sectional view of another portion of the same car-puller on the line '77 of FIGURE 3;

FIGURE 8 is a vertical cross-sectional view of the same car-puller on the line S--8 of FIGURE 4;

FIGURE 9 is a schematic diagram of a car-puller driving means;

FIGURE 10 is a top plan view of another car-puller employed in the illustrated system;

FIGURE 11 is a side elevational view of the car-puller shown in FIGURE 10;

FIGURE 12 is a detailed view taken on the line 12-12 of FIGURE 11;

3,028,819 Patented Apr. 10, 1962 FIGURE 13 is a front elevational view of the top portion of the pulling arm of the car-puller as seen from the line 13-13 of FIGURE 11; and

FIGURE 14 is a schematic illustration of certain of the electrical connections between elements of the system.

The general arrangement of one railway car repair system according to this invention is illustrated in FIG- URES l and 2. The repair system is preferably located adjacent or near the classification yard, and access to the repair system may be had, for example, from a track such as 10 shown at the left side of FIGURE 1.

As in prior practices, cars requiring repairs are accumulated on a shop track in the classification yard, and at various intervals, generally once during each work shift, the cars are shifted from the shop track on to the repair track, in this case, into the repair system by way of the track It). An access switch 16 controls the entrance into the repair system from the track 10, and this switch is normally closed in line with the track It). The illustrated repair system comprises three repair tracks identified in FIGURE 1 as T1, T2 and T3. Access to these three tracks is governed by the switches 15, Iii and 19. These switches are remotely controlled and interlocked, as will be described in more detail hereinafter. Each of the repair tracks consists essentially of four sections which are indicated as A, B, C and D with respect to track T1 on FIGURE 1 of the drawings. The first section A is that into which the cars are moved by the switch engine and, as described above, the entrance to this section is monitored by the switch 16 and its associated blue flag 17. This section A extends to the derail or turn-out switch Ztl and its associated blue flag 21. The switch 16 which controls access to track T1 is manually operated but electrically locked, and the lock is remotely controlled from the repair station. The exit switch 2% is similar, and the blue flags associated with each of these switches operates in coordination with the respective switch, the blue flag being swung across the track (raised) when the switch is locked, and clear of the track (lowered) when the switch is unlocked. The switches 16 and 20 are electrically interconnected so that when switch I6 is unlocked the switch 2%} is automatically opened with respect to the track TI, and its blue flag 21 is raised. The section A,

at a point a short distance forward of the switch 20 is the circuit of the power supply to an indicator light 24.

This light is normally on, and the power supply to it is shorted out when a car spans the rails of the isolated section. Section A is also provided with a car puller P which travels longitudinally between the rails of the trackTl and can be remotely operated to move a cut of cars from the section A into the foliowing section. B. As indicated in FIGURE 1, section B extends from the derail switch 29 to the covered repair station indicated generally by the numeral 24. The section B is provided with a car puller P1, which is similar in design and function to the carpuller P associated with section A.

Section C of the track T1 comprises the track lying in the repair station 24 and also that extending to the derail switch 26 and its associated blue fiag 27. The section C is also provided with a car-puller P2 which serves to re-' The construction and arrangement of the tracks T2 and T3 are similar to T1 as described above, and to fa-- cilitate description of the invention reference will be made only to track Tl, it being understood that the description applies equally to tracks T2 and T3. It should also be understood that a repair system according to this invention may comprise more or less than the three tracks of the exemplary system shown and described herein.

For purposes of illustration, it may be assumed that it is desired to move a number of cars onto the repair track T1. In this event, the switch 16 would be closed with respect to the track T1 by the switch engine crew. Before this was done, however, it would have been determined that the switch 26 was opened to derail with respect to the track T1, and its associated blue flag raised, thus indicating that the track T1 was in condition to receive cars for repair. Due to the interlock between the switches 16 and 20, the fact that the switch 16 is closed with respect to the track T 1 would require that the switch 28 be in derail position. It will be seen, therefore, that the open switch 20 safeguards against any movement of the cars in section A by the switch engine endangering a workman at the repair station. The switch 16 is interlocked with the power supply circuits to the switch 26 and also of the carpuller P, both of which are remotely controlled from the repair station, as illustrated diagrammatically in FIGURE 22. Thus, when the switch 16 is closed with respect to the track T1, as described above, the workmen at the repair station are unable to operate any of these elements until the switch engine has uncoupled the cut of cars delivered to section A, moved clear of the repair system, and again set the switch if in open position with respect to the track T1. This assures that operation of the switch 20 or car-puller P will not occur while the cars are under the control of the switch engine, which would quite possibly result in damage to the car-puller or a derailment.

Normally the switch engine moves the car to be repaired into section A until the indicator light 24, which is normally on, is extinguished, thereby indicating that the lead car of that cut has reached the insulated rail section 22, which is located just forwardly of the derail switch 2%. The switch engine crew will then pull the cars back until the light again lights, uncouple the desired number of cars, withdraw from the repair system, and return the switch 16 to its normal position as described above. This will restore control of the switch 20, and the carpuller P to the repair station.

When the operator at the repair station desires to move the cut of cars from section A into section B, preliminary to positioning the cars for repair in section C, the switch 29 is closed, thus locking the switch 16 and swinging its blue flag across the track. The car-puller P is then caused to move beneath the cut of cars to the rear of the last car.

This rearward movement of the car-puller is stopped by a limit switch, as explained in more detail hereafter with reference to FIGURE 9. The car-puller comprises a retractable pulling arm which is automatically lowered to pass clear beneath the cars during its rearward movement and which is automatically raised to pulling position when the car-puller is moved forwardly. This and other details of construction of the car-puller P are explained hereinafter with reference to FIGURES 3-8. When the operator causes the car-puller P to move forwardly it engages the axle of the last car of the cut and moves them almost entirely into section B, whereupon its forward movement is stopped by a limit switch. The cars towards the front of the out are then in position to be moved by the car-pulled P1, which is similar in construction and operation to P, except that P is operated at a higher speed. Pl is used frequently to at least aid in spotting the cars relative to apparatus employed in the repair station and a slower speed is desirable for this purpose. It has been found that a speed of about 60 feet per minute is suitable for P and about 40 feet per minute for Pl, although it will be apparent'that any other speeds may be employed and that P and P1 may be operated at the same speed if desired.

When one of the front cars of the cut is engaged by P1 the cut is moved entirely onto section B. The switch 2t) is then opened to derail with respect to track T1, its blue flag 21 being raised, and thus unlocking switch 16 and lowering its blue flag. The car-puller P1 may then be run to its rearward position, and upon being moved forwardly thereafter will engage the back axle of the last car of the cut. The forward movement is continued until the first car of the cut is properly positioned in the repair station of section C. In some instances is may be desirable to move the cut of cars to the point where the first car can be decoupled and picked up by the car-puller P2, and the positioning accomplished with P2. P2 is operated at about feet per minute, a high enough speed to discharge cars from the repair station with enough momentum to carry them well into section D, the release track.

The arrangement of the repair station in section C is diagrammatically illustrated in FIGURE 2. All the repair work is performed in this repair station which is under cover. Since all the work is done in this centralized, sheltered area, which is well illuminated, the car repairs may be carried on efiiciently on a 24-hour-a-day basis. The repair station includes a pair of hydraulic jacks 56, which are located on either side of the track Ti, and are adapted to engage the lateral edges of a car frame and raise it. This is done when it is desired to remove one of the car trucks or to make under-frame repairs. Preferably, these jacks are retractable to where the upper surfaces of the pistons are flush with the working platform. A jack 6! is located midway between the rails of the track, to lift cars, such as tank cars, which are not susceptible to being raised at their lateral edges. The repair station also comprises a storage 61 for materials and parts required in making repairs. In this area, there are also located impact wrenches, welding and cutting torches, oil, grease, and air brake test devices, all of which are suspended from posts at the car locations. Preferably these tools are mounted on take-up reels so they may be readily reached when needed and automatically re-stored.

To aid in spotting a car in position to be lifted by the jacks 56, 58 or 66, there is provided any conventional car-retarder 62 which is operated to grip the wheels of the car being positioned. The repair station also comprises swinging boom cranes 64, 66 adapted to support electric hoists above the track. These cranes are utilized where a car truck requires dismantling or assembly. In such instances, one end of the car is jacked up, the truck removed and rolled to a position beneath the boom of the crane.

When the repairs on a car have been completed, it is removed from the repair station by means of the carpuller P2. The driving means for this car-puller are the same as that used for car-pullers P and P1, illustrated in FIGURE 9. The car-puller itself is of lighter construction, and this is later described with reference to FIG- URES 10-13. This car-puller delivers the car to a slight downgrade at the derail switch 26 which marks the forward end of the release section D. The car then continues to roll toward the end of the release section where it is stopped by a slight elevation of the track.

The repaired cars are periodically removed from the release section and returned to the classification yard. When notified that repaired cars are to be removed, the operator at the repair station locks the derail 26 with respect to the track T1, causing its blue flag to raise and simultaneously unlocks the switch 28 and lowers its blue flag, so that the switch engine crew may open the switch 28 for access to track T1. Here again, the workmen in the repair station. are automatically safeguarded against the movement of cars in the release section by the open switch 26 and its associated blue flag.

The manner in which the car-puller P is actuated is illustrated schematically in FIGURE 9.

The operation of the car puller is controlled from a control panel 30 which is located in the repair station.

The car-puller P is mounted to run between the rails of the track T1. A motor 32 drives a double-wound drum 34. A main pulling cable 36 extends from the drum around the sheaves 38, 40, and is attached to the front end of the car-puller P. A lighter retracting cable 42 extends from the drum to a counterweight tower, indicated generally by the numeral 44, around the sheaves 46, 48 and is attached to the back end of the car-puller P. It will be understood that the function of the counter weight tower 44 is to prevent slack in the cables 36, 42, irrespective of stretch or expansion of the cable which may occur. Inasmuch as the car-puller P is under load only when being pulled by the cable 36 in the direction of the arrow in FIGURE 9, the weight in the counterweight tower only needs to be sufiicient to overcome the force required to retract the car-puller by means of the cable 42.-

The car-puller assembly also comprises a limit switch 59 which is positioned beyond the clea ance point for the track T1, and consequently, to the rear of the last car in any out which is delivered into section A. The limit switch St) is thus operated when the car-puller is retracted. and defines its limit of travel in that direction. A similar limit switch 52 is positioned to the rear of the sheave 4i) and limits the travel of the car-puller in the forward direction. The driving and control means for the carpullers P1 and P2 are the same as that described above.

The construction of the car-pullers P and P1 are the same. This construction is illustrated in FIGURES 3-8. Referring to FIGURES 3 and 8, it may be seen that the car-puller comprises a frame having three longitudinal members 70, 72 and 74. The members '72, 74 are held spaced apart by the transverse plates 76, 7S and 81) which themselves are about an equal distance from one another along the length of the car'puller. The longitudinal frame members 74 72 are spaced apart by the plates 82, 8-4. This framework supports the retractable pulling mechanism, which can be seen best in FIGURES 4, and 6. Referring to FIGURE 4, the pulling mechanism is shown in its raised position, such as it would be in when stopped by the limit switch 52, shown in FIGURE 9. The arrow indicates the forward or pulling direction. The pulling mechanism comprises the pulling arm 86, the lower end of which carries a transversely extending pin 88 which rides in slots 90 formed in the longitudinal frame members 72, 74. The pulling arm is thus enabled to rock between the upright position shown in FIGURE 4 and the retracted position shown in FIGURE 5. The movement of the upper end of the arm 86 is guided by the arm 92 which pivots about the pin 94 which in turn is supported at either end in the frame members '72, 74. The upper end of the arm 92 is pivotally connected to the arm 86 by the transversely extending pin 96. The upper end of the arm 86 carries rollers 98, positioned to engage the axle of a car being pulled. A further axle engaging roller 1'02 is carried on the upper end of the arm 92. These rollers prevent scoring of the car axles. A retracting arm 104 is fixed to the pulling arm 86 towards its lower end. The rearward end of this arm is attached to the retracting cable 42, which has been described in connection with FIGURE 9. When a pull is exerted on the cable 42, the lower end of the arm 86 moves rearwardly, the pin 88 sliding in the slot 98, until the arm 86 assumes the position shown in FIGURE 5. The upper end of the arm 92 is also drawn downwardly, so that both arms pass clear beneath the car axles when the car-puller is thus being retracted to the position where its rearward movement is interrupted by the limit switch 50. The car-puller alsocomprises a raising arm 106 which is shown in detail in FIGURE 7. This arm is pivotally supported on the pin intermediate the frame members 70, '72. This arm is held at all times in a generally upright position by the spring 198 fixed to the arm beneath its pivot point, and by a linkage which includes the rod 110, also fixed to the arm beneath its pivot point. The arm 196, as shown in FIGURE 5, remains generally upright when the car-puller is being retracted, and the upper end of the arm contacts the axles and other parts of the car as it passes thereunder, the spring 108 yielding sufiiciently to permit the arm to pass. The arm 186 carries a cam 112, which coacts with a finger 114 mounted on the arm 92. The arm also operates a linkage, which includes the rod 110, which coacts with the lower end of the pulling arm 86. The function of the arm 1%, through the agency of this cam and linkage, is to initiate rocking the arm 86 to its pulling position when the car-puller is started forward by the pulling cable 36. Referring to FIGURE 4, it may be seen that the pulling cable 36 is attached to the arm 86 by the pin 116 which also attaches the retracting arm 1M. When the arm 86 is retracted, the pin 116 is lowered to the point where tension on the pulling cable 36 will cause the entire carpuller to move, rather than rocking the arm to its upright position. This is overcome by the operation of the raise arm 186. Referring to FIGURE 5, it may be seen that the upper end of the arm 1&6 is disposed forwardly, so that its roller 117 engages the car axle as the car-puller is moved forward. As the forward movement of the car-puller continues, the upper end of the arm is pivoted rearwardly, and the cam 112 presses the finger 114 on the arm 92, upwardly. This raises the distal end of the arm 92 which is pivoted at 96 to the pulling arm 86, thus raising the pin 116 to which the pulling cable is attached to the point where the arm 86 will be rocked to its upright position (FIGURE 4) by the pulling cable.

This initial raising action, which breaks what approaches a dead center relationship between the arms 2 and 86, may be further assisted by the linkage which includes the rod 110. The rearward end of the rod 110 p is pivoted at 126) to a cross link 122 which in turn is pivotally supported on the pin 124 mounted on the transverse plate 78. The other end of the cross link is connected to the crank arm 126 by the link 128, the crank arm being pivotally supported on the pin 130, also mounted on the plate 78. The rear'edge of one end of the cross link 122 bears against the piston of a springloaded hydraulic cylinder 132 which is mounted on the frame member 74. When the pulling arm 86 is retracted,

as described above, the lower end of the arm strikes against the distal end of they link 126 and through the linkages 128, 122, 110, causes the upper end of the raise arm 106 to move slightly forward, but not sufiiciently to avoid contacting the axles of the cars. Upon contacting the axles, the upper end of the arm 106 is caused periodically to move even further forward, but raises up when it loses contact with the car by action of the spring 108. This bobbing action is dampened by means of the springloaded hydraulic cylinder 132. When the car-puller is started forward, the arm 106 first contacts the car axle,

lighter construction than otherwise possible, and also avoids deformation of the frame as well as heavy wear and scoring of the plate on which the car-puller runs.

The car-puller is provided with a set of forward ground Wheels 13 i, 136, and a rearward set 138, 140, 142. Referring to FIGURE 8, it may be seen that these wheels run on a plate 144 which lies between one of the rails of the track T1 and an angle iron 14d mounted on the ties parallel to the rail. The frame member 70 is provided with a guide 148 which bears against the inner side of the web of the rail.

the arm 86 comprises two parallel bars, 86a and 86b,

Through the described linkages, the.

which are joined together at their bottom edges by the transverse piece 860, and it is this latter which bears against the distal end of the crank 126 when the arm 86 is retracted. It may also be seen in these figures that the arm 92 comprises two sections, 92:: and 92b, which are connected by the pin 96. Each of these sections comprises two bars which are rigidly spaced from one another, and between which the rollers 102 are supported.

The construction of the high-speed car-puller P2 is illustrated in FIGURES -12. Referring to FIGURES 10 and 11, it may be seen that the car-puller comprises two side frame members 150, 152, and that the lower end of the pulling arm 154 is pivotally supported therebetween on the pin 156. The lower end of the arm is reinforced with side plates 158, 160, as seen best in FIG- URE 12, and these plates are shaped to provide a forward extension 162 to which one end of the spring 164 is attached. The other end of this spring is affixed to the pin 166 which is supported at either end in the side frame members 150, 152. This spring acts to retain the arm 154 in an upright position. Intermediate the side frame members, at the back of the arm, is aflixed a stop 163 which prevents the arm from swinging backwardly beyond the vertical position shown in FIGURE 11. The lower portion of the arm is circular, however, so that the arm is free to swing forwardly. The arm is sufficiently long, so that it contacts the car axles, pivoting forwardly in order to pass beneath them, as the car-puller is retracted. When the car-puller is moved forward, the rollers 170, 172 on the upper end of the cam engage the car axle, as illustrated in FIGURE 11. The upper end of the arm is provided with side plates 174, 176 which are spaced apart at their upper ends. The rollers 170, 172 are mounted on pins, which are received in these plates, as shown in FIGURE 13. Referring to FIGURE 10, the car-puller is provided with a forward set of wheels 180, 182 and a rear set 184, 186. These wheels travel in the spaced apart channel bars 190, 192. At the front end of the car-puller, between the side frames, is mounted a pulley 194 to which the pulling cable is attached. A similar pulley 196 is mounted at the back end of the car-puller for attachment to the retracting cable.

Referring to FIGURE 14, the switch lock for switch 16 is shown diagrammatically in its open position wherein the associated blue flag 17 is lowered (swung clear of the track). The switch lock comprises means for interrupting the power supply to switch 20, and its blue flag, and to car-pulling means P, when it is open, as also shown diagrammatically in FIGURE 14. The locks of switch 16 and switch 20 are interconnected so that switch 20 is moved to derailing position when the locit of switch 16 is open. The blue fiag 21 is then coordinately swung across the track (raised). Similarly the locks of switches 26 and 28 are interconnected so that one is opened when the other is closed, and the blue flags are correspondingly swung across the track (raised) when respective locks are closed.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A railway car-puller comprising a frame having a slot therein, a retractable pulling arm movable between a lowered and raised position, a pin on the lower end of said arm slidable in said slot as the pulling arm is moved between its raised and lowered positions, a second arm pivoted at one end to said frame and at its other end to said pulling arm above said pin, a pulling cable attached to said pulling arm and extending in one direction therefrom, a retracting cable attached to said pulling arm and extending in the other direction.

2. A railway car-puller as described in claim 1 comprising a third arm pivotally supported on said car-puller and yieldingly maintained in a generally upright position, a cam on said third arm and a cam follower on said second arm overlying said cam.

3. A railway car-puller as described in claim 2 comprising a crank arm supported on said car-puller positioned to be engaged by the lower end of said pulling arm when said arm is retracted, a linkage between said third arm and said crank connected to urge said pulling arm forwardly towards its unretracted position when said third arm is moved rearwardly.

4. An apparatus for use in repairing railway cars comprising a repair station, a car storage station adjacent one side of the repair station and a car receiving station adjacent said storage station, means operable to permit or prevent movement of cars from said receiving to said storage station, selectively, mechanical means operable in both the receiving station and said storage station for delivering cars through said movement control means from said receiving station to the storage station, a control station, means at said control station for actuating said mechanical delivery means, and means interconnecting said movement controlling means and said actuating means to disable said delivery means operable in said receiving station when said movement controlling means is operable to prevent movement of cars to said storage station.

5. A railway car-puller comprising a frame, a retractable pulling means mounted on said frame movable to a raised position in which it is engageable with a car axle when the puller is moved forward, said pulling means having mounted thereon a set of freely revolvable rollers spaced to engage, respectively, the upper and lower portions of a car axle, whereby the axle is nested between the rollers when the said pulling means is in its raised position and in engagement with a car axle.

6. A railway car-puller comprising a frame, a retractable pulling arm mounted on said frame and movable between a lowered position and a raised position in which the distal end of the said arm is engageable with a car axle, and a pulling cable and a retracting cable attached directly to said pulling arm intermediate the distal end of the arm and the mounting of the arm on the said frame.

7. An apparatus for use in a railway car repair system comprising a first station for receiving cars to be repaired, a second station adjacent said first station, railway rails extending through each of said stations, control means selectively operable to permit or prevent movement of cars along said rails from said first station to said second station, mechanical delivery means operable in both of said stations for delivering cars on said rails through the said control means from said first station to said second station, a control station, actuating means at the control station for actuating said mechanical delivery means in either of said stations, and means interconnecting said control means and said actuating means to disable the mechanical delivery means against operation in said first station when the movement control means is operable to prevent movement of cars to said second station.

References Cited in the file of this patent UNITED STATES PATENTS 522,300 McClellan et all July 3, 1894 552,900 Fitzgerald Jan. 14, 1896 999,190 Connelly July 25, 1911 1,000,680 Kieffer Aug. 15, 1911 1,130,433 Richter Mar. 2, 1915 1,478,676 Richey Dec. 25, 1923 1,484,086 Rutherford Feb. 19, 1924 1,557,784 Sharpnack Oct. 20, 1925 1,706,211 Coffey Mar. 19, 1929 1,798,581 Bentley Mar. 31, 1931 1,927,201 Bone Sept. 19, 1933 2,040,353 Wilson May 12, 1936 2,190,073 Knudsen Feb. 13, 1940 2,767,662 Howard et a1 Oct. 27, 1956 FOREIGN PATENTS 79,779 Austria Jan. 26, 1920 287,036 Germany Sept. 10, 1915

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