US1555831A - Safety stop for traveling structures - Google Patents

Description

Oct. 6,1925. 5 7 1,555,831

A. F.- CASE SAFETY STOP FOR TRAVELING STRUCTURES Filed April 1'7 1922 3 Sheets-Sheet l A. F. CASE SAFETY STOP FOR TRAVELING smuc'sunss s sheets-sheet 2 Fild April 1'7, 1922 Oct 6, 1925.. I ggg g g A. F. CASE; Y

SAFETY STOP FOR TRAVE'LTNG STRUCTURES Filed Aprii' 1m 922 3 SheetS--Sheet s a n Ma 7% ab Patented Oct. 6, 19 5 UNITED STATES PATENT OFFICE.

ARTHUR F. CASE, OF CLEVELAND, OHIO, ASSIGNOR TO THE WELLMAN-SEAVEBJEOR; GAN COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

SAFETY STOP FO'R TRAVELING STRUCTURES.

Application filed April 17, 1922. Serial No. 554,080.

To all whom it may concern:

Be it known that I, A THUR F. CASE, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Safety Stops for Traveling Structures, of which the following is a full, clear, and exact description.

This invention relates to what may be termed a safety stop for structures adapted to travel along a trackway, and has particular reference to a safety stop for material conveying bridges, to hold the structure against movement by wind pressure on it.

Large traveling bridges have on more than one occasion been wrecked by being impelled along the trackway by wind pressure notwithstanding the application of friction brakes, and to avoid wreckage of traveling structures such as these bridges, track clamps have been provided, two or more of which have been secured to each supporting leg of the bridge, these clamps consisting of pairs of jaws which are designed to be set by counterweights to frictionally engage opposite sides of the rails, and to be released by power usually derived from one or more electric motors which lift the counterweights and thus disengage the jaws from the track rails when the structure is to be moved along the track.

The car clamps heretofore employed have not proven to be entirely satisfactory, for bridges are known to have been wrecked notwithstanding the factthat they were equipped with a series of the rail engaging clamps which though set to engage the rails as tightly as the nature of the apparatus permitted, were not effective to hold the structure against drifting along the trackway under the pressure of an unusually heavy wind. Furthermore, aside from the fact that the prior clamps do not afford absolute protection, they are as a rule very complicated by reason of the fact that they involve great deal of apparatus in the way of cables, sheaves and hoists scattered throughout the structure and extending from the lower portions of the supporting legs up to and along the bridge proper to the point where the clamps are designed to be controlled. Because of all this apparatus used in conjunction with the car clamps themselves, and required for their operation,

the clamps often get out of order and for that reason are unreliable.

The principal objects of the present inventionare to provide first an efficient stop which is not solely dependent upon the frictional gripping of clamp members to the sides 'of the rails to hold the structure against movement, but has a more reliable and a more efiicient holding device in the form of a wedge which is designed to be inserted between the wheel and the track.

Further the invention aims to provide a safety stop in the form of a self contained unit having to a marked degreethe advantage of simplicity, and which is free of all complicated operating parts so susceptible to injury and derangement, such as ropes, sheaves, winding drums and the like.

Still further the invention aims to provide a safety stop in the form of a unit located next the runway where the location is favorable for examination and where repairs can be easily made.

Finally it is the aim of the invention to provide a safety stop, a series of which can be readily applied to old as well as new traveling bridges.

The safety stop involving my invention, is as far as I am aware, new in structure and principle, particularly so far as safety stops are concerned adaptable in a commercial or practical way especially for structures of the type for which my device is designed to give protection.

This stop has a number of new features which are not necessarily combined in one structure, but are susceptible ofadvantageous conjoint use to provide maximum efficiency. Among these features is a wedge adapted to be lowered onto the track and under the wheel to positively block its movement; a device which may be in the form of a clamp for engagement with the rail to prevent the wedge being pushed along the track by the wheel of the structure; also power operated means for actuating the wedge and clamp; an arrangement wherein all these parts are in a self contained unit, preferably suspended from the leg of the bridge; also an arrangement wherein the parts are set by a counterweight and released by a motor, with the motor itself arranged to serve as a counterweight.

The above and other features constitute my invention which may be briefly summarized as consisting in certain novel details of construction, and combinations and arrangements of parts which will be de scribed in the specification and set forth in the appended claims.

In the accompanying sheets of drawings wherein I have illustrated an embodiment of the invention which operates with high efficiency, Fig. 1 shows a side elevation of a material conveying traveling bridge for which my invention is particularly utilized, it being intended that two or more of my improved safety stop devices be provided on each leg or supporting part of the bridge; Fig. 2 is an end view of the lower portion of one of the legs of the bridge showing the lower still provided at its ends with my improved safety stops, each adapted to stop the movement of the structure in one direction along the trackway; Fig. 3 is an enlarg;d side elevation of the safety stop showing the same attached to the sill, a portion of the latter and a portion of the track wheel with which the wedge co-operates being shown; Fig. 4 is an end view of the same, with the rail in section; Fig. 5 is a view similar to Fig. 3, showing the safety stop applied or set so as to hold the structure against movement, whereas in Fig. 3 it is shown released.

Referring now to the drawings, in Figs. 1 and 2 I have shown conventionally a material conveying traveling bridge in connection with which my invention has particular utility. The bridge comprises an upper horizontal portion or bridge proper 10, supported on legs 11 provided with trucks having wheels 12 adapted to travel along the bridge trackway. In some instances the truck wheels on each side travel over a single rail as herein illustrated and in other instances along doubl rails, but whether there are two rails or a single rail on each side of the trackway is immaterial to the present invention.

In accordance with the present invention as herein illustrated, I attach to the lower sill 18 of each leg 11 a pair of my safety stop devices, preferably provided forward of the front wheel of the forward truck and behind the rear whtel of the reartruck so that movement of the bridge in either direction may be prevented.

By reference to Figs. 3, I and 5 it will be seen that each safety stop is in the form of a self contained unit which is suspended from the sill, it being a feature of the present invention that a rigid connection between the stop and sill of the bridge leg is unnecessary.

The stop comprises a casting or body member 14;, adapted to be swung to and from engagement with the rail as shown. The lower part of the casting is provided with feet or flange-like members 15 which at all times extend down freely along opposite sides of the rail to keep the casting central over the rail, and the casting is pro vided also with a wedge or nose 16 having a part curved in conformity with the curvature of the truck wheel 12 so that it can be insert id between thewheel and rail to produce the effect of a blocking wedge when the casting is lowered onto the rail.

It is desirable that means be provided to keep the wedge from sliding along the rail, and while this may assume different forms, it consists preferably of a pair of clamp levers 17 pivotally supported at 18 on opposite sides of the casting 1d so as to be capable of swinging in a plane transverse to the casting and to the rail. These clamp levers which are pivoted between their ends, are provided at their lower ends with rail engaging jaws 18*, and at their upper ends they are connected in this instance by links 19 to crank arms 20 pivotally or rotatably supported by means of pins or short shafts 21 journaled in bosses 22 on opposite sides of and at the upper front part of the casting 14. These pins carry bevel gears segments 23 which mesh with a double bevel gear segment 24 which moves up and down between the bevel gear segments 23, and this double bevel gear segment is carried by an operating arm 25 pivotally supported by means of a pin or stud 26 mounted in bosses 27 at the top central portion of the casting 14:. The opposite end of this arm 25 is extended to form a support 28 for a motor 29 forming a part of th self contained unit referred to, and serving both as a counterweight to set the stop in operative position, and also as a power means by which the stop is operated.

In this instance the motor drives a worm 30, indicated by dotted lines in Figs. 3 and 5, and this worm engages a worm wheel 31, both the worm and the worm wheel being carried by the arm and enclosed in a portion thereof forming a gear case 32*. The worm wheel 81 is on a shaft 82 extended to each side of the arm 25 to form a support for two lifting levers 33 provided at their free ends with rollers 34 adapted to roll on the inclined top surface of the rear portion 35 of the casting 14;.

The parts are so arranged that the rotation of the motor in one direction causes the lifting levers to exert a pressure on the main casting and lift the motor end of the pivoted arm 25. This causes the bevel pinions 23 to revolve in the proper direction to release the grip of the clamps on the rail, and also has the additional effect of lifting the unit away from the wheel and rail to inoperative position, as will be explained, the parts then being in the position shown in Fig. 3. It might be stated that when the parts reach the position shown in this figure, the rollers the motor is stopped, preferably automatias already stated.

cally, but the motor. controlling switch may be in the form of a limit switch onthe arm 25. Such a device being common in the art forms no part ofthe present in vention and is not illustrated herein.

hen the'motor'revolves in the opposite direction'the lifting levers 33 are reversed and the motor end of the pivot-ed arm descends by gravity, this motion causing the clamps to grip the rail. As soon as this grip is effected, the pivoted arm 25 with the motor 29 serving as a counterweight ceases to rotate onits axis 26, and continued rotation of the'lifting arms causes the rollers to leave their path on the main casting 14, thus allowing the full weight of the motor and its associated parts to act as a counter- Wveight to maintain the grip of the clamps 17 on the rail. However, prior to the time that the clamps engage the rail the unitswings down onto the rail or to the position shown inFig. 5, so that the wedge16 is inserted between the wheel '12 and rail. When the levers 33 reach substantially the position shown inFig. 5,"the motor is stopped preferably automatically by a limit switch not shown.

The safety stop when in operatingpo'sition rests on the runway rail and has no rigid connection whatever with the bridge For the purpose of suspending the stop when in inoperative position, or while the bridge is'in'motion, forward and rear suspending links 37 and 38 are provided; In this instance there is a single forward link '37, and preferably there are a pair of the rear links 38 extending entirely upwardly toward the sill on 0pposite sides of the casting and pivoted arm 25. The forward link is pin connected at 39 to the upper front part of the casting 14,

and the rear links arepin connected at 40 to the rear part of the casting 14. The upper ends of the links have slotted holes for pins 41 by which the links are connected to brackets 42 on the under side of the sill 13 of the bridge leg. The upper pins 41 are forward or toward the wheel from the pins 39 and 40 by which the lower ends of the links are connected to the casting, so that the effect of gravity will be to swing the casting downward and inward onto-the rail and between the wheel and rail.

It is apparent from this arrangement that if a force is applied to causethe casting to move in a direction away from the wheel,

the links will cause it to move forwardly as well as outwardly, with the result that the wedge end 16 of the casting is withdrawn from contact with the wheel, and at the same time thecasting 14 is lifted oif-therail. In'this position thestop is out of ser vice, and is supported from the sill by the suspending links; For the purpose of'exerting the necessary force to cause this move ment of the stop, a lifting link 43 is provided. This link is in this instance connected tothe pin 41 by which the rear links 38 are connected to the sill, and the lower end of this link is provided with a slotted hole 44, receiving a pin 45 carried by the upper inner end of the pivoted arm 25, the location of these pins being such that the top pin of the lifting link is back of, and above or further away from the wheel thanthe pin 45 on the pivoted arm.

Due to the position of thislifting link 43, it forms an approximate diagonal of the equilateral connecting the four pins of the supporting links 37 and 38. Itis evident that a force which causes this diagonal to shorten will cause the other diagonal to lengthen, and inasmuch as any change in this length must-necessarily change'th'e position of the link pins 39'and 40', relative to the corresponding pins-on the-bridgesil-l 13,

the lengthening of'this. diagonal distance,

i. e. the long diagonal, will cause the-entire stop unit to swing away from the wheel and rai The lifting link 43 is of such lengththatwhen the pivoted arm is being swung upward and has released the clamps, the pin 45 of the arm engages the end of the slotted l1o'le'44 of the lifting link 43, and a further rotation of the arm exerts a pull on this linkwhi'ch produces the effect of shortening the diagonal which this link approximates as above stated, and the stop is thereby lifted to the out of service position shown in Fig. 3.

On the other hand, when the motor 29 is operated to lower the motor end of the pivoted ar1n25, the initial rotation or downward swinging movement of the arm relieves the lifting force and the unit gradually swings by gravity to operative position onto the rail with the wedge under the wheel as shown in Fig. 5, and further downward swinging movement of the arm 25 applies theclamp arms 17 as already explained.

As previously stated, the upper ends of the suspending links are provided with slotted holes, the purpose being to allow for slight movement of the bridge toward the safety stop after the clamps have beenset without producing compressive stresses in the links.

As before stated, each traveling bridge has a series of the safety stops above described; that is to say, two or more on each leg of the bridge. The several motors of the stop devices are preferably controlled simultaneously through i3l16"1116ll11111 0f a single controller or from a single controlling pointpreferably located at the operators station on the bridge proper, and the controlling wires will be extended along the bridge and down the legs and will be connected to the motors in any suitable manner, such control devices being common in the art they are not herein illustrated.

When the bridge is stationary all the safety stop devices will be set as shown in Fig. 5, the motors 29 then being de-energized, and when the stop devices are in the position shown in Fig. 5 the wedges are set between the track rails and the truck wheels and the clamps are held by the counter weighted levers in clamping engagementwith the sides of the rails so as to prevent the wedges moving along the rails.

When it is desired to move the bridge along the trackway, the motors 29 of the several stop devices are energized and operated in a direction such that the lifting levers 38 are rotated so as to cause the rollers 54k to be lowered onto the rear inclined surfaces of the castings 1i, and then to travel in" wardly along the same so as to lift the pivoted levers 25 from the position shown in Fig. 5 to the position shown in Fig. 3. This movement of the pivoted arms 25 first causes the clamps to be released from the rails and then causes the units to be bodily swung to the inoperative position shown in Fig. 3, and when the lifting levers reach the depressions in the castings, the motors are automatically stopped and the pivoted levers 25 with their motors are retained in lifted position with the clamps released and the wedges withdrawn from the rails and wheels.

lVhen the bridge has been moved to the point desired, the safety stops are again set, this being done by simultaneously operating the motors in the-opposite direction so as to rotate the lifting arms 33 in the reverse direction and lower the pivoted arms 25. As the arms 25 swing downward the body members or castings 14 of the several stop de vices swing down onto the rails with the wedges between the rails and the truck wheels and then set the clamp, and after the lifting arms or levers 33 and their rollers 34 move clear of the castings so that the whole weight of the arms 25 with their motors act to hold the clamp jaws in engagement with the rails the motors will. automatically stop.

Thus it will be seen that I provide safety stops which embody many new features, and that the objects stated at the beginning of the specification are attained to a very high degree. Though I have shown only the preferred construction, various changes may be made, and I do not desire to be confined to the exact details shown, but aim in my claims to cover all modifications which do not involve a departure from the spirit and scope of my invention.

Having described my invention, I claim:

1. A safety stop for traveling structures movable along a trackway comprising a wedge adapted to be inserted between a wheel of the structure and a rail, movable means associated with the wedge and engageable with a portion of the trackway for preventing the wedge sliding along the rail, and means for actuating the first mentioned means and for shifting the wedge.

2. A safety stop for traveling structures movable along a trackway, comprising a wheel blocking wedge engageable between the rail and wheel and a rail engaging clamp.

3. A safety stop for traveling structures comprising a wheel blocking wedge engageable between the rail and wheel a rail e11- gaging clamp, and means for withdrawing the wedge and releasing the clamp.

l. A safety stop for traveling structures movable along a trackway, comprising a eounterweighted clamp and a wheel blocking wedge engageabl between the rail and wheel.

5. A safety stop for traveling structures movable along a trackway, comprising a rail clamp and a gravity actuated wheel blocking wedge engageable between the rail and I wheel.

6. A safety stop for traveling structures movable along a trackway, comprising a wheel blocking wedge adapted to be inserted between a wheel and a rail and a rail clamp for preventing movement of the wedge along the rail, and power means for releasing the clamp and lifting the wedge out of operative position.

7 A safety stop for traveling structures movable along a trackway, comprising a wheel blocking wedge adapted to be inserted between a wheel and rail, a rail engaging clamp for preventing movement of the wedge, a counterweight for setting the clamp, and power means for swinging the wedge from operative position and for releasing the clamp.

8. A safety stop for traveling structures movable along a trackway, comprising a movable member adapted to be lowered onto a rail of the trackway, and provided with a wheel blocking wedge adapted to be inserted between a wheel and a rail, rail gripping means carried by the wedge and engageable with a portion of the trackway to prevent movement of the wedge along the rail, and means operable to move said first mentioned means out of engaging position and to shift said member away from the wheel.

9. A safety stop for traveling structures movable along a trackway, comprising a member supported from the structure and having a wedge for insertion between a wheel of the structure and the rail and having also a rail engaging clamp.

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10. A safety stop for traveling structures comprising a unit including a wedge movable into and out of a position between a wheel of a structure and the rail,-a rail engaging clamp, and an operating motor for actuating the wedge.

11. A safety stop for traveling structures movable along a trackway comprising a movable member having a wheelblocking Wedge, and a motor mounted on said movable member for actuating said-member.

12. A safety stop for traveling bridges comprising a bridge proper with a supporting leg, and a safety stop device in the form of a unit movably suspended from the leg and including a wheel blocking wedge and a rail clamp.

13. A safety stop for traveling bridges, comprising a bridge proper with'a supporting leg, and a safety stop in the form of a unit movably suspended from the leg and including a wheel blocking wedge,- a rail clamp, and an operating motor for actuating the Wedge and clamp.

14. A safety stop for traveling structures movable along a rail, comprising a member having a rail blocking Wedge, andamotormounted on said member and serving to shift said member. I

15. A safety stop for traveling structures movable along a trackway, a track engaging member mounted for movement by gravity into track engaging position, releasable means for holding said member in raised position, a rail engaging clamp carried by said member, and means for releasing said member and operating said clamp.

1-6. A safety stop for traveling structures movable along a trackway, a track engaging member mounted for movement by gravity to track engaging position, a rail clamp carried by said member, means for actuating said clamp, and releasable means for holding said member in raised position and said clamp in open position.

17. A safety stop for traveling structures movable along a trackway, a wheel blocking wedge mounted for movement by gravity into operative position between the wheel and rail, a rail engaging clamp carried by said wedge, a counterweight for operating said-clamp, and releasable means for holdingsaid wedge and said clamp counterweight inraised position.

18. A safety stop for traveling structures movable along a trackway, a track en ag ing member mounted for movement by gravity into track engaging position,-a rail clamp carried by said member, a lever for actuating said. clamp, means for holding said member in raised position and said clamp in openposition, and means for releasing said member and operating said lever to set said clamp'.

19; A safety stop for traveling structures movable along a tracldway, a movably' mounted wheelblocking wedge, and means for successively moving said wedge into engagement between the wheel and rail, and

clamping said wedge to the rail. v

20. A. safety stop comprising a member inounted to move by gravity into rail engaging as a counterweight to move said memher in one direction and operable to move said member in the opposite direction.

22. A safety stop for traveling structures, comprising'a trackengaging stop member, a combined motor and counterweight movably mounted on. said stop member, and means actuated by said motor operable. on move-' ment of the motor in one direction to move said stop member in one direction and on movement of the motor in the opposite directio'nto release said motor and permit it to act asacounterweight tomove said stop member in the opposite direction.

'23. A safety stop fortraveling structures, comprising a unit including atrack engagingstop member, suspension members connected thereto and adapted to be secured to said traveling structure, and a lever pivoted on said stop member andadapted to coact with said suspension members to raise or lower said stop member.

24. A safety stop for traveling structures comprising a unit including a track engaging stop member, suspension members connected thereto and adapted to be secured to said traveling structure, a lever pivoted on said stop member and, adapted to 'coact with said suspension members to raise or lower saidistop member, and a motor mounted on said unit and adapted to actuate sai'd 'lever to raise or lower said stop member.

25. A safety stop'for traveling structures movable along a trackway, comprising a track engaging member adapted to be movably suspended from said structure, and means carried by said movable member adapted to actuate the same to movesaid member into and out of engagement with a part" of said trackway. g

26; A safety stop for traveling structure's movable along a t'mckway comprising a track engaging member adapted to be movably suspended from said structure, and a motor carried said movable member, adapted to actuate thesame to move' said member into and out ofengagement with a part orysaidaackway. g H

27. A safety stop: for traveling structures movable along a trackway, comprising a wedge member adapted to be suspended from said structure for movement into engaging position between a wheel of said structure and the rail and to a position out of engagement with said wheel and rail, and actuating means carried by said wedge member adapted to move the same into or out of position between a wheel of said structure and the ra1l and to a position out of engagement wlth said wheel and rall, a clamp carried by said wedge member and engageable with the rail, and means carried by said wedge member adapted to move the same into or out of engaging position and to move said clamp into or out of engagement with the rail.

29. A safety stop for traveling structures movable along a trackway, comprising a track engaging. member, a pair of links pivoted to said member and adapted to be suspendedfrom spaced pivots on said structure whereby said member maybe raised or lowered by swinging movements of said links, and means carried by said track engaging member whereby said member may be moved into or out of engagement with a part of said trackway.

30. A safety stop for travelingstructures movable along a trackway, comprising a body member, a rail clamp carried by said body member, an actuating lever for said clamp carried by said body member, said lever on movement in one direction being adapted to actuate said clamp to grip the rail and on movement in the opposite direction to release said clamp, and actuating means mounted on said lever for swinging it in either direction.

31. A safety stop for traveling structures movable along a trackway, comprising a body member, a rail clamp carried .by said body member, an actuating member for said clamp carried by said body member, said member on movement in one direction being adapted to actuate saidclamp to grip the rail and on movement in the opposite direction to release said clamp, a motor mounted upon said member and forming a counterweight to move said member in one direction, and means actuated by said motor to move the member in the opposite direction.

32. A safety stopfor traveling structures movable along a trackway, comprising a body member adapted to be supported from said structure and having a rail engaging part and an actuating lever mounted on said body member, said lever having a counterweight thereon adapted to shift the same in one direction and said lever having means thereon engageable with said body member to shift said lever in opposition to said counterweight.

33. A safety stop for traveling structures to actuate said lever in one direction, and a crank arm on the motor shaft engageable with said body member for shifting said lever in opposition to said counterweight.

34. The combination with a traveling structure adapted to be moved along atrackway, of a track engaging unit comprising a body member, links for movably suspending said member from said structure, a counterweighted lever carried by said body member, said lever being connected with one of said links whereby on movement thereof in one direction said unit is raised and on movement in the opposite direction said unit is lowered into track engaging position.

35. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links for movably suspending said member from said structure, a lever carried by said body member, said lever being connected to one of said links whereby on movement thereof in one direction said body member is lowered into track engaging position and on movement thereof in the op posite direction said body member is raised to inoperative position, and actuating means for said lever carried by said unit.

36. The combination with a traveling structure adapted to be moved along a track Way, of a self contained unit comprising a track engaging body member, suspension members for movably connecting said body member to said structure, and means carried by said body member and co-operating with said suspension members to raise and lower said body member into and out of track engaging position.

37. The combination with a traveling structure adapted to be moved along a trackway, of a self contained unit comprising a track engaging body member, spaced suspension links connecting said'structure and body member, whereby said body member is raised and lowered upon swinging movement of said links, a motor carried by said unit, and means also carried by said unit and actuated by said motor to move said links angularly with respect to said body member so as to move the latter.

38. The combination with a traveling structure adapted to be moved along a trackway, of a self contained unit comprising a track engaging body 1nember,front and rear links connecting said body member to said structure, a diagonally disposed device for moving said links angularly' with'respect to said body member to shift the same, and means carried by said unit for actuating said device.

39. The combination with a traveling structure adapted to be moved along a trackway, of a self contained unit comprising a track engaging'body' member having a wedge portion engageable between a wheel of said structure and the rail upon which it runs, links connected at one end to the body member and at the other end to the structure for suspending said body member from said structure, said links being disposed at an angle to the vertical whereby said body member tends to move by gravity downwardly and longitudinally with respect to the rail to bring said wedge portion thereof into engagement between the wheel and rail, a rail clamp carried by said unit, and a single actuating means for swinging said links to shift the body member and for operating said clamp.

40. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links connecting said member with said structure, said links being pivoted at one end to the body member and at the other end to the structure, and means carried by said body member and connected with one of said links whereby on movement thereof in one direction said body member is raised,

and on movement thereof in the opposite direct-ion said body member is lowered.

41. The combination with a traveling structure adapted to be moved along a trackway, a track engaging unit comprising a body member, links connecting said member with said structure means carried by said body member and connected with one of said links whereby on movement thereof in one direction said body member is raised, and on movement thereof in the opposite direction said body member is lowered, and a rail engaging clamp carried by said body member, said clamp being adapted to be operated by said means whereby when said body member is lowered said clamp is actu- ,ited to grip the rail.

4-2. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links connecting said member with said structure, and a counterweighted lever carried by said body member, said lever being connected with one of said links whereby on movement thereof in one direction said body member is raised, and on movement thereof in the opposite direction said body member is lowered.

43. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links connecting said memwith said structure, a counterweighted lever carried by said body member, said lever being connected with one of said links whereby on movement thereof in one direction said body member is raised, and on movement-thereof in the opposite direction said body member is lowered, a rail engagin'g clamp carried by said body member and adapted to be operated'by said lever, and means carried by said unit for actuating said lever in opposition to said counterweight.

44. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links connecting said member with said structure, a lever carried by said body member, a motor mounted on said lever and forming a counterweight therefor adapted to shift said lever in one direction by gravity, said lever being connected with one of said links whereby on movement thereof in one direction said body member is raised and on movement thereof in the opposite direction said body member is lowered.

45. The combination with a traveling structure adapted to be moved along a trackway, of a track engaging unit comprising a body member, links connecting said mem ber with said structure, a lever carried by said body member, a motormounted on said lever-and forming a counterweight therefor adapted to shift said lever in one direction by gravity, said lever being connected with one of said links whereby on movement thereof in one direction said body member is raised, and on movement thereof in the opposite direction said body member is lowered, a rail engaging clamp carried by said body member and adapted to be operated by said lever, and means actuated by said motor for shifting said lever in the direction opposite to the gravity movement thereof.

as. The combination with a traveling bridge having supporting legs traveling along spaced rails, each of said legs having front and rear wheels, of stop devices supported by said structure in front of said front wheels, and at the rear of said rear wheels, each of said devices having a member provided with a rail clamp and a wedge portion engageable between the adjacent wheel and rail, the wedge portion of each of said devices being mounted for movement downwardly and toward the adjacent wheel into blocking position.

47. he combination with a traveling bridge having supporting legs traveling along spaced rails, each of said legs having front and rear wheels, of stop units supported from said structure in front of said front wheels and at the rear of said rear Wheels, each of said units having a body member provided with a Wedge portion engageable between the adjacent Wheel and 10 front and rear Wheels, of stop devices supported by said structure in front of said front wheels, and at the rear of said rear Wheels, each of said devices having a member provided with a Wedge portion engageabie between the adjacent Wheel and rail, and a rail engaging clamp.

In testimony whereof, I hereunto affiX my signature.

ARTHUR F. CASE.

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