US1813022A

US1813022A - Dump car

Info

Publication number: US1813022A
Application number: US204506A
Authority: US
Inventors: William L Burner
Original assignee: Western Wheeled Scraper Co
Current assignee: Western Wheeled Scraper Co
Priority date: 1927-07-09
Filing date: 1927-07-09
Publication date: 1931-07-07
Anticipated expiration: 1948-07-07

Description

Jufy 7.; @EL

W. L. BURNER l'l 5922 DUMP CAR Filed July 9, 1927' Juy 31931. W. L. BURNER 3983139022 DUMP CAR Filed July 9, 1927 3 Sheets-Sheet 2 M11 ,T HW M i la" l www2 Juy 7, 1931. L. BURNER DUMP CAR Filed July 9, 1927 5 Sheets-Sheet 5 Patented July 7, 1931 UNITED STATES PATENT OFFICE WILLIAM L. BURNER, OF COLUMBUS, OHIO, ASSIGNOR TO WESTERN WHEELED SCRAPER COMPANY, OF AURORA, ILLINOIS, A CORPORATION OF ILLINOIS :DUMP canl Application led July 9, 1927. Serial No. 204,506.

The present invention relates to dump cars of the type in which the body or bed of the car is tiltably mounted on the under frame for laterally dumping its load to either side of the road bed.

More specifically, the invention is concerned with an improved construction of power operated mechanism for tilting the bed to dumping position, and has for its principal objects to provide an improved construction of pneumatic power unit comprising power cylinder and p-iston element-s wherein the power cylinder has operating movement to tilt the bed to provide an improved construction of power mechanism wherein both the power cylinder and the piston have operating movement in the tilting of the bed; t-o provide power mechanism of this character in which both the cylinder and the piston have pivotal mounting on the car so that the cylinder and piston and the operating linkage will swing laterally as a unit with the angular tilting movement of the bed, whereby the tilting forces are caused to act in a straight line through the entire dump-ing movement; to provide an improved power unit comprising as an element thereof a movable air storage reservoir; to provide an improved arrangement of valve mechanism for controlling the admission and exhaust of the compressed air to and from the power operated cylinders; and to provide an improved arrangement of locking mechanism which normally locks the bed in a horizontal position, but which is adapted to be released concurrently with the opening of said valve means in the act of admitting air to either of the power cylinders.

The advantages obtained by these features of construction will be described more fully in the following description of a preferred embodiment of my invention. In the drawings illustrating this embodiment:

y Figure 1 is a transverse sectional view through a dump car embodying the invention, the left hand side of the figure being taken on one transverse plane, and the right hand side being taken on another transverse plane, this figure also illustrating the tilted position of the bed in dotted linesv Figure 2 is a fragmentary side view of the car partly in longitudinal section.

Figure 3 is a longitudinal sectional view through one of the power units and its operating linkage.

Figure 4 is a similar sectional view through a modified construction of power unit.

Figure 5 is a side elevational view of the power unit, illustrating motion equalizing devices which may be employed in conjunction with the operating linkage.

Figure 6 is a diagrammatic view illustrating the piping system for the power units.

Figure 7 is a similar fragmentary view illustrating the pipe connections employed when using a power unit of the modified type shown in Figure 4.

Figure 8 is a detail sectional view throu h the four-way valve which is employed in t e air control system shown in Figure 7; and

Figure 9 is a detail sectional view showing one of the locking devices for normally holding the bed locked in horizontal position.

The car bed 12 and the under body or frame 13 that supports it may be of any desired construction, and the bed may be mounted on the under body to swing either about centrally located fixed pivots or upon laterally disposed rocking supports, but in the accompanying drawings I have chosen to illustrate my improvements applied to a car having the latter construction. The under body 13 comprises two longitudinally disposed I beams 14 which constitute the'center sill of the under body. This center sill is mounted on trucks of any conventional type which have the usual bearing support on the ends of axles 15 on which the car wheels 16 are mounted. At two or more points spaced along the length of the car, heavy frame members 17--17 extend laterally from the beams 14 to form supports on which the tilting bed 12 rests. The upper edges of such frame members are formed with seating recesses or notches 18 adapted to receive rocker pins 19 which are carried by brackets 21 secured to the under side of the bed 12. These rocker pins and sockets form two laterally disposed rocking fulcra, around which the bed has tilting movement to either side, as illustrated in dotted lines in Figure 1. The supporting members' 17 are preferably arranged in pairs to engage with the oppo-y sitely projecting ends of the associated rocker pin 19 on each side of the bracket 21, as shown in Figure 2. A reinforcing bar or strut 22 extends across the upper edges of the sill beams 14 and ties the upper edges of the supporting frame members 17 together.

The car body 12 comprises any suitable construction of floor 23 mounted on longitudinally extending sill rails 24. Transversely extending bars 25 reinforce the frame of the bed at the ends and intermediate portions thereof. The rocker brackets 21 are secured to closely disposed pairs of these transversely extending bars 25. At opposite sides of the bed are mounted two side gates 26, pivoted adjacent to their lowerA margins on pivot pins 27 carried by the side margins of the bed, so that such gates may swing outward and downward as illustrated in dotted lines in Figure 1. Any suitable construction of gate operating mechanism may be employed for automatically swinging the gate at the dumping side of the car outwardly and 'downwardlyin a dumping operation, the construction disclosed in my copending application Serial No. 169,465, filed February 19, 1927, being typical of one construction of gate operating mechanism which may be employed.

Referring to Figure 1, the operation of tilting the bed to the right hand side is performed by a pneumatic power unit 28 which is supported on the left hand side of the car, and correspondingly the operation of tilting the bed to the left hand side is performed by a pneumatic power unit 28 which is supported on the right hand side of the car. As will presently be explained, each of these power units comprises cooperating cylindrical members, and it will be observed that they extend longitudinally of the car,

whereby the members thereof can be made relatively long and a long operating stroke 37 obtained. Associated with each power unit are motion transmitting levers and links which translate the endwise expansive movement of the cylindrical members thereof into a bed tilting movement lfor rocking the bed about the opposite rocker axis 19. The power units at the opposite sides of the car,.together with the levers and links associated therewith, are of duplicate construction, and` hence it will only be necessary to describe one of them in detail.

Referring to Figures 2 and 3, each power unit comprises two telescopically movable cylindrical members 28a and 28?), the inner y member 285 constituting a piston for operating within the outer member or power cylinder 28a. The inner head of the piston 28?) is preferably provided with any suitable packing ring 29 for preventing leakage from the chamber area 31 defined between the ends of said cylindrical members. The pneumatic power unit as an entirety has a floating or suspended support between two bell crank levers 32a and 326, which are pivotally mounted on the under body 13. The ends of the power cylinder and piston have pairs of spaced pivot ears 33 extending therefrom (Figure 6) which engage over the4 bell crank levers for pivotal connection thereto at 34. Each of these bell crank levers .consists of two correspondingly shaped plates which are spaced apart but joined rigidly at the pivot points of the lever so that such plates form a single lever unit. The pivot pin 34 extends through both pivot ears 33 and through both sides of the associated lever. The upper arm of each bell crank lever has a transversely extending pivot pin 35 which extends through a lug or ear 36 projecting from the end of a horizontal shaft 37. Both levers 32a and 325 are pivotally connected to the opposite ends of the shaft 37 Such shaft is journalled adjacent to its ends in bearing brackets 38 which extend laterally from the' sill beams 14, the brackets engaging over reduced bearing portions 39 which form, shoulders for holding the shaft against endwise shifting. The upper surface of the shaft is cut away, as indicated at 41, to clear the ends of the transverse bars 25 of the bed frame. It will be observed fromthe foregoing construction that the power unit 28 together with its two bell crank levers 32a and 325 has suspended mounting on the ends of the rotatable shaft 37, whereby such power unit and levers can swing inwardly and outwardly with respect to the under body in the operation of tilting the bed. The mounting of the bell crank levers on the ends of the shaft 37 thus provides for pivotal movement of the levers on transverse "axes, corresponding to the pivotal axes of the pins 35, and for pivotal movement about a longitudinal axis, corresponding to the rotative axis of the shaft Extending through each bell crank lever, intermediate the

pivots

34 and 35, is a pivot pin 42 on' which is mounted the lower end of a lifting link 43. Such links extend diagonally upwardly and outwardly from the levers 32a and 326, and have their upper ends pivoted at 44 on bearing members 45 which are rockably connected to the underside of the bed 12. Each link 43 preferably consists of two parallel link bars pivotally mounted on the pin 42 adjacent to the side plate of the bell crank lever, such link bars forming in eifect a single link. The upper ends of such link bars engage over opposite sides of the hanger bearing or clip 45, the pivot pin 44 passing through such bearing member and through both links. Each bearing member 45 has rocking bearing support between two spaced brackets 46 which extend downwardly from the floor of the bed. The ends of the bearing member 45 have longitudinally extending bearing pins 47 which are ournalled in the brackets 46. Thus the bearing members 45 can rock axially with respect to the bed, similarly to the axial rocking of the shaft 37 with respect to the under body, thereby accommodating the change of angle of the linkage between the bed and the under body in a dumping operation. Referring to the dotted line position shown in Figure l, it will thus be seen that in the operation of tilting the bed to either side, the power cylinder which is energized, together with its operating linkage, will swing about the

longitudinal pivot axes

37 and 47, respectively, the cylinder having a translational or bodily swinging movement so that the cylinder and linkage will remain in the same plane relatively to one another during the entire tilting operation. By such action, the tilting forces transmitted from the cylinder to the bed act at all times in a straight line, thus avoiding any sidethrust or other stresses which would ltend to cause binding of the parts and a consequent loss of operating energy.

Attention is called to the fact that the design of each bell crank lever 32a, 326 and the relation of the

pivots

34, 35, 42 and 44 is such that at the beginning of the tilting operation the cylinder exerts a relatively large lifting force on the bed, moving the same with a comparatively oslow speed, and that as the bed moves upwardly to the angle where dumping is occurring the cylinder exerts a lesser lifting force on the bed but moves the same with an increased speed. Such follows from the fact that during the initial part of the tilting operation the pivot 34 is swinging through the most effective part of its arc for transmitting power to the bell crank lever, and the pivot 42is swingingthrough that part of its arc where it can exert a'large lifting force on the link 43. Then the bed is in dumping position these pivots are moving through those port-ions of their arcs where the same degree of endwise movement of the cylinder transmits an accelerated motion to the bed. This varying ratio of power and speed is of decided advantage because it enables a maximum power to be exerted on the bed at the beginning of the tilting operation, when most of the power must be expended for lifting the bed and the load, and it affords an accelerated motion for obtaining a high angle of dump after the cylinder is relieved of part of the weight of the load. Such enables the length of the cylinder stroke and the length of the cylinders to be reduced to a minimum.

It will, of course, be understood that when compressed air is admitted to the cylinder area 3l between the head ends of the two cylindrical members 28a and 286, both members are caused to move outwardly towards the opposite ends of the car in a relative separating movement. Thus au equal lifting effort is transmitted from each of said members to its respective lifting link 43 so that equal lifting forces are transmitted to both points of Ythe bed. In practically all instances this will result in both ends of the bed tipping upwardly at a uniform speed. However, it may he desirable to provide motion equalizing mechanism so as to compel both ends of the bed to move upwardly at the same rate, even though one end of the bed is carrying a much greater load than the other end. One embodiment of this equalizing mechanism is shown in Figure 5. It comprises two meshing segment gears 48a and 486,which are supported on pivots 49 carried by the intermediate portion of the rock shaft 37. Arms extending downwardly from these segment gears carry pivot pins 5l to which are connected links 52a and 526. The opposite ends of these links are pivoted at 53 to their respective bell crank levers 32a and 326. By the provision of such equalizing mechanism it will be evident that any tendency of one bell crank lever to swing upwardly at a more rapid rate than the other lever is prevented through the coaction of the gears 48a and 486, which compel both levers to swing at the vsame rate of speed. Another alternative form of equalizing mechanism (not shown)` consists of a link which is pivotally connected at one end to one bell crank lever at a detinite radius above the fulcrum pivot 35 of such lever, and is pivotally connected at its other end to the other bell crank lever at the same radius below the fulcrum pivot of such latter lever. Such a link will obviously compel both levers to move at a uniform speed.

, Referring to Figure 6, the air for operating these power units is usually obtained from the train line pipe 54 which extends longitudinally from end to end of the car and which is adapted to be coupled through the train line pipes of the preceding carsv with the compressed air reservoir on the locomotive. If desired, the compressed air may be admitted directly from the train line pipe to the power cylinders, under the control of suitable valves, but I find it preferable to give each car a reservoir capacity for holding a reserve charge of air. To this end I have utilized the inner or piston members 286 of each power unit as air storage reservoirs, it

being noted from Figures 3 and 6 that each i of these inner piston members is constructed as a hollow cylinder, closed at both ends, for forming a reservoir 55 therein. In this regard it will also be noted that the snug tit of the inner or piston member within the r outer or cylinder member, throughout the entire lengths of both members of the power unit, minimizes the leakage of air from the working area 31 at the head end of the cylinder. Tapping into the outer end of each reservoir 55 is a pipe 56 which connects -through a flexible hose 57 with a manifold pipe 58. The viiexible hose connections 57 permit of the endwisereciprocating movement of the piston members 285. A pipe 59 branches 0E the train line pipe 54 and connects to the manifold pipe 58 through a T fitting 61.' A suitable check valve or pressure regulating valve 62 may be interposed inthe pipe 59 for preventing return flow from the yreservoirs to the train line pipe and, where desirable, supplying a reduced pressure from the train line pipe to the rescrvoirs. Branching oi the pipe 58 through aT connection 63 is a pipe 64C which connects with a manifold pipe 65. From this latter pipe the air is admitted to the chamber areas 31 of both power units under the selective kcontrol of

individual valves

66 and 66 which connect to pipe 65. Extending from one of the ports of each of these valves is a flexible hose 67 which connects with a pipe" 68 tapping into the head end of t-he outer or cylinder member 28a, the flexible hose connection 67 permitting the endwise operating movement of such outer cylinder. The valves 66-66 are any conventional types of threeway valves, having 'a rotatable valve element operable to place the flexible hose connection 67 in communication selectively either with the air supply pipe or with an exhaust port 69 leading from the valve. It will be evident that in one position of such valve element, compressed air is admitted to the power cylinder controlled by such valve, and in the other position of said valve element this air supply is cut oi' and the cylinder is opened to the atmosphere through the port 69, for exhausting the cylinder.

Referring to Figure 2, each of such valves has its rotary valve element connected to an operating rod 71 which extends to the end of the car where it is provided with an operating handle 72 for rotating the rod and valve element to the dierent control positions of the latter. Each valve operating rod 71 has suitable bearing support in bearing brackets 73 and 7 4, carried on the under frame structure of the car.

To prevent the inertia of the bed and of the load carried thereby from causing the bed to tip outwardly on the under body when the car is rounding a curve, it is desirable that suitable locking devices be provided which will normally lock the bed against tilting movement. Preliminary to a dumping operation, such locking device associated with the rising side of the car bed must, of course, be released to permit the bed to tilt to dumping position. I have provided a novel arrangement of locking devices which are associated directly with the control valves 66-66, so that the proper locking device is released automatically when one of said valves is operated for causing the corresponding side of the bed to be tilted upwardly. These locking devices consist of hook-shaped arms 76 which are tixedly secured to each of the valve operating rods 71. The hook ends of these arms are adapted to engage over the rocker pins 19, which are carried by the bed. As shown in Figure 2, the rocker pins 19 at the valve control end of the car are extended considerably beyond the sides of their respective brackets 21, to dispose a portion of each rocker pin in position to be engaged by the associated locking hook 76. The outer end of such rocker pin may have reinforcing support in a bracket 77 extending downwardly from the bed. It will be evident that the engagement of the hooks 76 over the rocker pins 19 at each side of the bed will positively hold the bed locked against tilting movement to either side. Upon the operation of the valve control rod 71 at either side of the car, to cause this side of the car to move upwardly in a dumping operation, the hook 76 which is mounted on such valve control rod will be released from the rocker pin 19 simultaneously with or just prior to the opening of the valve 66 or 66', thus unlocking this side of the bed for upward swinging movement. That is to say the angular relation between each hook 76 and the valve element in the corresponding

valve

66 or 66 is such that the hook will be completely disengaged from the rocker pin 19 before air is admitted to the corresponding cylinder 31. When the bed is returned to its normal position, the act of restoring the valve to its closed position'through o eration ofthe t rod 71 will swing the hook 76 ack into locking engagement over the rocker pin 19.

In the construction thus far described the bed returns to its normal position under the action of gravity when the power cylinder is vented to the atmosphere. In Figure 7 I have illustrated a modified construction of power unit which may be employed for obtaining a power return of the bed to its normal position. In this construction the inner or piston member is formed witha reduced trunk portion 79 of smaller diameter than the interior of the outer or cylinder member. A iiange 81 on the head end of said trunk portion constitutes the piston head for the inner or piston member, and secured to opposite sides of such flange are suitable packing rings 82 and 83. The trunk portion 79 extends through an opening in a closure plate 84 which is bolted to the ianged rear end of the outer, or cylinder member, and attached to such closure plate is a packing ring 85 which contacts with the trunk portion 79. The annular chamber area 86 deined between the piston head 81 and end plate 84 constitutes a working cylinder which serves to return the two members of the power unit to their normal positions. In this embodiment the compressed air may be admitted selectively either to the lifting chamber 31 or to the return chamber 86 through a four-way valve 87. This valve, shown in detail in Figure 8 comprises four radial valve ports which are adapted to be placed alternately in communication with each other through two valve passages 88 and 89 formed in the rotary valve element 90. The supply pipe communicates with one of these valve ports and the flexible hose connection 67 communicates with another port at right angles thereto, similarly to the arrangement of the three-w'ay valve 66. The third port 91,` which is alined with the supply pipe 65, constitutes the exhaust outlet for the valve, and the fourth port, which is alined with the hose connection 67, is connected to a pipe 92 which leads to the bed return cylinder 86. A flexible hose 93 is interposed in the pipe connection 92 so as to permit of the endwise movement-.of the outer cylinder section 28a. It will be observed that by actuating the valve element 90 to place the air supply pipe 65 in communication with the hose connection 67, air will be admitted to the working area 31 of the cylinder, and that, correspondingly with this position of the valve element 90,'the pipe 92 will be connected to the exhaust port 91 so that the air remaining in the return chamber 86 will be vented tothe atmosphere, thereby avo-iding any trapping of the air in such return chamber. For restoring the bed by power, the valve element 90 is rotated to place the air supply pipe 65 in communication with the pipe 92, which transmits the compressed air to the return chamber 86, where the air is effective on the rear side of the piston head 81 for compelling the two members of the power unit to move together for returning the bed to normal position. With the valve element 90 in this latter position, it will be noted that the hose connection 67 is placed in communication with the exhaust port 91 so that the air remaining in the lifting chamber 31 will be freely vented to atmosphere. By rotating the valve element to present the relatively wide, solid portion 94 thereof to the air supply pipe 65 the admission of air is out olf from both ends of the cylinder. Attention is directed to the fact that the valve passages 88 and 89 are so arranged that when the solid or closing portion 94 of the valve element is in position to close olf the air supply pipe 65, both valve passages 88 and 89 maintain a vented communication between the exhaust port 91 and the two

cylinder areas

81 and 86. Thus there is no possibility of an accumulation of pressure building up in either cylinder area through leakage of the valve 87 which, in the case of the cylinder area 31, might cause accidental dumping of the bed.

In the foregoing construction the reduced trunk portion 7 9 still serves as an air reservoirv55 for the dumping mechanism.y Figure 7 shows only one of these power units and its piping connections, but it will be obvious that the other unit will have a duplicate valve 87 and pipe connections 91-92, similarly to the arrangement shown in Figure 6. In each of the constructions shown in Figures 6 and 7 the rapidity of descent of the bed can be regulated by manipulation of the control valve so as to prevent the bed from dropping back upon the under bod .with a jar. In the construction shown in Figure 6 such regulating action is obtained by controlling the rate of discharge of the air from the chamber area 31 to the atmosphere; and in Figure 7 the same regulating function is obtained by controlling the rate of admission of compressed air to the return chamber 86. With the bed restored to normal position, such return chamber can be vented to atmosphere through the outlet port 91 of the valve. The two reservoirs 55 store sufficient air to effect a complete dumping operation of the bed, so that the bed can be operated even when uncoupled from the train.

So far as I am aware, it is broadly new to provide bed tilting mechanism for dump cars wherein the power cylinder itself mov as a part of the operating impulse, and therefore constitutes a part of the power transmission mechanism. I also believe it to be broadly new to utilize a part of the power transmission mechanism as a reservoir for compressed air that may be employed to effect the tilting of the bed; and to provide a combined cylinder and 'reservoir for the 1pur ose described. The appended claims s ou d therefor be construed accordingly.

What I claim as my invention and desire to secure by Letters Patent is 1. A dump car comprising an under body, a tilting bed mounted thereon for tilting about laterally spaced fulcrums, and power transmission mechanism comprising a longitudinally disposed cylinder movable to tilt the bed.

2. A dump car comprising an under body, a tilting bed mounted thereon for Itilting about laterally disposed fulcrums, and mechanism for'tilting said bed comprising a longitudinally disposed power cylinder movable as a part of the operating impulse for tilting said bed.

3.' A dump car comprising an under body, a tilting bed mounted thereon, a power cylinder extending longitudinally of the car and movable endwise relatively thereto, and pivoted linkage for translating the endwise movement of said cylinder into tilting movement of said bed.

4. A dump car comprising an under body, a tilting bed mounted thereon, a power cylinder, a piston operating therein, said cylinder and said piston both having reciprocable movement relative to said car, and means operative by relative movement between said -cylinder and piston to tilt said bed.l

5. A dump car comprising an under body,

a tilting bed mounted thereon, a power cylinder reciprocably supported on said dump car and link mechanism connecting said cylinder with the bed to tilt the latter by movement of the cylinder relatively to the under body, said linkv mechanism supporting sa1d cylinder.

6. A dump car comprising an under body, a tilting bed mounted thereon, a power cylinder and a ,cooperating piston both reclprocably sup-ported on said under body, and means operatively connecting said cylinder and said piston with said bed to tilt the latter.

7. Adump car comprising an under body, a tilting bed mounted thereon, a power unit for tilting said bed, mounted on said. under body, said power unit comprising two telescopically movable cylinder members both reciprocably supported on the car, and devices connected with said members respectively and operable by movement thereof to tilt the bed.

8. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said bed comprising a power unit disposed longitudinally of the car below the bed and having translational swinging movement in connection with the tilting of the bed.

9. A dump car comprising an under body, a tilting bed mounted thereon, a reciprocable power cylinder mounted below the bed and operatively connected to tilt the bed., and supporting means for said cylinder permitting lateral swinging movement thereof in connection with the tilting of the bed.

10. A dump car comprising an under body, a tilting bed mounted thereon, mechanism for tilting the`bed comp-rising a lever pivotally supported upon said under body, and a power cylinder operatively connected with said lever and arranged to swing bodily therewith about the pivot axis otl said lever.

11. A dump car comprising an under body, a tilting -bed mounted thereon, and mechanism for tilting said bed comprising a longitudinally extending pneumatic power unit, and linkage operatively connecting said power unit with said bed, said power` unit and linkage being mounted for pivotal swinging movement relative to said under body in the operatio-n of tilting said bed.

12. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said bed comprising a horizontally extending power cylinder, and linkage operatively connecting said cylinder with said bed, said cylinder and linkage being pivotally supported on said -under body for lateral swinging movement asa unit in the operation of tilting said bed.

13. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said bed comprising a longitudilnally extending power' cylinder and linkage operatively connecting said cylinder with said bed, and means pivotally supporting said cylinder and linkage on said under body Jfor lateral swinging movement, whereby said cylinder and linkage remain in a common operating plane duringl the tilting of the bed.

14. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said hed comprising a longitudinally extending power cylinder, a piston 0perating therein, motion transmitter mechaanism connecting said cylinder and said piston with said bed, and means pivotally supporting said cylinder, said piston and said motion transmitting linkage on said under body for swinging movement about a longitudinal axis, whereby the lifting forces transmitted from said cylinder to said bed act in a single plane which swings about said longitudinal axis in the tilting movement of the bed.

15. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said bed comprising a lever, a link operatively connecting said lever to said bed, means for supporting said lever for pivotal movement in two directions about longitudinal and transverse axes, and a power cylinder connected with said lever and arranged to swing therewith about such longitudinal axis. p 16. A dump car comprising an under body, a tilting bed mounted thereon, and mechanism for tilting said bed comprising a lever, .a rocking member pivotally supported on said under body to rock about an axis extending longitudinally of the car, means pivotally supporting said lever on said rocking member, a link operatively connecting said lever with said bed, .and a power cylinder operativelyvconnected with said lever and arranged to impart bed tilting movement thereto.

17. A dump car comprising an under body, a tilting bed mounted thereon, a lever, means pivotally supporting said lever on said under operatively connected with said bed for tilting the same, and a. power unit comprising a cylinder and piston extending between and operatively connected with said levers for actuating the same by relative movement between said cylinder and piston.

19. A dump car comprlsmg an under body,

a tilting bed mounted thereon, a pair yof levers pivotally mounted on said under body and operatively connected with said bed for tilting the same, and a. power unit comprising a cylinder and piston suspended between said levers and operative by relative separating movement between said cylinder and piston to actuate said levers, said cylinder and piston swinging with said levers in their bed tilting movement.

20. A dump car comprising an under body, a'tilting bed mounted thereon, and mechanism for tilting said bed comprising a pair of bell crank levers pivotally mounted on said under body for movement about transverse and longitudinal axes, means pivotally connecting said levers with said bed, and a power unit comprising a cylinder and piston suspended between said levers and operative by rela' ive separating movement between said cylinder and piston to simultaneously operate both of said levers, said cylinder and piston swinging laterally with said levers in the pivotal movement of the latter about such longitudinal axes.

21. A dump ear comprising an under body, a tilting bed mounted thereon, power means for tilting said bed comprising a cylinder and piston, means operatively connecting said cylinder and said piston with the bed, and means for compelling said cylinder and said piston to move correspondingly throughout the bed tilting operation thereof.

22. A dump car comprising an under body, a tilting bed mounted thereon, a pair of levers pivotally mounted on said under body and operatively connected to said bed, a power unit comprising a cylinder and piston extending between and operatively connected with said levers for actuating the same by relative movement between said cylinder and piston, and means for compelling both of said levers to move correspondingly throughout the bed tilting operation thereof. i

23. A dump car comprising an under body a tilting bed mounted thereon, a power cylinder, and means for transmitting power therefrom to tilt the bed and comprising a movable air storage reservoir mounted' below said tilting bed.

24. A dump car comprising an under body, a tilting bed mounted thereon, a power unit for tilting said bed, sa'id power unit comprising two telescoping members mounted below said tilting bed and having a fluid pressure area between them, one of said members constituting a fluid pressure reservoir, means operatedby relative movement of said members to tilt the bed, and means for placing said reservoir in communication with the area between said members.

25. A dump car comprising an under body, a tilting bed mounted thereon, a pair of levers pivotally mounted on said under body and operativelyconnected with said bed for tilting the latter,- a power unit comprising inner and outer telescoping members having a fluid pressure area between them, means operatively connecting said members with said levers for actuating the same by relative movement between said members, said inner member constituting an air reservoir, and valve means for admitting the air from said reservoir to the pressure area between said members.

26. A dump car comprising an under body, a tilting bed mounted thereon, a pair of levers pivotally mounted on said under body and operatively connected to said bed for tilting the latter, a cylinder and piston, means operatively connecting said cylinder with one of said levers, means operatively connecting said piston with the other of said levers, and means for admitting compressed air to either side of said piston for tilting said bed in either direction by power.

27. A dump car comprising an under body,

a tilting bed mounted thereon for tilting about laterally disposed fulcrums, a luid pressure actuated power unit operatively connected for tilting said bed, valve means for admitting compressed air to said power unit, and locking means normally holding said bed against tilting movement and arranged to be released by movement of said valve means to open position.

28. A dump car comprising an under body, a tilting bed, rocker bearings spaced laterally from the center of said under body and supporting said tilting bed thereon Jfor rocking movement in either direction about one or the other of said rocker bearings, a pair of bell crank levers pivotally mounted on said under body at each side thereof, a fluid pressure actuated power unit at each side of the under body connected with a pair of said levers, each of said power units comprising a cylinder and piston suspended between and connected at their ends with said bell crank levers, lifting links pivotally connected between each of said levers and the bed, and valve means for admitting compressed air selectively to either of said power units.

29. A dump car comprising an under body, a tilting bed mounted thereon, mechanism for tilting said bed comprising a power cylinder, a piston operating therein, an air supply connection, and manually actuated valve means mounted on the car for admitting air selectively to either end of said cylinder, for tilting said bed in either direction by power, said valve means comprising passages normally venting both ends of said cylinder to the atmosphere when said air supply connection is closed.

30. A dump car comprising an under body, a tilting bed mounted thereon, a power unit for tilting said bed, and motion transmitting mechanism operatively connecting said power unit with said bed, said power unit being supported on and moving with said motion transmitting mechanism.

31. A dump car comprising an under body,