US3631814A

US3631814A - Hopper car closure actuating mechanism

Info

Publication number: US3631814A
Application number: US819080A
Authority: US
Inventors: William R Shaver
Original assignee: Pullman Inc
Current assignee: Pullman Standard Inc; Pullman Inc
Priority date: 1966-12-01
Filing date: 1969-04-24
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

This invention relates to operating mechanism for vehicle discharge means, and, more in particular, relates to mechanism required to open the doors of the side-type discharge hopper railroad whereby the load, such as coal, may be discharged from the side of the railroad car into rail side below car lading storage pit as it passes along a certain point of the railroad track over which it traverses.

Description

United States Patent William R. Shaver Munster, 1nd.

Apr. 24, 1969 Jan. 4, 1972 Pullman Incorporated Chicago, 111.

Original application Dec. 1, 1966, Ser. No. 598,440, now Patent No. 3,459,317, dated Aug. 5, 1969. Divided and this application Apr. 24, 1969, Ser. No. 819,080

Inventor Appl. No. Filed Patented Assignee HOPPER CAR CLOSURE ACTUATING MECHANISM 5 Claims, 9 Drawing Figs.

US. 105/290, 105/241 C, 105/251, 105/299, 214/63 Int. Cl B6ld 7/18, 861d 7130, B65d 67/24 Field of Search 105/241,

[56] References Cited UNITED STATES PATENTS 731,525 6/1903 Trapp 105/290 x 746,519 12/ 1 903 Johnson 105/25 1 758,392 4/1904 Streib 105/290 X 789,155 5/1905 Kiesel, Jr. 105/290 X 1,092,659 4/1914 Mettler 105/251 1,266,630 5/1918 Ross et al.. 214/63 1,594,863 8/1926 Warner 214/63 2,430,517 11/1947 Lunde 214/58 X 3,459,317 8/1969 Shaver 214/63 1,706,936 3/1929 Oliver 105/249 Primary Examiner-Arthur L. La Point Assistant Examiner1-1oward Beltran Attorneys-Hilmond Ov Vogel and Wayne Morris Russell ABSTRACT: This invention relates to operating mechanism for vehicle discharge means, and, more in particular, relates to mechanism required to open the doors of the side-type discharge hopper railroad whereby the load, such as coal, may be discharged from the side of the railroad car into rail side below car lading storage pit as it passes along a certain point of the railroad track over which it traverses.

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SHEET 1 [1F 5 INVENTOR WILLIAM R SHAVER PATENTEI] JAN 41972 SHEET 2 OF 5 INVENTOR' WILL/A M R. SHAVER ATT'Y PATENTED JAN 41972 SHEET 3 BF 5 INVENTOR WILLIAM R. SHAVER ATT'Y mamznm 41912 316131.814

I sum 5 OF 5 INVENTOF? WILL/AM R. SHA VER BY 9W ATT'Y HOPPER CAR CLOSURE ACTUATING MECHANISM This application is a divisional application of my copending application, Ser. No. 598,440, filed Dec. 1, 1966, now U.S. Pat. No. 3,459,317, granted Aug. 5, 1969.

The train hopper car mechanical door mechanism of the invention comprehends an unloading system that is a mechanical device, utilizing linkage powered by an off track camming device and the train motion. The door-operating mechanism has a drive crank or follower arm operating suitable linkage for opening and closing the hopper chute whereby force transfer links acting with the drive crank are operative through transverse parallelogram-type movement to simultaneously open or close a pair of opposed hopper chute doors. The engaging lever linkage mechanism on the car is movable in horizontal planes transverse to the longitudinal movement of the car. The lever linkage mechanism contacts a cam track section between the rails as the train car moves over the tothe-side and below-car lading storage pits and automatically opens the hopper car doors, holds the doors open while the coal discharges, and closes the doors after a predetermined distance. Locking of the mechanism is achieved by a pastcenter linkage and an auxiliary wedge as a safety precaution. The hopper-operating mechanism and the cam track will operate no matter which end of the car first enters the dumping area. The cam track section which is located between the rails at the unloading site has right-of-way actuating units for defining the movement of the force transfer links in accordance with the movement of the force transfer links in accordance with the movement of the car along the path of the rail.

DISCLOSURE OF INVENTION A most efficient and economical method for transporting coal is by way of railroad unitized or integral trains of hopper cars. To reduce the cost of delivering coal, a unitized train depends largely on the number of cars required, and how much time is necessary to unload the cars. Shorter unloading time produces more efficient and economical train operation. Fast discharge of coal while the train is in motion achieves minimum terminal time. Unloading systems where the overtheroad locomotive never leaves the train and the regular crew stays with the train, result in much lower cost to the user through elimination of the switch engine and special crews needed to unload cars. The inventive design incorporates features which substantially reduce the operating cost of delivering coal.

It is, therefore, a general object of this invention to provide for an operating mechanism for vehicle discharge means.

Another object of this invention is to provide for a mechanical-type unloading system utilizing linkage means powered by off track engaging device and the motion of the train.

Another object of this invention is to provide for an unloading system having a cam track section located between the train rails and operative for engagement with a lever means or follower arms on the railroad car which contacts the cam track as the car moves past the railroad side pit resulting in automatic opening and closing of the hopper railroad car doors.

Another object of this invention is to provide for a train hopper car mechanical door mechanism which is provided with a past-center linkage and an auxiliary wedge means for locking of the mechanical door mechanism as a safety precaution.

It is still a further object of this invention to provide for a door opening mechanism having a drive crank operating suitable linkage for opening and closing the hopper chute door, whereby force transfer links acting with the drive crank are operative through transverse parallelogram-type movement to simultaneously open or close a pair of opposed hopper chute doors.

Another object of this invention is to provide for a novel door-operating rail or track located between the railroad tracks, the door-operating rail means comprising a right-ofway actuating mechanism for defining the movement of the force travel links driving crank or mechanism in accordance with movement along the path of the right-of-way actuating mechanism.

These and other objects will become more apparent from reference to the following description, appended claims and attached drawings wherein:

FIG. 1 is a perspective view of a car provided with a novel door-opening mechanism;

FIG. 2 is a plane view of portions of the car employing the novel operating mechanism for the hopper car discharge means;

FIG. 3 is an upright perspective view of the components of the novel operating mechanism for the hopper car discharge operation;

FIG. 4 is a top plan view of the operating mechanism of FIG. 3;

FIG. 5 is an upright view of the hopper door opening mechanism taken along line 5-5 of FIG. 2 with the hopper doors in the closed position;

FIG. 6 is a view similar to FIG. 5 but with the hopper doors not being in the closed position, but in the fully opened position;

FIG. 7 is illustrative of a representation of the right-of-way actuating mechanism including the track and its path for placing the hopper doors in the fully open position and then placing the hopper doors in the fully closed position.

FIG. 8 is a perspective view of a modification of the device, and

FIG. 9 is still another view of a further modification of the device.

With reference now to the drawings and in particular to FIG. 1, there is shown a side discharge hopper car 2 for carrying coal or the like which is provided with the usual trucks 4 and 6 which carry the car body 8 provided with coupling means 10 and a ladder 11 and the underneath discharge hopper means 12 which comprise a pair of

similar hopper units

14 and 16. As seen more clearly in the top plan view of FIG. 2, each

hopper unit

14 or 16 comprises a pair of laterally spaced V-shaped hopper chutes I5, 15. Each hopper 15 (see FIGS. 3, 4, 5 and 6) is V-shaped in cross section and is of the side discharge type in that it is provided with a longitudinally extending laterally disposed underside sloping hopper door 18 which in the open position, as for instance shown in FIG. 6, is to permit any lading, such as coal, to be discharged laterally of or out of the side of the car and somewhat outwardly of the rail track over which the car traverses, for instance outwardly of the track 20 as schematically indicated in FIG. 1 and also as shown in FIG. 7, the track 20 consisting of two

parallel rails

21 and 22 respectively. Each hopper 15 in addition to having a movable laterally outwardly opening door 18 has an inward longitudinally extending side 24 to form with the door 18 the V-shaped hopper unit 15, having the usual end walls 26.

As the coal car traverses along the track 20 it encounters door-actuating mechanism in the form of right-of-way structure positioned between the

rails

21 and 22, generally indicated as right-of-way or door-tripping mechanism 30, as shown in FIG. 7, which mechanism 30 in turn operates the door operating or actuating lever linkage mechanism 32 located on the car itself as distinguished from the mechanism or cam track section 30 which is located on the railroad bed. When engagement occurs between the structures 30 and 32 during car movement, the door structure 18 is caused to be opened and later to be closed. The actuating device or rightof-way structure 30 for the doors comprises a pair of track or

guide section

34 and 36 spaced longitudinally of one another on the track bed, the rightof-way element 34 comprising a small initiating portion 340 which is at a slight inward sloping angle to the

railroad rail elements

21 and 22. The next part of the right-of-way element 34 consists of an elongated track or guide portion 3417 which is parallel to the railroad

track ele ments

21 and 22 and a right-of-way element portion 34c connects with the portion 34b between the

track elements

21 and 22 and is at an angle thereto and extends toward the element 22. The next right-of-way portion 34d, connecting with part 34c, is parallel to the

track elements

21 and 22. The right-ofway element 35 which immediately follows the element 34, and separated therefrom, comprises an initial portion 35a which begins where element portion 34d left off and is spaced laterally from and slightly from it toward the track element 22. The right-of-way element 35 has for its next portion a diagonal portion 35b that extends toward the outside track element 21; and the last right-of-way portion 350 is parallel to the track element 21. These right-of-

way elements

34 and 35 operate the door as will be later explained. Immediately following the right-of-

way elements

34 and 35 are the hopper-closing rightof-

way elements

36 and 37. The right-of-way element 36 is between the

track elements

21 and 22 and is a mirror image (or inverse) of element 34 having an initiating closing section orportion 36a diagonal to and extending away from track 22 followed by an elongated section 36b that is parallel to the

track elements

21 and 22, followed by a diagonal portion 36c extending toward the track element 21, followed by the last right-of-way element portion 361 which is parallel to

track elements

21 and 22. Immediately following this element 36 is the element 37 (a mirror image or the inverse of element 35) which has a portion 37a parallel to

track elements

21 and 22 and away therefrom toward rail 21, followed by a portion 3711 which diagonally extends toward track 22 followed by a last portion 370 that is parallel to both

track elements

21 and 22. As mentioned, the

track elements

36 and 37 provide for moving of the door from the fully opened position as shown in FIG. 6 to the fully closed position as shown in FIG. 5, the operation of which will be explained later.

The mechanical door-operating mechanism 32 that is actuated by actuating mechanism or right-of-way structure 30, as seen in FIGS. 2 through 6, comprises a force-actuating bar or drive lever means 40 which has an elongated follower arm 42 which carries at its ends roller means 44 and 46, the roller means 46 engaging the inside of the right-of-way element portion 34b of the element 34 (FIG. or the roller means 44 engaging the outside of element portion 35b of element 35 (FIG. 6) while the roller means 44 and or 46 is out of contact with any other right-of-way elements. The central portion of the ever 42 fixedly carries on its upper side an upwardly projecting stub shaft or arm 47 which is fixedly coupled to one end of a transversely extending upwardly disposed throw arm 48 which has at its outer lateral end an upwardly extending pin 50 which pivotally connects with the door-opening rod 52 by enlarged loose-fitting rod aperture 52a for opening the hopper 18 on the right side of the hopper car. Above this the pin 50 also extends through enlarged loose-fitting aperture 54a of the force transfer link 54. The

apertures

52a and 54a have such sufficiently loose fit with respect to the pin 50 as to allow them to be freely pivoted with respect to the pin and in particular the force travel link 52 is not only permitted fore-andaft and transverse motion but is also permitted to have vertical motion for swinging open the door 18. The other end 55 of the link 52 is pivotally attached to a pin 56 attached to the door 18 for opening the door. An intermediate motion transmitting arm 58 is connected to the pin 50 at its end 59 and at its other end 60 has a pin connecting the interconnecting arm 58 with the crank arm or throw arm 62 at the end 63 of the arm 62, the connection being made by the vertically extending pin 64 which receives the other door-operating rod 52 having an end 55 connected to a pin 56 for opening the other laterally opposed door 18 on the left side of the car. The last-mentioned rod 52 is suitably enlargedly apertured at 52a and below the door-opening rod 52 is disposed the other longitudinally descending force transfer link 54 which is suitably enlargedly apertured at 540. The crank arm 62 at its end 65 has an upwardly extending shaft 66 freely jour'naled in journal block 67 in the underside member 68 attached to the center sill structure 69 of the hopper car. A support structure 70 suspendingly carries and provides a bearing arrangement for the members 47 and 65 of the lever system. Thus it is seen that the crank

arms

48 and 62 are interconnected with one another by the link 58, the link 58 being so connected to each crank

arm

48 or 62 that the force-activating follower bar or drive lever 42, the

crank arm

48 and 62 and the crank lever 58 at all times have their longitudinal extents lying in a common vertical plane as they are rotated by engagement of the

rollers

44, 46 with the camming rail means 34, 35, 36, 37. As the cranking structure which consists of

elements

62, 58 and 48 rotate about their pivot 66, the left force transfer link 54 moves to the right to take the position held by the right force transfer link 54 and the right transfer link 54 simultaneously moves to take the place of the left transfer link 54 with concurrent pulling on the respective door-opening

rods

52, 52 to open the respective laterally disposed hopper doors l8, 18. A 180 rotation of the follower bar 42 is required to move the respective force transfer links 54, 54 to take each other's position moving the doors from fully closed position as shown in FIG. 5 to the fully opened position as shown in FIG. 6 to the fully closed position again. Either end of the car can enter the right-of-way track elements for dumping of the lading. It will be noted that when referring to FIG. 7 the track right-of-way element portions that are parallel to the

rails

21 and 22 do not aflect the action of the force-actuating bar or drive lever but that the camming portion of the right-of-

way elements

34, 35, 36 or 37 cause movement of the transfer or force transfer links in a transverse direction. In reviewing FIG. 7 it is seen that as the drive lever roller 46 engages right-of-way element 34b the drive lever 42 position remains unaffected but as the lever roller engages the right-of-way element 340 it is caused to rotate about the pin 46 in a direction with its lower end roller 44 moving toward the right-of-way structure 34; whereupon continued movement of the car in the direction of the arrow causes the drive lever 42 to move in a position parallel to the train tracks 21 and 22 in which position the hopper doors are half open and as the car continues forward the other roller 44 engages the outside of the right-of-way track 35 and causes the drive lever 42 to rotate another to a position where it was rotated from its initial position and at this point the hopper doors are fully opened. As the car continues in the direction of the arrows it is seen that the drive lever roller 46 engage the inside of right-of-way structure 36 to cause rotation of the drive lever 42 in a clockwise direction as the roller 46 engages the inside of the track 36c causing the hopper doors to start to move to the closed position and when at the right-of-way element portion 361 the doors are partially closed and then the roller 44 engages the outside of the portion 37b to cause the drive lever 42 to rotate another 90 to its original position where the hopper door is in the fully closed position.

With reference to FIG. 2 it is noted that the force transfer links positioned to be coupled to the longitudinally intermediate door-opening

rods

52, 52 similarly connected to foreand-aft cross transfer members 58 and door-opening

rods

52, 52 for opening additional fore-and-aft hopper car doors. In this respect it will be appreciated that the follower bar 42 could be placed in the center of the car as shown in FIG. 2 or at some other point along the car, say, at the point where the rearwardly disposed door-opening rods are located or at a point where the forwardly disposed dooropening rods are located. Each door-opening rod 52 is provided with a turn buckle or adjusting threaded collar 71 (see FIG. 3) to decrease or increase the overall length of a respective dooropening rod 52 for adjusting the degree or amount of opening or closing of the hopper door. Similar type of adjustable means for extending or decreasing the length of the force transfer links may be provided for determining the amount of degree of opening of the hopper doors. The adjustable means 71 in the door-opening rods 52 take up tolerances and insure a tight closing of the door. The

enlarged holes

54a, 52a in the force transfer links 54 and the door-opening rods 52 at their connection with the crank portions are oversized to allow for transverse and longitudinal movement as well as vertical motion. The actuating

rail pickup wheel

44 or 46 contacts actuating rail members at the lading dumping pit along the side of the rail.

It is to be noted that in FIG. 4 and in FIG. 2 there is provided within the housing 70 an overcenter stop 75 and this is also shown in FIGS. 5 and 6. This overcenter stop prevents accidental opening of the doors when the doors are in the closed position because if the doors try to open, the crank arm 62 is pulled against the overcenter pin 75 to prevent any further opening of the door, as shown in FIG. 4. This arrangement of the overcenter pin operates in either direction the train is running. In the open position of the door, the door is kept open by the door-operating

rods

52, 52.

It is thus seen that there is provided a novel side discharge hopper door for a railroad car, said novel door-operating mechanism including a drive crank assembly connected with force-transmitting linkage for operating door-opening rods, whereby the drive crank is driven by a drive lever having driving engagement with a right-of-way mechanism in the form of an actuating rail structure.

A modification of the dooroperating mechanism and rightof-way actuating track or rail therefor is shown in perspective in FIG. 8 where there is provided a door-operating mechanism 80 for operating the

doors

18, 18 of the car. The door-operating mechanism comprises the parallel force-transmitting

members

82,82 which are constrained for rotation with the drive levers 84a,

84b having rollers

86,86 engaging the rightof-way track or rail means 88 (which is similar to FIG. 7 but at a more acute angle in cross section) whereby the drive lever 84a is swung to the right, rotating the force-transmitting member in a counterclockwise direction which similarly rotates slotted coupling arm 90 having a slot 91 coupling with a pin 92 in pin-carrying arm 94. The arm 94 is caused to rotate clockwise by the arm 90 which in turn causes the other forcetransmitting member 82 to rotate in a clockwise direction whereby throw arms 82a and 82b are caused to rotate by rotation of their respective force-transmitting

members

82, 82 to cause their respective door-opening rods 96a, 96b to open the

doors

18, 18. It is to be noted that each of the door-opening rods or links 96a or 96b have a U-shaped arm portion 97 to provide sufficient angular movement of the rods 96a or 96b in order to open the hopper doors l8, 18. The links 96a or 96b may be attached to each side or to the center of each door. This arrangement permits operating of both of the force-transmitting members or shafts together. The drive lever 84b permits the opposite end of the car to operate should the car be turned about. The actuating track 88, of course, is located as in the first-disclosed embodiment at the unloading site.

A further modification is shown in FIG. 9 where there is shown the right-of-way track 100 engaging the roller 102 of the drive lever 104 to rotate shaft or force-transmitting member 106 in a counterclockwise direction to rotate the crank arm 108, the outer ends of which carry

respective dooroperating rods

110, 112 for opening the

doors

18, 18. The drive lever or lock-actuating arm rotates about the operating shaft or force-transmitting member 106 to rotate the crank arm 108 thereabout in order to swing the looped or bight formed ends 112 of each of the door-operating

rods

110, 112, say, from 90 to, say, 100 swing of the drive lever or lock-actuating arm 104. As usual, the actuating track 100 is located at the unloading site. The track 100 is curved to open the doors, hold the doors open during loading, and lock the doors after unloading. Thus, it is seen that the first-mentioned embodiment provides that the drive lever and its associated crank mechanism rotates about a vertical axis and its associated force transfer members move transversely in a horizontal plane whereas in the second and third embodiments, aforementioned, the drive lever swings about a horizontal axis in a vertical plane and the force transfer members or member rotate or rotates about horizontal longitudinal axes or axis. In all three instances, however, the door-operating rods, of course, move vertically in a vertical plane transverse to the longitudinal axis of the car. It is thus seen that there is provided drive lever means extending below the vehicle tracks and couplable through force-transmitting means with door opening or operating rods that move in transverse vertical planes wherein there is a throw arm or crank ann connection between the drive lever and the force-transmitting member or means.

The foregoing description and drawings are given merely to explain and illustrate the invention, and the invention is not to be limited thereto, since those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.

What is claimed is:

1. Door-operating mechanism for a vehicle discharge means having laterally opening doors for discharging a load laterally outward of the vehicle, comprising:

a door-operating mechanism having downwardly projecting dooropening drive lever means for engagement with a road-mounted rail means over which the vehicle traverses,

a pair of longitudinally extending laterally spaced-apart force-transmitting members mounted on the vehicle,

lost motion connection means extending transversely on said vehicle and having a lost motion connection with each of said force-transmitting members,

a pair of door-operating means, one of each having a connection with a respective force-transmitting member and extending laterally therefrom and adapted for connection with a respective vehicle discharge means door,

said drive lever means having a throw arm connection with at least one of said longitudinally extending force-transmitting members for operating each of said door-operating means in vertical laterally extending plane attendant to opening and closing each of said doors,

said drive lever means comprising a depending lever, the lower end of which is provided with rail-engaging means and the upper end of which is mounted with a force-transmitting member for arcuate movement thereabout in a vertical plane transverse to the longitudinal axis of the car,

said lost motion connection means comprising a pair of arms,

the outer ends of each arm being connected with a respective force-transmitting member for movement thereabout in a vertical transverse plane and the inner ends of each arm being attached with one another in a lost motion couple,

and each door-operating means comprising a transversely extending link and an arm coupled at one end with the link and at the other end coupled with a respectively force-transmitting member for movement thereabout in a vertical transverse plane,

the force-transmitting members each rotating about a generally horizontal longitudinal axis.

2. The invention according to claim 1, and

road-mounted rail means adapted for operative engagement with said drive lever means,

said rail means comprising a pair of longitudinally spaced angulated rails each having a vertical face defining an angulated meandering path along which the drive lever means rides for opening of the vehicle discharge doors,

the surface of leading rail being in laterally opposed position with respect to the surface of the trailing rail.

3. The invention according to claim 2, and

second rail means being spaced from said first-mentioned rail means and comprising a second pair of rails complementary to the rails of the first-mentioned rail means and being mirror images of said first rail means,

each of the rails of the second pair being placed in reverse order for closing of said doors, whereby the first-mentioned rail means open said doors.

4. The invention according to claim 1, and

said drive lever means comprising a further arm for engagement with the track and connected with the other forcetransmitting member for opening and closing the vehicle doors when the vehicle is turned about.

5. The invention according to claim 1, and

downwardly sweeping and then arcuately upwardly sweeping surface portions to provide for rotation of said drive lever attendant to opening and closing the vehicle discharge doors.

II it I 1F I

Claims

1. Door-operating mechanism for a vehicle discharge means having laterally opening doors for discharging a load laterally outward of the vehicle, comprising: a door-operating mechanism having downwardly projecting dooropening drive lever means for engagement with a road-mounted rail means over which the vehicle traverses, a pair of longitudinally extending laterally spaced-apart forcetransmitting members mounted on the vehicle, lost motion connection means extending transversely on said vehicle and having a lost motion connection with each of said force-transmitting members, a pair of door-operating means, one of each having a connection with a respective force-transmitTing member and extending laterally therefrom and adapted for connection with a respective vehicle discharge means door, said drive lever means having a throw arm connection with at least one of said longitudinally extending force-transmitting members for operating each of said door-operating means in vertical laterally extending plane attendant to opening and closing each of said doors, said drive lever means comprising a depending lever, the lower end of which is provided with rail-engaging means and the upper end of which is mounted with a force-transmitting member for arcuate movement thereabout in a vertical plane transverse to the longitudinal axis of the car, said lost motion connection means comprising a pair of arms, the outer ends of each arm being connected with a respective force-transmitting member for movement thereabout in a vertical transverse plane and the inner ends of each arm being attached with one another in a lost motion couple, and each door-operating means comprising a transversely extending link and an arm coupled at one end with the link and at the other end coupled with a respectively force-transmitting member for movement thereabout in a vertical transverse plane, the force-transmitting members each rotating about a generally horizontal longitudinal axis.

2. The invention according to claim 1, and road-mounted rail means adapted for operative engagement with said drive lever means, said rail means comprising a pair of longitudinally spaced angulated rails each having a vertical face defining an angulated meandering path along which the drive lever means rides for opening of the vehicle discharge doors, the surface of leading rail being in laterally opposed position with respect to the surface of the trailing rail.

3. The invention according to claim 2, and second rail means being spaced from said first-mentioned rail means and comprising a second pair of rails complementary to the rails of the first-mentioned rail means and being mirror images of said first rail means, each of the rails of the second pair being placed in reverse order for closing of said doors, whereby the first-mentioned rail means open said doors.

4. The invention according to claim 1, and said drive lever means comprising a further arm for engagement with the track and connected with the other force-transmitting member for opening and closing the vehicle doors when the vehicle is turned about.

5. The invention according to claim 1, and road-mountable rail means being provided for engagement with said drive lever means, said rail means comprising a rail having longitudinally extending rail engaging surfaces, said surfaces extending also in progressively arcuately downwardly sweeping and then arcuately upwardly sweeping surface portions to provide for rotation of said drive lever attendant to opening and closing the vehicle discharge doors.