US3628771A - Scissors-type lifting linkage elevator - Google Patents

Abstract

An elevator, for example, a commercial aircraft cargo loading elevator, utilizing a scissors-type lifting linkage, wherein the variation of the lifting force required by the lifting actuator means is minimized during the entire lifting cycle by utilizing scissors-type linkage pivot means offset below the planes formed by the two frames and attaching the lifting means above the plane of one of said frames. The use of such offset center pivot means in combination with said scissors-type linkage permits a scissors linkage geometry with minimum variation in lifting actuator force during the entire lifting cycle, and with such a structure a controlled platform translation in the direction transverse to the lifting direction is accomplished.

Description

United States Patent inventors lhakon G. Egeland 7 SeIbrook Lane, Stoneybrook, N.Y. 11790;

John Dioguardi, 16 Sandy Court, Port Washington, N.Y. 11050 July 28, 1969 Dec. 21 l 97 l Continuation-impart of application Ser. No. 646,393, June 15, 1967, now abandoned. This application July 28, 1969, Ser. No. 20,443

Appl. No. Filed Patented SCISSORS-TYPE Lil-TING LINKAGE ELEVATOR 5 Claims, 5 Drawing Figs.

US. Cl 254/122, 187/18 lnt.Cl. B661 3/22, B66b ll/04 Field of Search 254/122,

Primary Examiner-Othell M. Simpson Attorney-John P. Chandler ABSTRACT: An elevator, for example, a commercial aircraft cargo loading elevator, utilizing a scissors-type lifting linkage, wherein the variation of the lifting force required by the lifting actuator means is minimized during the entire lifting cycle by utilizing scissors-type linkage pivot means offset below the planes formed by the two frames and attaching the lifting means above the plane of one of said frames. The use of such offset center pivot means in combination with said scissorstype linkage permits a scissors linkage geometry with minimum variation in lifting actuator force during the entire lifting cycle, and with such a structure a controlled platform translation in the direction transverse to the lifting direction is accomplished.

PATENTED naczl m SHEET 1 [1F 2 INVENTORJ 14:0 :0 5 f 2/00 John Olayam/ U,- Br 64/ ATTORNEY SCISSORS-TYPE LIFIING EINKAGE ELEVATOR This application is a continuation-in-part of our application Ser. No. 643,393, filed June IS, 1967 now abandoned.

This invention relates to elevators utilizing a scissors-type lifting linkage for lifting various types of aircraft cargo loads, with a hydraulic lifting and lowering means, wherein there is a load platform attached to said lifting linkage, and said platform and said scissors-type lifting linkage are at all times efficiently raised by the actuator means from their package from initial lift-off to the final height with a minimum variation in lifting actuating force or, in other words, with the actuating load on the actuatorbeing as constant as possible and accompanying simultaneous controlled platform translation in the direction transverse to the lifting direction.

Scissors-type linkage elevators are generally known and have been disclosed in such US. patents as the McCartney et al. US. Pat. 3,282,566.

In the presently known, or so-called standard type, scissorstype lifting linkage elevators of the prior art as shown, for example, by each of the foregoing patents the scissors lift arms are connected by pivot means on the line of intersection formed by the straight plane between and through the center of rotation of the platform support and the center of rotation of the base support of one arm and the straight plane between and through the center of rotation of the platform support and the center of rotation of the base support of the other arm, with the result that the lifting actuating load required at lift-off to raise the pivotally connected scissors arms and, of course, the platfonn, from the collapsed package is much greater than the lifting actuating load during the remainder of the entire lifting cycle, that is, until the platform reaches its required height. Because of the required additional lifting load at liftoff'from the package, such prior art elevators include auxiliary or secondary lifting actuators, in addition to their primary lifting actuator.

The scissors-type liftinglinkage elevator of this invention includes all the conventional or known component elements, such as the movable platform, the base member, a scissors linkage having pivotally connected arms, with said arms having support means on the platform and the base, and actuating means for lifting, and of course lowering, the scissors linkage and the platform. The foregoing problems, with particular emphasis on the development of the necessary actuating force to accomplish the initial lift-off, are solved in the elevator of this invention simply and economically by utilizing in the elevator structure, in combination with the foregoingdescribed conventional or known elements of the elevator, a pivot means for pivotally connecting the scissors linkage is positioned offset below the general planes of the frames. The two arms forming each frame have pivot elements at opposite ends thereon and each plane just referred to passes through all four pivots in each frame. An imaginary straight line connecting the pivots in each arm in one frame would pass through this plane. The pivots just referred to connecting the two pairs of frames lie below these lines. A linear actuator comprising a hydraulic piston, piston rod and cylinder assembly is connected with one of the frames at a point above the general plane of this frame. This point of attachment is located between the pivot between the frames and the load platform. The other end of the linear actuator is pivoted near the base of one of the frames. As a result, we provide means to secure an almost constant lifting force during the entire lifting cycle and simultaneous controlled platform translation in the direction transverse to the lifting direction and an actuator load at initial vNo. 3,220,585 and Clarke US. Pat. No.

, lift-off which is lower than the combined actuator loads of the primary and auxiliary actuators as used in the foregoing described prior art elevators,

One of the objects of this invention is to provide an elevator such as, for example, a commercial aircraft cargo-loading elevator, wherein the actuator load or force has a minimum variation in lifting actuating force or, in other words, is as substantially constantas possible and there is required a relatively lower actuator force or load without the need for additional auxiliary or secondary actuator means at the initial lift-off, and there is attained simultaneous controlled platform translation in the direction transverse to the lifting direction, all in a simply and economically made lifting structure.

Other objects and features will be readily apparent from the following detailed description which is not limiting but only illustrative of the preferred embodiment of this invention.

In the drawings FIG. 1 is a view in perspective of the elevator of this invention;

FIG. 2 is a diagrammatic view in perspective of the straight intersecting planes through component elements of the elevator shown in FIG. 1;

FIG.,3 is a diagrammatic showing of the elevator of FIG. 1 in various positions during the lifting cycle;

FIG. 4 is a graphical representation of actuator load in pounds versus platform travel in feet during the lifting cycle of the elevator shown in FIG. I with relation back to the diagrammatic showing of the elevator at various positions during the lifting cycle as shown in FIG. 3;

FIG. 5 shows a modification.

The scissors-type lifting linkage elevator I of this invention includes peripheral structural members 2, 4, 6 and 8 defining a generally rectangular peripheral frame or base I0. Said base 10 is shown resting on the ground, but may include bracketmounted ground-engaging wheels (not shown) for supporting it and of course the elevator adjacent to the ground for movement, as required. Cross braces I2 extend between side frame members 4 and 8, and fixedly attached to said members 4 and 8, as by welding, are channel members or tracks 14 and I6.

Scissors linkage 18 has pivotally connected inner arm 20 and outer arm 22. Outer arm 22 is pivotally connected to base I0 by pivot pins 24 and brackets 26 attached to frame-bracing channel 28 fixedly secured to and between members 4 and 8. Outer arm 22 also carries on its free end rollers 30. Load-carrying platform 32 is supported by scissors linkage l8 and is connected to base I0 by scissors linkage 18, as is clearly shown in the appended drawings. F ixedly attached to side members 34 and 36 of platform 32, as by welding, are channel members or tracks 38 and 40 for guiding rollers 30, 30 as they move therealong in the direction from rear member 42 of platform 32 toward front member 44 of platform 32 during the lifting of platform 32 from the package or collapsed position of the scissors linkage l8 and platform 32.

Vertically aligned, when the s'cissors linkage l8 and platform 32 are in package or collapsed position, with frame-bracing channel 28 is frame-bracing channel 46 fixedly secured to and between platform side members 34 and 36. Platform 32 includes a generally rectangularly shaped peripheral frame of peripheral structural members 44, 34, 42 and 36 having positioned thereon and joined thereto floor 48 having positioned therein and thereon casters (not shown) for enabling the easy movement of a load. Inner arm 20 is pivotally connected to platform 32 by pivot pins 50 and brackets 52 attached to bracing channel 46. Inner arm 20 also carries on its free end rollers 54 which are guided by channel members or tracks 14 and 16 as they move therealong in the direction from frame member 6 of base 10 toward frame member 2 of base 10 during the lifting cycle. When scissors linkage l8 and platform 32 and, of course, base 10 are in package or collapsed position, pivot pins 24 and 50, brackets 26 and 52, and rollers 30, 30 and 54, 54 are respectively in vertical alignment as are frame- bracing channels 28 and 46,

Inner arm 20 includes spaced-apart parallel members 56, 56. The upper opposite portions of said spaced-apart parallel members 56, 56 are bracedby X-brace 58, and the lower opposite portions of said spaced-apart parallel members 56, 56 are braced by X-brace 60. Secured, as by welding, to crossstrut 62 of X-brace 58 and also secured, as by welding, to cross-strut 64 of X-brace 60 is rectangularly shaped plate brace 66. Each of said members 56, 56 has, in its middle position, as an integral part thereof, a trapezoidally shaped projection 68 extending below a straight line drawn between the pivot elements at opposite ends of the arm with circular opening 70 therethrough. the centers of said circular openings 70, 70 being on the same centerline.

Outer arm 22 includes spaced-apart parallel members 72, 72. The upper opposite portions of said spaced-apart parallel members 72, 72 are braced by K-brace 74, and the lower opposite portions of said spaced-apart parallel members 72, 72 are braced by K-brace 76. Each of said members 72, 72 has, in its middle portion, as an integral part thereof, a trapezoidally shaped projection 80 extending below the general plane of the frame with circular opening 82, the centers of said circular openings 82, 82, 70, 70 being on the same centerline. The frame composed of arms 22 will hereinafter be called the first frame and that having arms 20 as the first frame.

The outer surface 84 of each member 56 of inner arm 20 is spaced apart from the inner surface 86 of each member 72 of outer arm 22, and each space therebetween is wide enough to accommodate the greater portion of a linear actuator such as one of the hydraulic rams 88 utilized for lifting platform 32 and, of course, scissors linkage 18 from package or collapsed position.

The linear actuators preferably used to lift platform 32 and scissors linkage 18 from package or collapsed position are hydraulic rams 88, 88 each including a cylinder 90 and a piston 92, each piston 92 being pivotally connected at its upper end to a shaft 94 fixedly secured in brackets 96 secured, as by welding, to the outer surface 84 of member 56 of inner arm 20. These brackets are offset above the general plane of the frame. These brackets can, of course, be side extensions of the arms shaped like the extensions 68 and 80 instead of separate elements welded to the arms. Cylinder 90 of each hydraulic ram 88 is pivotally connected at its lower end to a shaft 98 fixedly secured in a bracket 3 secured, as by welding, to crossbeam 5 secured to members 72, 72 at the inner surfaces 86, 86 thereof. This pivot 98 should not be higher than frame pivot 24 and the greater the distance it lies below frame pivot 24 the more efiicient is the hydraulic ram at initial liftoff. Fluid under pressure is supplied to said hydraulic rams as required to lift platform 32 and scissors linkage 18 by wellknown means such as, for example, electrical pump means (not shown) driven by an internal combustion engine (not shown) and suitable switch means (not shown) are used for controlling operation of said pump supplying said fluid to rams 88, 88 so that lifting and lowering platform 32 and scissors linkage 18 may be controlled both from the ground and from platform 32.

Positioned through and secured in circular openings 82 and 70 of one set of members 72, and 56, respectively, is shaft 7a, and positioned through and secured in circular openings 82 and 70 of the other set of members 72 and 56, respectively, is shaft 7b, the centers of said circular openings 82, 82, 70, 70 being on the same centerline which coincides with the centerline of said shafts 7a and 7b, said shafts 7a and 7b likewise being on the same centerline. Scissors arms 20 and 22 are pivoted to each other for movement with respect to each other on said shafts 7a and 7b.

Referring to FIG. 2, therein is shown a diagrammatic perspective view of the straight intersecting planes A and B through inner arm 20 and outer arm 22, respectively, together with trapezoidally shaped projection 80 having circular opening 82, the projection 80 and opening 82 being shown thereon for purposes of clarity only. Planes A and B are straight planes and the pivot elements 50-54 and -24 at opposite ends thereof lie in said planes. Plane A is in the plane between and through the center of rotation c of the platform support means or pivot pins and the center of rotation d of the base support means or rollers 54 of inner arm 20. The centers of rotation of the pivot pins 50 coincide and are on line c, while the centers of rotation of the rollers 54 coincide and are on line d, and lines c and d are parallel to each other. Plane B is the plane between and through the center of rotation a of the platform support means or rollers 30 and the center of rotation b of the base support means or pivot pins 24 of outer arm 22.

The centers of rotation of rollers 30 coincide and are on line a, while the centers of rotation of the pivot pins 24 coincide and are on line b, and lines a and b are parallel to each other. The line of intersection of planes A and B is line G--G and is intermediate lines a and b and lines c and d. Line F-F is the centerline through the centers of circular openings 82, 82, 70, and is ofiset from line G-G, as is clearly shown in the appended drawings. Line q of plate A is a straight line passing through the centers of rotation of pivot point 50 and the roller 54 of inner arm 20, and line r of plane A likewise is a straight line passing through the centers of rotation of pivot point 50 and roller 54 of inner arm 20. Thus it is readily apparent from the appended drawings that lines 0, q, d, r, form straight plane A. Line s of plane B is a straight line passing through the centers of rotation of roller 30 and pivot point 24 of outer arm 22, while line I of plane B likewise is a straight line passing through the center of rotation of roller 30 and the center of rotation of pivot point 24 of outer arm 22. Thus it is readily apparent from the appended drawings that lines a, s, b, 1 form straight plane B. Extensions 81 on plane A have pivot openings B and these pivot openings lie above the plane of A, above pivot 82 between the planes, and between the latter pivot and pivot 50 at the top of the plane. The hydraulic rams are connected with these pivots.

Now referring to FIG. 3, therein is set forth a diagrammatic showing of the elevator of this invention in various positions during the entire lifting cycle, namely from the package or collapsed position to the final lift position at three points of said lifting cycle, namely point 1, point 12 and point 3, the posi tions at points 2 and 3 being shown in dotted lines. The point 1 position shows diagrammatically the scissors lift arms 20 and 22 in collapsed or packaged condition. The point 2 position shows diagrammatically the scissors lift arms 20 and 22 approximately midway during the lifting cycle. The point 3 position shows diagrammatically the scissors lift arms 20 and 22 at the end of the lifting cycle. Line 2 designates outer scissors lift arm 22. Line f designates inner scissors lift arm 20. With reference back to elevator l as shown in FIG. 1, pivot pins 24 and 50 and rollers 54 and 30 are diagrammatically shown by points in FIG. 3. Line g designates the centerline through cylinder and piston 92 of each actuator or hydraulic ram 88, the respective centerlines of said actuators being on the same plane, as is clearly shown in the appended drawings. Point j designates the pivot point offset from center or. stated in other words, the intersecting line F-F (FIG. 2) offset from the intersecting line 6-0 (FIG. 2) of the straight planes A and B through inner arm 20 and outer arm 22, respectively. Links k and (designate the connecting lines between pivoting pointj and the outer arm 22 and the inner arm 20, designated by lines e andf, respectively. Now, the moment arm D is a line segment drawn from pivot] to the line of actuation or centerline g making substantially a right angle with the centerline g. The linear actuator which performs the lifting is shown in FIG. 1 as being pivotally connected at its upper end at 84 to a bracket or upward extension of the frame 20 and the lower end to the base at a point coaxial with pivot 24 of frame 22. The arrangement can be reversed as shown in FIG. 5 so that the upper end of the actuator 90'-92' is connected with an upward extension of frame 22 at 102', above the pivot 82' for the frames, and the lower end to the frame 20' adjacent roller pivot 54.

In either arrangement, the pivot axis between the frames is below the general plane of the frame and the pivot for the upper end of the actuator is above the plane of frame 20 in the preferred arrangement of FIG. 1 or above the plane of frame 22 just described. The distance of one below and the other above can be about the same and this is the moment arm. The length of the frame is about 10 times the moment arm but it may be as low as seven and as high as 13.

The rollers at the outer ends of the frames travel over trackway areas although the areas are sometimes referred to herein as trackways per se. It is clear, however, that the horizontal web of each arm in the frame presents in effect the trackway, affording smooth passage for these rollers.

The presence of the moment arm D during the operation of elevator 1 of this invention makes possible the initial lift-off without the need for any auxiliary or secondary actuator means and without the need for any additional eccentric cam and roller means at an actuator load or force relatively lower than that previously utilized in prior art elevators, with the accompanying minimum variation in lifting actuator load or force during the entire lifting cycle wherein the platform and scissors linkage is raised vertically from the package or collapsed position with respect to horizontal ground. Thus, there is here permitted a scissors linkage geometry wherein the actuator means is pivotally connected to both scissors lift arms and 22 and said actuator means is actually moved upwardly with the upward movement of the scissors linkage and platform and there is accomplished a controlled platform translation in the direction X transverse to the upward lifting direction all with a minimum variation in lifting actuator load or force duiing the entire lifting cycle. in heretofore known elevators not utilizing the herein described offset pivot means and not utilizing said ofi'set pivot means together with the herein described actuator means pivotally connected to the outer and inner scissors lift arms as herein described, such moment arm as herein shown and designated by perpendicular distance D has been absent during the entire lifting cycle making it necessary to use the aforementioned auxiliary or secondary actuator means or the eccentric and roller means to accomplish initial lift-off at an initial actuator load at lift-off relatively higher than required with the elevator of this invention and with a great variation in lifting actuator force during the entire lifting cycle, all as clearly shown in the appended drawings with particular emphasis on FIGS. 3 and 4. FIG. 4 is a graphical representation of actuator load in pounds versus platform travel in feet upwardly, of course, with respect to ground during the lifting cycle of the elevator of this invention. Line R is a plot of the actuator load versus upward platform travel of the three positions or points (points 1, 2 and 3) of the elevator during the lifting cycle, and line S is a plot of actuator load versus upward platform travel of comparable positions or points of the prior art elevators. As is readily seen at 0 feet, or in package position, the actuator force required for initial lift-off by the elevator of this invention is less than the actuator force required for initial lift-off by prior art elevators, and this because of the presence of the moment arm D at initial lift-off as well as during the entire lifting cycle. In the prior art elevator structures such a moment arm as is moment arm D is not present at initial lift-off and thus there is required an actuator load at initial lift-off greater than the actuator loads during the upward travel of the platform during the lifting cycle. At the position shown by point 1 the moment arm D in the elevator of this invention is greater than the respective moment arm D at the positions shown by points 2 and 3, and therefore, the actuator force required is somewhat less. However, for all intents and purposes in this art the variation in lifting actuator load or force is a minimum during the entire lifting cycle, and the actuator load is relatively constant during the entire lifting cycle as compared to the actuator load in prior art elevators wherein a moment arm such as is moment arm D herein is absent at initial lift-off and the moment arms between the respective centerlines of the actuator means and the respective scissors lift arm pivot points (said moment arms being through the pivot point and perpendicular to said centerlines) regularly increase proportionately to the lifting distance, as shown by line S, during the entire lifting cycle. Further, in the elevator of this invention, moment arm D remains almost constant, as compared to the analogous moment arms present in the elevators of the prior art elevators, as shown by the plots in FIG. 4 of the appended drawings.

With further reference to FIG. 3 curve M shows the path followed by pivot pins 50 during the upward travel of the scissors linkage and the platform, and there results a movement of said platform in the direction of arrow X, pivot pins 50 being fixed with relation to platform 32. However, rollers 30 being movable with relation to platform 32, curve N shows the path followed by rollers 30 during the upward travel of the scissors linkage and the platform.

W at IS claimed;

1. A cargo-loading elevator comprising a base, a load platform, a scissors linkage for raising the platform from a lowered to a raised position and including firstvand second frames which are pivoted together substantially midway between their ends to form said scissors linkage, each frame including a pair of spaced arms wit braces interconnecting the arms of said pair, fixed pivots mounting one end of the first frame at a first end of the base, and fixed pivots mounting the adjacent end of the second frame to the movable platform at said first end, rollers pivoted at the opposite ends of said frames, and trackways extending longitudinally of the base and platform at the opposite end of the elevator on which the rollers travel as the platform is raised and lowered, the arms in each frame having first offset sections which are offset below the general plane of the frame, the pivots connecting said frames to form the scissors linkage passing through said offset portions below said planes, one of said frames also having a second offset portion which is offset above the plane of said frame at a point between said scissors linkage pivots and the platform, .a hydraulic piston, piston rod and cylinder assembly pivotally connected at one end thereof to said second offset portion lying above said plane and at its other end to a point adjacent the base.

2. The structure defined in claim 2 wherein the frame having the second offset portion, to which one end of the hydraulic assembly is connected, is the second frame and the other end of the hydraulic assembly is connected to the base by a fixed pivot which is adjacent the first frame base pivot.

3. The structure defined in claim 1 wherein the combined distance of the pivots below and above said general planes of the frames constitutes a moment arm and the length of each frame is between seven and thirteen times the length of the moment arm.

4. The structure defined in claim 1 wherein the frames are provided with extensions below and above said general planes through which said several pivots pass.

5. The structure defined in claim I wherein the frame having the second extension, to which the hydraulic assembly is connected, is the first frame.

N 2309 l0l0l5 I I I. I. I

Claims (5)

1. A cargo-loading elevator comprising a base, a load platform, a scissors linkage for raising the platform from a lowered to a raised position and including first and second frames which are pivoted together substantially midway between their ends to form said scissors linkage, each frame including a pair of spaced arms wit braces interconnecting The arms of said pair, fixed pivots mounting one end of the first frame at a first end of the base, and fixed pivots mounting the adjacent end of the second frame to the movable platform at said first end, rollers pivoted at the opposite ends of said frames, and trackways extending longitudinally of the base and platform at the opposite end of the elevator on which the rollers travel as the platform is raised and lowered, the arms in each frame having first offset sections which are offset below the general plane of the frame, the pivots connecting said frames to form the scissors linkage passing through said offset portions below said planes, one of said frames also having a second offset portion which is offset above the plane of said frame at a point between said scissors linkage pivots and the platform, a hydraulic piston, piston rod and cylinder assembly pivotally connected at one end thereof to said second offset portion lying above said plane and at its other end to a point adjacent the base.

2. The structure defined in claim 2 wherein the frame having the second offset portion, to which one end of the hydraulic assembly is connected, is the second frame and the other end of the hydraulic assembly is connected to the base by a fixed pivot which is adjacent the first frame base pivot.

3. The structure defined in claim 1 wherein the combined distance of the pivots below and above said general planes of the frames constitutes a moment arm and the length of each frame is between seven and thirteen times the length of the moment arm.

4. The structure defined in claim 1 wherein the frames are provided with extensions below and above said general planes through which said several pivots pass.

5. The structure defined in claim 1 wherein the frame having the second extension, to which the hydraulic assembly is connected, is the first frame.

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