US3275297A

US3275297A - Hoisting truck having piston actuated parallelogram bars

Info

Publication number: US3275297A
Application number: US424682A
Authority: US
Inventors: Bloch Erich
Original assignee: AERONAUTICAL MACHINERY CORP
Current assignee: AERONAUTICAL MACHINERY CORP
Priority date: 1965-01-11
Filing date: 1965-01-11
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27
Also published as: GB1086290A

Description

E. BLOCH Sept. 27, 1966 HOISTING TRUCK HAVING PISTON AGTUATED PARALLELOGRAM BARS Filed Jan. 11, 1965 5 Sheets-Sheet 1 INVENTOR ERZCH BLOCH ATTORNEY E. BLOCH Sept. 27, 1966 HOISTING TRUCK HAVING PISTON ACTUATED PARALLELOGRAM BARS 5 Sheets-Sheet 2 Filed Jan. 11, 1965 ATTORNEY Sept. 27, 1966 E. BLOCH 3,275,297

HOISTING TRUCK HAVING PISTON ACTUATED PARALLELOGRAM BARS Filed Jan. 11, 1965 5 Sheets-Sheet 5 INVENTOR Ell 6H BLOC/Y ATTORNEY Sept. 27, 1966 E. BLOCH 3,275,297

HOISIING TRUCK HAVING PISTON ACTUATED PARALLELOGRAM BARS 5 Sheets-Sheet 4 Filed Jan. 11, 1965 iNVENTOR EPZGH BLOC/Y BY O41 ATTORNEY Sept. 27, W56 E. BLOCH 3,275,297

HOIS'IING TRUCK HAVING PISTON ACTUATED PARALLELOGRAM BARS Filed Jan. 11, 1965 5 Sheets-Sheet 5 l E;- flqnla Eda-l5 P15 54 :52 55 T i pg INVENTOR ERJCH BLOC ATTORNEY United States Patent 3,275,297 HOISTING TRUCK HAVING PISTON ACTUATED PARALLELOGRAM BARS Erich Bloch, New York, N.Y., assignor to Aeronautical Machinery Corporation, a corporation of New Jersey Filed Jan. 11, 1965, Ser. No. 424,682 9 Claims. (Cl. 254--10) The present invention relates to lifting devices having a lifting lever arm with a load supporting part movable up and down, and is an improvement over the general type of lifting device shown in my US. Patent 2,377,477 issued June 5, 1945. Although the lifting device of the present invention has a wide range of utility, it finds particular usefulness in raising the tail or wings, or other parts of an airplane, for any purpose, as for example, to change tires, make repairs or for inspection purposes.

In the aforesaid patented construction, the lifting lever arm is pivotally supported at one end to a truck frame for movement about an axis fixed in relation to the frame, and is angularly raised about its pivot support to move the other load supporting end of the lifting lever arm up and down. arm follows a circular path and this makes it necessary to utilize only a certain section of this circular movement in order that the load supporting end of the lifting lever arm in its highest position is practically on a vertical line above its starting point in its lowest position. If the lifting lever arm were raised beyond this highest position, it would move considerably back or laterally from this vertical line, and this would exert great stress to the object being lifted, especially if it should be an airplane. To avoid this condition, the lift range of the lifting device must be unduly limited.

One object of the present invention is to provide a new and improved lifting device, which has substantially greater lift range than was possible with lifting devices of the same general type in the prior art.

To carry out the objective of the present invention, instead of supporting the lifting lever arm for angular movement about an axis fixed in relation to the truck frame, so that the load supporting end swings about a circular path, the angular movement of the lifting lever arm is so modified that its load supporting end in its movement follows substantially a straight line up and down. At the same time, the power unit for the lifting lever arm is so designed and so related to said lifting lever arm as to utilize the substantially straight line movement of the load supporting end of the lifting lever arm to greatly increase the lifting range and lifting capacity of the lifting device.

Various other objects, features and advantages of the invention are apparent from the following description and from the accompanying drawings, in which FIG. 1 is a side elevation of the lifting device embodying the present invention and shown in inoperative position;

FIG. 2 is a top plan view of the lifting device and shown with parts broken away to reveal interior structure;

FIG. 3 is a rear elevation of the lifting device;

FIG. 4 is a side elevation of the lifting device shown with the lifting lever arm in load supporting fully elevated position, and with a jack tube associated therewith in upright position ready to effect additional lift through the action of said jack tube, said lifting device being shown with parts broken away to reveal interior structure;

FIG. 5 shows the lifting device in the position corresponding to that shown in FIG. 4, but shows the lifting device partly in side elevation and partly in vertical section taken along the lines 55 of FIG. 7;

FIG. 6 is a side elevation of a detail part of the lifting The load supporting end of the lifting lever.

ice

device in the region around the head end of the lifting lever arm, while said arm is reposing substantially in horizontal position;

FIG. 7 is a section of the lifting device taken substantially along the lines 77 of FIG. 4;

FIG. 8 is a detail section taken substantially along the lines 88 of FIG. 6;

FIG. 9 is a section of the tube jack taken along the lines 99 of FIG. 4;

FIG. 10 is a detail section of the ratchet mechanism for the tube jack taken along the 'lines 1010 of FIG. 9;

FIG. 11 is a detail section taken along the lines 11--11 of FIG. 4;

FIG. 12 is a detail section of guide means and stabilizer means for the lifting lever arm taken approximately along the lines 1212 of FIG. 3; and

FIGS. 13, 14, 15 and 16 are detail sections of the guide means and stabilizing means for the lifting lever arm taken on lines 13-13, 14-14, 1515 and 1 616 of FIG. 12 respectively.

Referring to the drawings, and especially to FIGS. 1-5, the lifting device of the present invention comprises a truck frame 10 having two side frame pieces 11 in the form of channels, adapted to receive partially therein two support arms 12 respectively in inoperative position and spaced by an opening 13 to receive therein while in inoperative position a lifting lever arm 14. The truck frame 10 also has a housing 15 at its rear end for the means which guide the rear end of the lifting lever arm 14, and modify the movement of the load lifting end of the lever arm.

The truck frame 10 is supported on a pair of front wheels 16 and on a pair of rear wheels 17 having their axles journalled in bearings aflixed to the frame, and a rear handle 18 removably attached to the top of the guide housing 15 and a fixed handle 19 on the front end of the truck frame, permit the lifting device to be easily handled for transportation. A pair of spring-pressed swivel caster wheels .20 near the front of the truck frame 10 supported on pads 21, raise the forward end of the lifting device when not loaded, so that the lifting device does not rest on the front wheels 16 but on the caster wheels, and this permits the lifting device to be easily steered into the desired position for load lifting operations. Under load, the forward end of the lifting device comes down for support on the front wheels 16. A pair of ground stabilizing brakes 22 on screw shafts 23, which terminate in handles 24 at their upper ends and which are threaded in bushings on the truck frame 10, serve to lock the lifting device in position against movement along the ground while under load.

The lifting lever arm 14 in inoperative position shown in FIGS. 1 and 2, nests compactly in the truck frame opening 13 between the two side frame pieces 11 as described and its forward end is designed to support the load to be raised in the manner to be described. This lifting lever arm 14 is in the form of an inverted channel to nest therein a jack tube 25, serving a purpose to be described, and has side flanges 26. Axially aligned pivot pins 27 near the rear ends of the support arms 12 pivotally connect these side flanges 26 intermediate the ends of the lifting lever arm 14 to the two support arms 12 respectively on opposite sides of the lifting lever arm 14. The other forward ends of the support arms 12 are pivotally secured to the side pieces 11 of the truck frame 10 by means of axially aligned pivot pins 28 for angular movements about axes fixed in relation to the frame.

The lifting lever arm 14 is powered into elevated position through the support arms 12 by means of two power power units 30, which are shown of the well-known telescopic ram type operated hydraulically or by air pressure. In the specific form shown, each of the fluid-power units 30 comprises a cylinder 31 having one end pivotally connected by means of a pin 32 to the channel flanges of the corresponding side pieces 11 of the truck frame and two telescopic rams 33 and 34 (FIG. 4), slidable in said cylinder, the innermost ram 34 being pivotally connected to the corresponding support arm 12 near the rear end of said arni by a wrist pin 35. The cylinder 31 has an inlet 36 connected by means of a connection (not shown) to a source of fluid power, which may be oil, water, or air, and the rear end of the inner ram 34 is in fluid communication with this cylinder inlet 36 The inner ram 34 is desirably of solid construction, or at least has a solid rear wall against which the power fluid acts, and is provided at this rear end with an annular flange slidable with a snug slide fit along the inner walls of the outer hollow ram 33 into which the inner ram 34 telescopes. The forward end of the inner ram 34 has threaded thereinto beyond the forward end of the outer ram 33, the threaded shank of a clevis 37 embracing with a snug rotative fit the corresponding wrist pin 35 on the corresponding support arm 12, and this inner ram 34 passes with a snug slide sealing fit through a hole in a cap 38 closing the forward end of the outer ram 33. The outer ram 33 also has a rear annular flange slidable with a snug slide fit along the inner walls of the cylinder 31 and passes with a snug slide sealing fit through a hole in a cap 40 closing the forward end of the cylinder 31.

In inoperative position of each power ram unit 30, the two

rams

33 and 34 are fully telescopically withdrawn into the cylinder 31 and the corresponding support arm 12 is tilted slightly upwardly and rearwardly from its fixed pivot support 28 and partially nested in the corresponding channel side frame pieces 11, as shown in FIG. 1. When the inlet 36 to the cylinder is opened to the source of fluid power, the inner ram 34 moves outwardly, first causing the corresponding support arm 12 to swing counterclockwise (FIG. 1) about the axis of its pivot support 28, until this inner ram is fully extended and its rear flange is shouldered against the cap 38 on the forward end of the outer ram 33. This manner to cause the forward load bearing end of the lifting lever arm 14 to follow a substantially vertical straight path in its load lifting movements, the rear end of the lifting lever arm is made to follow a substantially horizontal translational path. In this way, the effective lifting range of the lifting device is increased, and stresses on the load being lifted by lateral movements of the load caused by circular movements of the forward load bearing end of the lifting lever arm 14 are obviated.

F-or horizontally guiding the rear end of the lifting lever arm 14 for the purpose described and to hold the rear end of the lifting lever arm against upward movement about the axes of its pivot pins 27 due causes the outer ram 33 to be extended under fluid power,

causing thereby the corresponding support arm 12 to turn the closure cap 40 of the cylinder 31, thereby causing the power ram units 30 to reach extended stop positions.

During the angular movements of the support arms 12 about the aligned axes of the pivot pin 28, the power ram units 30 are permitted to swing angularly about the aligned axes of their pivot pins 32 to accommodate for the angular movements of the support arms 12 described.

The support arms 12 are channel-shaped as described, each having side flanges or Webs 45 and 46, and in inoperative position shown in FIGS. 1 and 2, the rear ends of these support arms house and shield the upper parts of the power ram units 30. The inside flanges 45 of these support arms 12 are pivotally secured to the flanges 26 of the lifting leverarm 14 by means of the axially aligned pivot pins 27, so that as the support arms 12 swing-about their fixed axes at the pivot pins 28, the lifting lever arm 14 in the region of the pivot pin 27 will swing about the fixed aligned axes of these pivot pins 28.

The path of the forward load bearing end of the lever arm 14 during this angular movement of this region of the lever arm about the fixed axes of the pivot pins 28, will depend on the pattern of angular movement of the lever arm about the axes of the pivot pins 27, and this pattern is controlled in accordance with the present invention, to cause the forward load bearing end of the lever arm to follow a vertical path, or at least an arcuate path .of such large radius as to be substantially vertical.

In order to control the angular movement of the lifting .lever arm 14 about the axes of the pivot pins 27 in a to the downward pressure of the load being lifted on the forward load supporting end of the lifting lever arm, guiding and holding means 49 are provided in conjunction with the frame housing 15 atthe rear of the truck frame 10. For that purpose, housing 15 has a cap 50 to which two upper guide strips 51 (FIGS. 3 and 12-16) are secured along its sides by welding as shown or by studs and has side walls 52 to which two lower guide strips 54, located directly underneath and spaced fnom the guide strips 51, are secured by welding as shown or by studs. Secured by welding as shown or by studs to the underside of the cap 50 are two rails 57 located side by side close to each other midway between the upper guide strips 51.

The rear end of the lifting lever arm 14 has rigid therewith along its sides, limbs or extensions terminating in respective bushings 61 and a middle extension terminating in a bushing 63, and a roller axle 64 supported in said

bushings

61 and 63, carries two rollers 65 intermediate its ends, supported on anti-friction bearings for free rotation, and riding on the rails 57 respectively and two rollers 66 at the ends of the axle supported on antifriction bearings for free rotation and riding along the upper guide strips 51. The rollers 65 are located between the outside bushings 61 and on opposite sides of the middle bushing 63.

With the construction so far described, as the support arms 12 move in unison counterclockwise (FIG. 1) about the fixed axes of the pivot pins 28 through the operation of the power ram units 30, the regions of the lifting lever arm 14 at the pivot pins 27 move angularly about said fixed axes, while the rear end of said lever arm 14 moves forwardly and is guided in a substantially horizontal direction by the riding engagements of the

rollers

65 and 66 carried by the rear end 'of said lifting lever arm with the rails 57 and guide strips 51. This causes the forward load supporting end of the lifting lever arm 14 to move upwardly in a substantially vertical straight line direction.

The forward load supporting end of the lifting lever arm 14 is designed to support the load to be raised. For that purpose, there is pivotally secured to the forward end of the lifting lever arm 14 in a manner to be described, a head 70 (FIGS. 1, 4, 5, 6 and 8) in the form of a collar having a hole 71 through which a lift tube 72 forming part of the tube jack 25 is adapted to pass in the lifting operation of said tube jack and into which the shank 73 of an extension adapter 74 for a jack pad 75 is adapted to fit for seating engagement on said head.

The head 70 has on diametrical opposite sides thereof, integral or otherwise rigid therewith, two bosses with respective grooves 81 :and diametrically aligned bearing holes 82. The lifting lever arm 14 at its forward end has two substantially parallel limbs 83 with respective axially aligned holes 84. These limbs 83 extend into the grooves 81 of the bosses 80 with snug rotative fits and with the

holes

82 and 84 aligned, and pivot pins 85 passing through the aligned

holes

82 and 84 and locked to the limbs 83 by set screws 86, pivotally connect the lifting lever arm 14 to the head 70.

By means of the pivotal connection between the lifting lever arm 14 and the head 70, the head 70 can be maintained with its load supporting surface horizontal while the lifting lever arm 14 is swinging about its pivotal support 27 (FIG. 4) for load lifting action. However, to stabilize the head 70 so that it is held against angular movement while the lifting lever arm 14 is swinging about its pivotal support 27 for load lifting action, there is provided a stabilizing link 90 (FIGS. 1, 2, 4, 5, 6 and 8) related to the lifting lever arm.14 and to the head 70 to form therewith a parallel motion mechanism. This stabilizing Farm 90 is in the form of a skeletonized structure comprising a pair of opposed interconnected side pieces having intermediate sections 91 nested into the lifting lever arm 14, forward end limb sections 92, extending outwardly beyond the sides of the lifting lever arm and rear end limb sections 93. The forward end limb sections 92 of the stabilizing arm 90 flank the outside of the lower ends of the bosses 80 on the head 70 and are pivotally connected thereto by axially aligned pivot pins 94 passing through said limb sections 92 and into bearing holes 95 in the bosses 80 and locked to said limb sections by means of set screws 96. In this manner, the forward ends of the lifting lever arm 14 and of the stabilizing arm 90 are linked together through the head 70 forming a connecting link therebetween.

The rear ends of the lifting lever arm 14 and the stabilizing arm 90 are also linked together to complete the parallel motion mechanism described. For that purpose, two spaced idler links 100 (FIGS. 3, and 12-16) in the form of triangular plates are supported at one corner on the roller axle 64 for limited rotation about the axis of said axle and at another corner, these links carry respective axially aligned stub shafts 101 at the outer ends of which are supported on anti-friction bearings, rollers 102, similar to the rollers 66, riding between guide strips 51 and 54. The third corners of the idler links 100 are connected together by an axle bolt 103.

The idler links 100 are supported in the manner de scribed for angular movement in unison about the axis of the supporting roller axle 64, but this angular movement is restricted in one direction by the engagement of the rollers 102 with the upper guide strips 51 and in the other direction by the engagement of the rollers 102 with the lower guide strips 54. There is very little play of the rollers 102 between the guide strips 51 and 54, but just enough to permit these rollers to ride along the upper strips 51 or the lower strips 54, with free rotation, as the rear end of the lifting lever arm 14 is moved horizontally along the guiding means.

As the lifting lever arm 14 is moved angularly about the axis of its pivotal supports 27 (FIG. 2) for lifting and raising operations, the load on the head 70 tends to tilt this head about the axes of the pivot pins 85 (FIGS. 6 and 8) pivotally connecting the forward end of this arm to said head, and the tilting stresses on this head are transmitted endwise to the stabilizer arm 90. These stresses on the stabilizer arm 90 are transmitted by the arm at its end to spaced idler links 104 (FIGS. 3, 12-16) in the form of substantially triangular plates supported at one corner on the stub shafts 101 respectively. These idler links 104 are connected at another corner to the idler links 100 at a corner of the latter links by supporting these corners of the idler links 104 on the axle bolt 103. The third corners of the idler links 104 are connected together by a bolt 106 serving as an axle for the rear end limb sections 93 of the stabilizer arm 90.

The idler links 100 have respective hubs 110 snugly embracing the axle bolt 103 and the idler links 104 have respective hubs 111 snugly embracing the stub shafts 101. The

idler links

100 and 104 are arranged in opposed pairs, each pair consisting of a link 100 and a link 104 ararnged so that their

hubs

110 and 111 extend as spacers toward each other, with the hub of each link of each pair engaging the other link. A sleeve 112 on the axle bolt 103 between the idler links 104 assists in holding these idler links against axial displacements. The two idler links and 104 of each pair of links are thereby, in effect, connected together for pivotal movement in unison about the axis of the roller axle 64, with the hubs and 111 at two corners of the pair of links separating said links and with the links of each pair relatively displaced out of alignment, so that the corners of the idler links 104 to which the rear ends of the stabilizer 90 are pivotally joined, project outwardly from one side of the idler links 100, as shown in FIG. 12.

The rear end limb sections 93 of the stabilizer arm 90 have holes through which the axle bolt 106 passes with a snug rotative fit, permitting the stabilizing arm to move angularly about the axis of said bolt relative to the

idler links

100 and 104. These rear end limb sections 93 are held on the axle bolt 106 between the idler links 104 and a sleeve 113 on said bolt extends between said limb sections.

With the construction described, the rear ends of the lifting lever arm 14 and of the stabilizer arm 90 are interconnected by the

idler links

100 and 104, and as the endwise stresses are transmitted to the stabilizer arm by the load lifting and load lowering movements of the lifting lever arm 14 in the manner described, these stresses transmitted to said idler links, cause said idler links to swing in unison about the axis of the roller axle 64, thereby causing the rollers 102 to move upwardly into riding engagement with the upper guide strips 51 or into riding engagement with the lower guide strips 54, according to the direction of the longitudinal forces on the stabilizer arm 90.

The distance between the axis of the roller axle 64 and the axis of the axle bolt 106 at the rear ends of the lifting lever arm 14 and the stabilizer 90 is equal to the distance between the aligned axes of the pivot pins 85 and the aligned axes of the pivot pins 94 at the forward ends of said lifting lever arm and said stabilizer arm 90, and the plane passing through the axis of the roller axle 64 and the axis of the axle bolt 106 is parallel to the plane passing through the axes of the pivot pins 85 and the axes of the pivot pins 94, and these planes remain at a constant angle with respect to a vertical plane during the full range of movement of the lifting lever arm.

The lifting lever arm 14 is operated in the manner made apparent to cause its forward load supporting end to move substantially vertically to the limit permitted by the power ram units 30, when the power units have reached a stopped position. Thereafter, the load can be transferred to the tube jack 25, which is more positive in its supporting operation. In inoperative position of the lifting device, the tube jack 25 extends in a low position along the truck frame 10 nested in the lifting lever arm 14, as shown in FIGS. 1 and 2, and is pivotally supported at its forward end to the forward end of the lifting lever arm 14 through the head 70 of the lifting lever arm. For that purpose, the tube jack 25 has an outer tubular casing 115 (FIGS. 6 and 8) and the bosses 80 on said head 70 project downwardly sufliciently to flank the upper end of the casing and the upper end of the casing 115 is pivotally connected to the flanking ends of the bosses by means of axially aligned pivot pins 116 held in position against accidental withdrawal by set screws 117.

In inoperative position of the lifting device, the rear end of the tube jack 25 is removably secured to the lifting lever arm 14 by means of a chain 118 (FIG. 5) releasab-ly connected to the casing 115 of the tube jack near its rear end. By means of this attachment, as the lifting lever arm 14 is operated through the power rarn units 30 into load raising position, the tube jack 25 moves with the lifting lever arm, until this lifting lever arm reaches the limit reached by the power ram units 30, as shown in FIGS. 3 and 5. In this limting position of the lifting lever arm 14, the chain 118 is released from the tube jack 25, causing said tube jack to gravitationally swing clockwise (FIG. about the aligned axes of the pivot pins 116, until the tube jack reaches the vertical position shown in FIGS. 4 and 5. In order to removably lock the lower end of the tube jack 25 against movement while in this vertical position, there is secured to the truck frame near its forward end, by means of brackets 120, a pair of similar superposed lock plates 121 (FIGS. 5 and 11), each having a pair of recesses 122, and the lower end of the tube jack has two pins 123, which fall into these recesses respectively when the tube jack swings into vertical position shown in FIGS. 3 and 5. For releasably holding these pins 123 in the recesses 122 of the lock plate 121, a locking rod 124 chained to the truck frame 10 is passed through vholes in plates 125 forming parts of the side pieces 11 of the truck frame, so that said locking rod block-s withdrawal of the locking pins 123 from the plate recesses 122.

The tube jack 25 comprises the tubular casing 115 as described, the lower end of which is enlarged to form a gear housing 126 (FIGS. 9 and 10). At the bottom of the gear housing 126 is journalled a shaft 127 carrying a bevel gear 128 and also a vertical power screw 129 threaded into the lift tube 72 of the tube jack 25. The lift tube 72 has a slot 131 along its length into which fits a key 132 secured to the casing 115 of the tube jack 25 to lock the lift tube against turning, while permitting the lift tube to move vertically in response to the rotation of the power screw 129. r

A ratchet device for turning the power screw 129, comprises ratchet housing 135, which is supported for rotation about a shaft 136 journalled in a bearing 137 on the side of the gear housing 126 and which carries a pawl 138 engaging a ratchet wheel 140 secured to said shaft 136. The ratchet housing 135 has a socket 141 for a removable level handle by which the housing 135 can be turned to turn the ratchet wheel 140. Also secured to the shaft 136 is a bevel gear 142 meshing with the bevel gear 128 by which the power screw 129 can be turned.

The upper end of the lift tube 72 of the tube jack 25 has fitted therein a pilot 143 secured to the lift tube by a screw 144 and having a conical head. The adapter 74 has an annular flange v14 5 for seating on the upper end of the head 70 of the lifting lever arm 14 and has its shank '7'3 fitting almost snugly inside the head 70 and having a conical recess 147 for confiormably receiving the conical head of the pilot 143 of the jack tube 25, when the lift tube 72 has been raised sufiiciently to cause this pilot to fit into this adapter shank The adapter 74 can have the jack pad 75 integral therewith or permanently secured thereto or this pad 75 may be removable from the adapter, and for that purpose may consist merely of a head with a shank or stem fitting snugly and removably into a hole in the adapter.

In the inoperative positions of the jack tube 25, shown in FIGS. 1 and 6, its lift tube 72 is sufficiently withdrawn int-o the casing 115 of the tube jack, so that the pilot 146 does not interfere with the head 70 of the lifting lever arm 14, as this tube jack swings relative to the head 70 about the aligned axes of the pivot pins 116 from a substantially horizontal position to a vertical position shown in FIG. 9. When the tube jack 25 has reached this vertical position shown in FIG. 9, after the lifting lever arm 14- has reached the limit of its load lifting operation, the tube jack 25 is operated through its

ratchet mechanism

135, 138 and 140, decribed, until the pilot 143 engages the adapter 74, whereupon the load is transferred from the lifting lever arm 14 to the tube jack. Continued operation of the ratchet mechanism of the tube jack 25 will raise the load the additional amount to the limit of the tube jack operation, while the lifting lever arm 14 with its head 70 remains in the limiting positions shown in FIGS. 4 and 5 but free from the load.

The jack pad 75 is adapted to fit a jack point (not shown) secured to the part of the load, as for example, the underside of the tail or wing of an aircraft to be 8 lifted. This jack pad 75 operates for that purpose, not only during the full operation of the lifting lever arm 14 but also during the additional full operation of the tube jack 25, without changeovers in the jack points of support of the aircraft.

While the invention has been described with particular reference to a specific embodiment, \it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted solely by the scope of the appended claims.

What is claimed is:

1. A lifting device comprising a single lifting lever arm having spaced interconnected side walls defining therebetween a hollow having an end for supporting and raising a load, means for imparting to said lever arm a movement in a direction to cause said load supporting and raising end to move in a vertical direction, a tube jack extending along said lever arm and nested in said hollow in inoperative lowermost position of said lifting device, and means for moving said tube jack from said inoperative posit-ion towards upright position as said end of the lever arm is raised and for lining up said tube jack in upright position underneath said end of the lever arm as said end of the lever arm reaches the upper part of its upward movement, said tube jack being adapted in upright position to pick up the load from said end of the lever arm in the uppermost position of said end of the lever arm and to lift it an additional amount permitted by the range of opera-tion of said tube jack.

2. A lifting device comprising a lifting lever arm having an end for support-ing and raising a load, means for supporting and guiding said lever arm for combined rotational and translational movements and for actuating said lever arm through said movements in a manner to cause said load supporting end of the lever arm to move up and down while the other end of said lever arm is urged upwardly by the load on said load supporting end of the lever but is restricted to movement in a straight direction, said lever supporting and guiding means com-.

prising rail means extending along said direction, an axle supported on said other end of the lever arm, and roller means carried by said other end of the lever arm in riding engagement with said rail means, said rail means being located to resist said upward movement of said other end of the lever arm while permitting said other end of the lever arm to move along said direction, a head pivotally secured to said load supporting end of the lever arm for transmitting the pressure from the load to said load supporting end of the lever arm, a stabilizing arm for said head extending along said lever arm, and connecting means between said lever arm and said stabilizer arm forming with said arm a parallel motion mechanism comprising said head to which one end of said stabilizer arm is pivotally connected, idler link means pivotally supported on said axle, the other end of said stabilizer arm being pivotally secured to said idler link means, guide strip means extending along said directions, and roller means on said idler link means in riding engagement with said guide strip means.

3. A lifting device comprising a lifting lever arm having an end for supporting and raising a load, a pair of support arms flanking said lever arm and each having a pair of spaced side webs facing each other, said support arms having respective regions pivotally supported at axially aligned axes which are fixed during the operation of the lifting device and having also respective regions pivotally secured to parts of said lifting lever arm at axially aligned movable axes spaced from said end of the lever arm, means for moving said support arms in unison angularly about said fixed axes, to cause said parts of the lever arm to move an gularly about said fixed axes, and comprising a pair of fluid power ram units having respective power cylinders pivotally connected at one end for angular movements about aligned axes fixed during operation of the lifting device and having respective rams operable in and out from the other ends of said cylinders and pivotally connected to said support arms respectively, substantial longitudinal parts of said cylinders near said other ends being nested in said support rams operable in and out from the other ends of said support arms, each cylinder in said initial position being located at said other end between the webs of the corresponding support arm, and means for controlling the movements of said lever arm about said axially movable axes to cause said end of the lever arm to move up and down.

4. A lifting device as described in claim 3, wherein each of said support arms is in the form of an inverted channel and each of said pair of spaced webs constitutes the side webs of the channel.

5. A lifting device as described in claim 3, comprising a truck frame, said support arms being pivotally secured to said truck frame at said first mentioned fixed axes, said cylinders 'being pivotally secured to said truck frame for angular movements about the other fixed axes, said lifting lever arm in inoperative initial position being nested between said support arms close to said truck frame and said support arms lying close to said truck frame in inoperative initial position of said support arms.

6. A lifting device comprising a lifting lever arm having an end for supporting and raising a load, a pair of support arms on the outside of and flanking said lever arm, and having respective regions pivotally supported at axially aligned axes fixed during the operation of the lifting device, and having also respective regions pivotally secured to said lever arm on a common axis movable with said support arms about said fixed axes and located intermediate the ends of said lever arm, means for moving said support arms in unison angularly about said fixed axes, and comprising a pair of fluid power ram units on the opposite outer sides of said lever arm having power actuable means connected to said support arms for moving said support arms about said fixed axes, and means for controlling and guiding the movements of a region of said lever arm near the other end thereof in a direction to cause said load supporting end to move up and down substantially vertically while said support arms are moved about said fixed axes, and comprising an axle carried by said lever arm near the con-' trolled and guided region of said lever arm and having its axis extending transverse to the longitudinal direction of the lever arm, roller means carried by said axle substantially midway between the sides of said lever arm, and rail means for said roller means fixed during the operation of the lifting device.

7. A lifting device comprising a lifting lever arm having an end for supporting and raising a load, a pair of support arms on the outside of and flanking said lever arm, and having respective regions pivotally supported at axilly aligned axes fixed during the operation of the lifting device and having also respective regions pivotally secured to said lifting lever arm on a common axis movable with said support arms about said fixed axes and located intermediate the ends of said lever arm, means for moving said support arms in unison angularly about said fixed axes, and comprising a pair of fluid power ram units on the outside of said lever arm having re- Spective power cylinders pivotally connected at one end for angular movements about aligned axes fixed during operation of the lifting device and having respective rams operable in and out of said cylinders respectively and pivotally connected to said support arms respectively, and means for controlling and guiding the movements of a region of said lever arm near the other end thereof in a direction to cause said load supporting end of the lever arm to move up and down while said support arms are moved about said first-mentioned fixed axes.

8. A lifting device comprising a single lifting lever arm having an end for supporting and raising a load, a

pair of support arms on the outside of and flanking said lever arm, and having respective regions pivotally supported at axially aligned axes fixed during the operation of the lifting device, and having also respective regions pivotally secured to said lifting lever arm on a common axis movable with said support arms about said fixed axes and located intermediate the ends of said lever arm, means for moving said support arms in unison angularly about said fixed axes, and comprising a pair of fluid power ram units on the outside of said lever arm having power actuable means connected to said support arms for moving said support arms about said fixed axes, means for controlling and guiding the movements of a region of said lever arm near the other end thereof in a direction to cause said load supporting end to move up and down vertically while said support arms are moved about said fixed axes, said l'ever arm having spaced interconnected opposite side walls defining therebetween a hollow, a tube jack extending along said lever arm and nested in said hollow in inoperative lowermost position of said lifting device, and means for moving said tube jack from said inoperative position towards upright position as said load supporting end of the lever arm is raised and for lining up said tube jack in upright position underneath said load supporting end of the lever arm as said load supporting end of the lever arm reaches the upper part of its upward movement, said tube jack being adapted in upright position to pick up the load from said load suporting end of the lever arm in the upermost position of said load supporting end of the lever arm to lift said load supporting end of the lever arm an additional amount permitted by the range of operation of said tube jack.

9. A lifting device comprising a truck frame, wheels supporting said frame for portability, a lifting lever arm having an end for supporting and raising a load, and having its major length from said end extending substantially horizontal along said frame in inoperative lowermost position of said lever arm, a pair of parallel support arms on the outside of and flanking said lever arm, pivoted near one end to said frame along a common axis fixed in relation to said frame and extending transversely to said lever arm, said support arms being pivoted near their other ends to said lever arm along a common axis parallel to said fixed axis and movable with said support arms about said fixed axis, said support arms in said inoperative position of the lever arm extending at an inclined direction with respect to the horizontal, means for controlling and guiding the movements of the other end of said lever arm in a direction to cause said load supporting end to move up and down while said support arms are moved about said fixed axis, and means for moving said support arms about said fixed axis comprising a pair of fluid power ram units on the outer opposite sides of said lever arm, having respective parallel power cylinders pivotally connected at one end to said frame for angular movements about aligned axes fixed in relation to said frame, and having respective rams ope-rable in and out of said cylinders respectively, said rams being pivotally connected to said support arms respectively near said other ends of said support arms, said cylinders and rams in inoperative position of said lever arm extending substantially at right angles to said support arms.

References Cited by the Examiner UNITED STATES PATENTS 2,099,903 11/1937 Nilson 254-9 2,377,477 6/1945 Bloch 254-10 2,476,380 7/1949 Manke 254-9 X 2,766,007 10/ 1956 Krilanovich 254-l24 WILLIAM FELDMAN, Primary Examiner.

MILTON S. MEHR, Examiner.

Claims

1. A LIFTING DEVICE COMPRISING A SINGLE LIFTING LEVER ARM HAVING SPACED INTERCONNECTED SIDE WALLS DEFINING THEREBETWEEN A HOLLOW HAVING AN END FOR SUPPORTING AND RAISING A LOAD, MEANS FOR IMPARTING TO SAID LEVER ARM A MOVEMENT IN A DIRECTION TO CASUSE SAID LOAD SUPPORTING AND RAISING END TO MOVE IN A VERTICAL DIRECTION, A TUBE JACK EXTENDING ALONG SAID LEVER ARM AND NESTED IN SAID HOLLOW IN INOPERATIVE LOWERMOST POSITION OF SAID LIFTING DEVICE, AND MEANS FOR MOVING SAID TUBE JACK FROM SAID INOPERATIVE POSITION TOWARDS UPRIGHT POSITION AS END OF THE LEVER ARM IS RAISED AND FOR LINING UP SAID TUBE JACK IN UPRIGHT POSITION UNDERNEATH SAID END OF THE LEVER ARM AS SAID END OF THE LEVER ARM REACHES THE UPPER PART OF ITS UPWARD MOVEMENT, SAID TUBE JACK BEING ADAPTED IN UPRIGHT POSITION TO PICK UP THE LOAD FROM SAID END OF THE LEVER ARM IN THE UPPERMOST POSITION OF SAID END OF THE LEVER ARM AND TO LIFT IT AN ADDITIONAL AMOUNT PERMITTED BY THE RANGE OF OPERATION OF SAID TUBE JACK.