US2868331A - Lifting appliance - Google Patents

Description

Jan. 13, 1959 J. VILLARS LIFTING APPLIANCE 3 Sheets-Sheet 1 Filed July 12, 1955 Jan. 13, 1959 J. VILLARS LIFTING APPLIANCE 3 Sheets-Sheet 2 Filed July 12, 1955 JUL/O 1441 9/95 3 4% 7 CZZ- W/ Jan. 13, 1959 J. VILLARS LIFTING APPLIANCE 3 Sheets-Sheet 3 Filed July 12, 1955 of appliance presents .several drawbacks.

goes down.

,descending, of the platform .duringthe lifting of said platform.

,r s truction of .the ,pqsition.

2 Claims. (Cl. 187-17) Lifting appliances are known for instance to render easier the loading of packages on lorries. This .kind of appliance comprises generally a motoractuating a platform carried by a movable frame. Said frame is guided vertically by means of guiding members fastened on the one hand on the sides of said frame and on the other hand on the walls of a pit entirely closed said platform when this platform is in its lower position. Said kind Particularly the cost is relatively high as the driving motor of the platform must be housed in an excavation especially made for it. Further, the Walls of the pit must be very solid in order to obviate any deformation Besides, this kind of appliance comprises generally a masssuspended by a flexible member connected niemanner that said mass will be lifted when the platforrn When the platform goes up, said rnass lightens the load on the driving motor. .However, generally the weight of said mass does not exceed the weight of -the movable frame of the platform, that is to say. that this weightis limited to the counterbalancing. of said platf rm,.in order to :obv iateth c nsider b e osts o am s -of. s ve lton The present invention has for g n object a lifting appliance comprising a platform carried by a movable frame actuated by,a,motor,and which .is/ characterized by the fact that itcomprises an auxiliary motor which constitutes an accumulator of energy storingenergy during the Theannexed drawing shows schematically and by way tofsexampletwo forms of constructionof the hlifting. ap-

pliance object of the invention.

,-Fig. lQis, a perspective view of the first form, ofconappliance, the platfor nmeingimitsdpwer Fig. 2 is a perspective view, the platform being in its lifted position, certain parts being cut away for clarity.

Fig. 3 is a cross section.

Fig. 3a is a fragmentary horizontal sectional view.

Fig. 4 is a view of a detail.

Figs. 5 and 6 are partial side and plan views of a modified form of construction of the auxiliary motor.

According to Figs. 1 to 4 of the attached drawingthe appliance comprises a platform 1 carried by a movable frame 2 having the general shape of a cage. The four side faces of said frame are covered with sides 3. The movable frame 2 is positionable within a pit 4 and is carried by means of four flexible carrying members 5. Said members 5 are constituted by cables, one extremity of each of which is fastened to a central winding drum 6, whilst the other extremity of each cable is fastened to the lower extremity of four uprights of the movable frame. Said carrying members pass over sheaves 8 rotating free on axes 9 rigidly fastened 0n the upper exof the guiding members of the movable framecarrying the platform.

and reta sa {e United States Pateht Ofiice Patent 13 1 59 tremities of four posts 10 fastened on the bottom 11 of the pit and located in the four corners of said pit 4.

The drum 6 is driven by a vertical driving shaft 12 connected by a reducing gear, housed in a casing 13, to the shaft of an electric motor 14. Said shaft 12 coniprises a prolongation 15 which constitutes the shaft or an auxiliary motor .16. Said motor 16 comprises springs wound up on themselves and one of the extremities of each of which is fastened to the shaft 15 whilst their other extremities stay against central columns 17 fastened on the bottom of the pit and carrying the casing 13 of the reducing gear. Distance pieces 18 connect rigidly the upper extremity of each post 10 to the casing 13 andto the columns 17. Said distance pieces constitute withthe posts and the columns an internal fixed frame.

When the platform is in its upper position (Fig. 2) its top is located for instance at the level of the deck of truck (Fig. 2).

When the electric motor 14 is energized by lowering of a control member M of a control casing C, the user causesthe lowering of the platform. The movable frame enters inside the pit. During said lowering stroke of the platform, the electric motor 14 winds up the springs and consequently winds up the auxiliary motor. When the top of the platform reaches the level of the ground, an abutment 19 carried by themovable frame actuates the control member 20 of an end stroke circuit breaker 21 circuit breaker 24.

The tests efi ectuated, have shown i that the auxiliary motor 16 causesa large reduction in the power of the electric motor 14 which isnoimally necessary to raise a given load, corresponding to the load for which the platform is calculated, to a given height in a given time. Said auxiliarymotor, wound up by the main motor and partly bythe load carried by the platform during the lowering of said platform, constitutes in fact an accumulator of energy. The energy accumulated by this auxiliary motor is used to lift a part of carry. 1

The mechanical connection between the shaft of the motor 14- and the winding drums 6, comprises a worm 26 meshing with a worm wheel 25. The pitch bf saidworm is chosen in such a manner. as to realise an irreversible transmission, that is to say that the worm wheel subjected by the intermediary of the cables, to the action of the weight of the platform and of the load carried by said platform, may not in any case cause a rotation of said worm.

An advantage of the described appliance is that the shaftlS of the auxiliary motor carries the multiple winding drum 6. It follows that the members of the reducing gear 13 do not carry a great part of the load carried by the platform. Consequently, the wear of the members of the reducing gear is far less than in the known appliances and their life is increased.

The horizontality of the platform is ensured by the carrying cables, even if the load is located unsymmetrically on the platform. Each post 10 carries further a guiding member 27 cooperating with guides constituted by the uprights forming the corners of the frame.

From the foregoing it results that the pit necessary for the housing of the platform and of its movable frame,

the load which the piatform may built and made 1n order to allow the fastening of such guiding members. Said walls may not be absolutely vertical nor absolutely plane, without hindering thefgood working of the appliance. Besides, the total volu'm'efdf the pit necessary to house the described appliance is approximately equal tothe volume of the movable frame of the platform. On the other hand, in the known appliances, the volume of the pit is far greater (two to three times) than the volume'of the movable frame of the platform, that is to say than the volume which must be moved. 1

The energy accumulator constituted here by a spiral spring motor mechanically connected to the winding drum, may be substituted by any other kind of spring motor, such as a twisting spring for instance. The four carrying cables may be substituted by a carrying and pulling cable attached on the one hand to the lower part of an upright and on the other hand to the winding drum, and by three funicular cables of a constant length. One of the extremities of each of said three cables may be attached to the foot of one of the columns and the other extremity ofeach of the funicular cable, may be fastened to the extremity of one of the three other uprights, after having passed over a rotatable guide carried by the corresponding column. Such a disposition of pulling carrying cables and of funicular carrying cables, is already known and used for instance in lifting appliances for touring cars and described for instance in the U. S. Patent No. 2,640,562.

Figs. 5 and 6 show partially a modified form of construction of an appliance according to the invention. The auxiliary motor 16 comprises a cylinder 28 in which slides a piston 29. Said piston is mechanically connected, by means of a toothed rack 30 and a pinion 31, to the shaft 15. A duct 32 connects said cylinder to a bottle partially filled with liquid.

When the platform goes down, the piston penetrates inside the cylinder and compresses the gas contained in the upper part of said bottle 33. Said gas, perfectly elastic, restores the stored energy during the next actuating upwards displacement of the platform.

Two forms of execution of an appliance object of the invention have been described here by way of examples, :but it goes without saying that several variants may be realised, adapted to the several requirements prescribed in each particular case.

From the foregoing one may easily see that the appli ance object of the invention is of a cost which is much cheaper than the cost of an appliance of a known kind.

Besides, the consummation of electric energy and thus the power of the motor which must be foreseen, is much less than in the known appliances, for the main electric motor is of a power approximately equal to half of the power which would be necessary, in the absence of an auxiliary motor, in order to raise a given load to a given height in a given time. This particular point represents also a great advantage of the described appliance.

I claim:

1. In a lifting appliance, a platform having frame means depending therefrom, said platform and frame means being adapted to be raised from and lowered into a pit, sheaves positioned in the upper part of said pit adjacent said frame means, motive means, transmission means drivingly connected with said motive means, means supporting said motive means and said transmission means in said pit, said transmission means having a central vertical output shaft having a drum thereon, cables connected to said drum extending over said sheaves and attached to the lower ends of said frame means, and an energy accumulator in said pit, a'downward prolongation of said output shaft, said accumulator being operatively connected to said prolongation of said output shaft of said transmission means; whereby said motion means, transmission means, support means, drum, andenergy accumulator have a combined vertical height no greater than the height of said frame means.

2. In a lifting appliance, a platform having frame means depending therefrom, said platform and frame means being adapted to be raised from and lowered into a pit, sheaves positioned in the upper part of said pit adjacent said frame means, motive means, transmission means drivingly connected with said motive means, meansv supporting said motive means and said transmission means in said pit, said transmission means having an out-- put shaft having a drumthereon, cables connected to said drum extending over said sheaves and attached to the lower ends of said frame means and an energy accumulator in said pit, a downward prolongation of said output shaft of said transmission means, said energy accumulator comprising spring means having one end thereof attached to said downward prolongation of said output shaft and the other end anchored to a fixed object, whereby said motive means, transmission means, support means, drum and spring means of said-energy accumulator have a combined vertical height no greater than the height of said frame means.

References Cited in the file of this patent UNITED STATES PATENTS 269,994 Bailey Ian. 2, 1883 544,780 Winters Aug. 20, 1895 968,501 Turner Aug. 23, 1910 1,710,552 Rood Apr. 23, 1929 1,849,348 Davis Mar. 15, 1932 2,250,965 Pritz July 29, 1941 2,269,786 Rose Jan. 13, 1942 2,517,318 Jeffers Aug. 1, 1950

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