US3823915A

US3823915A - Elevator table

Info

Publication number: US3823915A
Application number: US00319770A
Authority: US
Inventors: S Koehler
Original assignee: Trepel AG
Current assignee: Trepel AG
Priority date: 1972-02-24
Filing date: 1972-12-29
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16
Also published as: SE377322B; NL7214670A; NO137540C; DE2208777C3; ES408742A1; DE2208777A1; DE2208777B2; NO137540B; BE791776A; IT972219B

Abstract

An upper and a parallel lower platform are connected by at least two transversely spaced lever units each having two crossed levers which are pivoted at their point of intersection and whose respective upper and lower ends are provided with rollers guided in guides of the upper and lower platform, respectively. The upper and/or the lower ends of the crossed levers of each unit have associated therewith at least one additional lever one end of which is pivoted to the respective platform intermediate the ends of the levers associated therewith, whereas the other end is pivoted to one of the two levers of the unit intermediate the point of intersection of the levers and the end of the lever which is connected with the respective platform. More of the additional levers can also be provided.

Description

1111 3,823,915 1451 July 16, 1974 I ELEVATOR TABLE Siegfried Koehler, Wiesbaden, Germany [75] Inventor:

[73] Assignee: Trepel AG., Wiesbaden, Germany [22] Filed: Dec. 29, 1972 [21] Appl. No.: 319,770

[30] 9 Foreign Application Priority Data Feb. 24, 1972 Germany 2208777 521 US. Cl. '254/122 [51] Int. Cl B661 3/22 [58] Field of Search 254/122, 124; 187/18 [56] References Cited UNITED STATES PATENTS 3,112,676 12/1963 Boulsover 254/122 3,623,707 11/1971 Klopp 254/122 FOREIGN PATENTS OR APPLICATIONS 1,080,750 4/1960 Germany 254/122 428,312 12/1947 Italy 254/124 Primary Examiner-A1 Lawrence Smith Assistant Examiner-Robert C. Watson Attorney, Agent, or FirmMichael S. Striker 5 7] ABSTRACT An upper and a parallel lower platform are connected by at least two transversely spaced lever units each having two crossed levers which are pivoted at their point of intersection and whose respective upper and lower ends are provided with rollers guided in guides of the upper and lower platform, respectively. The upper and/or the lower ends of the crossed levers of each unit have associated therewith at least one additional lever one end of which is pivoted to the respective platform intermediate the endsof the levers associated therewith, whereas the other end is pivoted to one of the two levers of the unit intermediate the point of intersection of the levers and the end of the lever which is connected with the respective platform. More of the additional levers can also be provided.

8 Claims, 1 Drawing Figure 1 ELEVATOR TABLE BACKGROUND OF THE INVENTION The present invention relates to a device for raising and loweringloads, and more particularly to an elevator table.

Such tables, operating on the scissors or pantograph principle, are already known. They use an upper and a lower platform between which there are disposed two or more units each having two crossed levers. Where the levers intersect one another they are pivoted together. The lower ends of the levers are connected with the lower platform for pivoting movement about fixed pivots. The upper ends of the levers are provided with rollers which can roll in guides provided on the upper platform. It is also known to reverse the relationship so that the rollers are associated with the lower platform and the fixed pivots are associated with the upper platform.

In these prior-art constructions the center point between the four ends of the two crossed levers of each unit, that is the point of intersection between these levers, will shift in the direction towards that platform with which the lever ends are connected at the fixed pivots, as the upper platform is being raised and will move away therefrom as the upper platform is being lowered. This particular movement is of no consequence if the elevator table raises or lowers loads which are relatively light in weight, or which are not particularly long. If, however, the loads are long or are rather heavy, this movement of the point of intersection will result in an uneven distribution of the load to the lever arms of the levers, and at times this can lead to bending of the levers or even breakage thereof.

Evidently, this is undesirable and severely limits th utility of the elevator tables known from the art.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to overcome the disadvantages of the prior art.

More particularly it is an object of the present invention to provide an improved elevator table of the type under discussion, which is not possessed of the aforementioned disadvantages.

Still more particularly it is an object of the present invention to provide such an improved elevator table in which there will be no preferential shifting of the point of intersection between the crossed levers towards one or the other of the platforms.

In keeping with these objects, and with others which will become apparent hereafter, one feature of the invention resides in an elevator table which, briefly stated, comprises an upper and a parallel lower platplatforms intermediate the lever ends associated with the same, and another end portion pivoted to one of the levers of the respective unit intermediate the point of intersection and the lever ends which are associated with this one platform.

With this construction all lever ends are in rolling engagement with the respective platforms, that is none of the lever ends are connected with a platform for movement about fixed pivots. Instead, the fixed pivots, or rather the action thereof,'is replaced in the construction according to the present invention by that end of the additional lever which is connected with the respective platform. This means that when the upper platform is being raised the lever ends provided with the rollers will shift uniformly towards the center, and the point of intersection will always be in the same position relative Additional lever means comprising at least one additional lever for each unit is also provided, and this additional lever has one end portion pivoted to one of the to both platforms. As the upper platform is raised, the center of the load carried on it, and thepoint of intersection will no longer become displaced relative to one another as was the case in the prior art, and hence the uneven distribution of load to the variouslevers which has been so objectionable in the prior art is overcome.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however,

both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a somewhat diagrammatic il lustration of an exemplary embodiment of the invention. 1

DESCRIPTION OF THE PREFERRED EMBODIMENTS comprise pumps, hydraulic cylinders, hydraulic-fluid.

reservoirs and the like, all of which are entirely conventional in this particular field.

Also conventional in the illustrated embodiment is the provision of an upper platform 6 and a parallel lower platform 7. The term platform is here not restricted to any particular structural concept in this context; evidently, the lower platform 7 could be a plate, but it could also be a base of any suitable type or configuration. The platform 6 usually is plate-shaped.

The two

platforms

6 and 7 are-vertically spaced from one another and the elevator table is provided with two transversely spaced lever units 4, of which only one is illustrated, it being understood that the other one will be located behind it. It is, of course, also conceivable that only a single lever unit 4 might be utilized.

In the illustrated embodiment the lever units 4 are composed of two crossed levers 2 each having an upper lever arm 2a and a lower lever arm 2b. The levers 2 of each unit 4 are pivoted together at the pivot point 3, that is at the point of intersection of the levers 2. The

upper ends of the upper lever arms 2a'are provided with rollers 1 which are received in guide slots provided in the upper platform 6, and the lower ends of the lower lever arms 2b are similarly provided with rollers 1 which are received in guide slots of the lower platform 7.

Thus far, the construction of theillustrated elevator table is conventional except for the fact that in the prior art only one set of ends (either the upper ends or the lower ends) would be provided with the rollers 1, whereas the other ends would be connected with the respective platform for movement about fixed pivots rather than on rollers.

There is a further difference in accordance with the present invention, namely the provision of additional lever means. In the illustrated embodiment this additional lever means comprises additional levers 5. Here, the levers are provided in the form of two pair of such levers, associated with the upper and lower platforms, respectively. However, a single such lever 5 could be associated with each of the upper and lower platforms, or a single such lever 5 could be associated with one of the upper and lower platforms, or again a pair of such levers could be associated with either the platform 6 or the platform 7.

In the. illustrated embodiment, however, there are provided two pair of the levers 5, as already mentioned, each associated with one of the

platforms

6 and 7. The levers 5 associated with the lever arms 2a are pivoted to the latter midway between the point of intersection 3 and the respective roller 1, and the opposite end of each lever 5 is pivoted to the upper platform 6 via a pivot 9. The levers 5 associated with the lever arms 2b are arranged similarly, that is one end of eachlever 5 is pivoted to a respective lever arm 2b intermediate the associated roller 1 and the point of intersection 3, whereas the opposite end of the same lever-5 is pivoted withthe pivot 9 to the lower platform 7. The location of the pivots 9 is midway between the ends of the

lever arms

2a, or 2b, respectively.

In the illustrated embodiment there is provided mounting means for the pivots 9, here shown as guides 8 which so mount the pivots 9 that the same can move toward and away from the point of intersection 3 by a limited extent. Such an arrangement has the advantage that it prevents, if heavy or very heavy loads are carried on the platform 6, damage to the

levers

2 and 5 if a downward deformation of the platform 6 should result vided in form of a fluid-operated cylinder and piston I unit 10 which is connected with the platform 6 and with the pivot 9, respectively. The cylinder and piston unit is advantageously a hydraulic unit. However, other means for effecting the displacement can also be utilized. The necessary fluid lines and fluid supply means for the unit 10 have been omitted for the sake of clarlty.

If the levers 5 are connected fixedly with the platform 6 (or 7) but pivotable in the general plane of the levers 2, then the platform 6 (or 7) receives a further supporting point which means that it can be made less massive and less strong (especially if it is of large dimension) than would otherwise be necessary if there were only two supporting points (rollers 1 at the endsof the associated lever arms). lf unit 4 is provided with only a single or a pair of the levers 5, then it is advantageous if these act between the levers 2 and the platform 6, rather than between the platform 7 and the levers 2. Of course, both platforms and levers can be so provided.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types'described above.

While the invention has been illustrated and described as embodied inan elevator table, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range-of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. An elevator table, comprising an upper and a parallel lower platform; at least one lever unit intermediate said platforms and comprising two crossed levers pivoted together at their point of intersection and having respective upper ends associated with said upper platform, and lower ends associated with said lower platform; rollers provided on said upper ends in rolling engagement with said upper platform, and on said lower ends in rolling engagement with said lower platform; additional lever means comprising additional levers, each of said additional levers having one end portion located at one of said platforms intermediate the lever ends associated therewith, and another end portion pivoted to one of the levers intermediate said point of intersection and the lever ends associated with said one platform; pivot means pivoting said one end portion to said one platform; and mounting means mounting said pivot means for movement substantially parallel to the plane of said platform relative to the latter.

2. An elevator table as defined in claim 1, wherein said mounting means comprises guide means engaging said pivot means for movement of the same substantially normal to the plane of said platform.

3. An elevator table as defined in claim 1, wherein said one platform is said upper platform.

4. An elevator table as defined in claim 1, wherein said one platform is said lower platform.

5. An elevator table as defined in claim l,'wherein said additional lever is pivotable in the general plane of said crossed levers.

6. An elevator table as defined in claim 1; further comprising pivot means pivoting said one end portion to said one platform; and mounting means mounting 6 said pivot means for movement in at least substantial movement of the same. parallelism with the plane of said one platform and in An elevator table as defined in claimq, wherein the general plane of said crossed levers.

7. An elevator table as defined in claim 6; and further I I comprising fluid-operated cylinder-and-piston means 5 cylmderand'plston associated with said pivot means for effecting said said cylinder-and-piston means comprises a hydraulic

Claims

5. An elevator table as defined in claim 1, wherein said additional lever is pivotable in the general plane of said crossed levers.

6. An elevator table as defined in claim 1; further comprising pivot means pivoting said one end portion to said one platform; and mounting means mounting said pivot means for movement in at least substantial parallelism with the plane of said one platform and in the general plane of said crossed levers.

7. An elevator table as defined in claim 6; and further comprising fluid-operated cylinder-and-piston means associated with said pivot means for effecting said movement of the same.

8. An elevator table as defined in claim 7, wherein said cylinder-and-piston means comprises a hydraulic cylinder-and-piston unit.