RACK-TYPE KINEMATIC MECHANISM, IN PARTICULAR FOR VEHICLE LIFTS

Abstract: A description is provided of a rack-type kinematic mechanism (10), in particular for vehicle lifts, comprising a first , fixed rack (20), and a second rack (24) which is mobile and supports a lifting unit (26), and a toothed wheel (18), which is interposed between the said racks (20, 24) at the opposite ends of the latter. When the toothed wheel (18) is pivoted on the end of the rod (14) of a cylinder (12), the lifting unit (26) travels a path which is twice that of the rod (14), such that the cylinder can have respective dimensions which are reduced by half, for the same lifting path.

Description: Title: "RACK-TYPE KINEMATIC MECHANISM, IN PARTICULAR FOR VEHICLE LIFTS" TEXT OF THE DESCRIPTION The present invention relates to a rack-type kinematic mechanism, in particular for vehicle lifts. In the mechanical engineering field, various types of vehicle lifts are known, which are in use in mechanical engineering workshops and similar environments, in order to provide convenient access to the parts beneath the vehicle. Thus, lifts have been developed with columns which are on view, in which the rails, runways or arms to support the vehicle are translated along two or four uprights, which are secured vertically to the floor; recessed column-type lifts, which are similar to the previous type, but in which the columns are at least partially embedded below the floor; and finally lifts with scissors-type articulation, which are preferably also recessed, in which the vertical movement of the rails or the like is provided by a scissors-type articulation disposed at the base. Irrespective of their type, the lifts always contain cylinders, which are normally of the oleodynamic type, and are designed to move the lift. In the known lifts, the kinematic mechanism is such as to require substantial cylinder dimensions, with consequent disadvantages in terms of dimensions when the lift is lowered, and of costs. The object of the present invention is to provide a rack-type kinematic mechanism, particularly for vehicle lifts, which permits use of oleodynamic cylinders with smaller dimensions, for the same ratio between the maximum height of lifting and size when the lift is lowered, i.e. in other words, which makes it possible to obtain a better ratio for the same dimensions of the oleodynamic cylinders . This problem is solved remarkably well by means of a rack-type kinematic mechanism according to claim 1. Further advantageous characteristics of the said kinematic mechanism are indicated in the dependent claims. The characteristics, objects and advantages of the present invention will become more apparent from the following description and the attached drawings, relative to a non-limiting embodiment, in which the same reference numbers indicate parts which are the same or equivalent. In the various figures: Figure 1 is a lateral view of a rack- type kinematic mechanism according to the present invention, in the lowered position; and Figure 2 is a lateral view of the rack-type kinematic mechanism in the raised position. The figures illustrate schematically a rack- type kinematic mechanism 10 according to the invention, applied purely by way of example to a column-type lift. The kinematic mechanism 10 comprises a cylinder 12, for example of the oleodynamic type, on the free end of the rod 14 of which a fork 16 is provided. A toothed wheel 18 is pivoted in the fork 16. The toothed wheel 18 engages on one side with a first rack 20, which for example is secured to a column 22 of the lift. The toothed wheel 18 engages on the opposite side with a second rack 24, which is also supported and guided by a column (not shown) . A lifting unit 26, for example a lifting arm 26 or part of a lifting rail, is secured to the rack 24. The pitch and toothing of the toothed wheel 18 and of the two racks 20, 24 are identical. As illustrated in the figures, in addition, the arrangement of the toothed wheel 18 and of the two racks 20, 24 is such that at the end of travel, the latter are disposed on opposite sides relative to the toothed wheel 18. It will be appreciated that in the functioning of the kinematic mechanism 10 according to the invention, the first rack 20 acts as a point of engagement for the kinematic mechanism 10, and as can be seen by comparing the figures, the lifting unit 26 which is connected to the second rack 24 travels a path which is twice that of the path * travelled by the rod 14 of the cylinder 12. Thus, for the same lifting path of the lifting unit 26, the cylinder 12 used can have dimensions which are reduced by half in comparison with the known configurations of lifts, such that the rack-type kinematic mechanism according to the invention eliminates fully the above-described problems, by providing a lifting mechanism which is more economical and functional. Although in the embodiment described and illustrated above, the rack-type kinematic mechanism is fitted to a column-type lift, it is apparent that it can also be fitted to scissors-type lifts, by means of purely structural modifications which are within the capability of any average person skilled in the art . It is apparent that numerous modifications, adaptations, completions, variants and replacements can be made to the embodiment previously described by way of illustrative, non-limiting example, without departing from the scope of the invention, as determined by the following attached claims. For example, instead of being pivoted on the end of the rod 14, the toothed wheel 18 could be connected to a rotary output of a floating two-way motor.

Claims: CLAIMS 1. Rack-type kinematic mechanism (10), in particular for vehicle lifts, comprising a first, fixed rack (20) , and a second rack (24) which is mobile and supports a lifting unit (26) , and a toothed wheel (18) , which is interposed between the said racks (20, 24) at the opposite ends of the latter, the said toothed wheel (18) being integral with the movement means for the lift, such that the said lifting unit (26) travels a path which is twice that of the movement means for the lift. 2. Kinematic mechanism (10) according to claim 1, characterised in that the said movement means for the lift consist of an oleodynamic cylinder (12) . 3. Kinematic mechanism (10) according to claim 2, characterised in that the said toothed wheel (18) is pivoted (16) on the end of the rod (14) of the said cylinder (12) . 4. Kinematic mechanism (10) according to claim 1, characterised in that the said toothed wheel (18) is pivoted on a rotary output of a floating two-way motor. 5. Kinematic mechanism (10) according to one or more or the preceding claims, characterised in that the said racks (20, 24) and the said toothed wheel (18) have the same pitches and toothing.

Inventors: GRANATA TEBALDO, GRANATA, TEBALDO
Applicants: GRANATA TEBALDO, SNAP ON TECH INC, GRANATA, TEBALDO, SNAP-ON TECHNOLOGIES, INC.
Application year: 1999
Main classification: F16H19
IPC codes: B66F7, F16H19