Tracked drive device

The tracked drive device particularly protected by its frame or hood as well as by protective plates, so as to prevent any accidental insertion of a finger or any other part of the human body between the track elements. The arrangement makes access to the track, for replacement or maintenance, particularly difficult. The invention provides a pivoting construction of the driving device, whereby the driving mechanisms become easily accessible, thus facilitating track change.

The present invention concerns slender drive element devices, in particular those provided with drive tracks in the form of endless chains or belts, able to drive the said slender elements in a translation movement, the invention more particularly concerning the means facilitating access to the said endless chains or belts in order to facilitate the changing thereof.

BACKGROUND OF THE INVENTION

A particular case of a drive device as described in general terms above is a tracked drive device provided for driving cables, tubes or other elements with an essentially cylindrical cross-section in a longitudinal translation movement.

The U.S. Pat. No. 5,884,384 describes a method of placing, by blowing, one or more empty cables or tubes in a tube laid in the ground. The device used for this purpose comprises two endless chains, each carrying a plurality of drive pieces disposed successively on the chain, and depicted for example in U.S. Pat. No. 2,679,924, each of the said drive pieces being provided with a driving sole plate having a form adapted to the element or elements to be driven. A rectilinear length of each of the chains circulates in parallel, facing the corresponding length of the other chain, the element or elements to be driven being clamped between the driving sole plates of the drive pieces facing each other.

Since the driving sole plates mounted on the chains have a form and dimensions adapted to the element or elements to be driven, it is necessary to change the said sole plates or respectively to change the chain, at each change of form or dimension of the element to be placed.

Moreover, safety standards require that each of the two chains as well as the drive pieces and sole plates be housed in frames, casing or hoods, arranged so that it is impossible to accidentally slide therein a finger or any other part of the human body, so as to prevent any injury.

This latter requirement therefore makes it difficult to gain access to the chains in order to be able to remove them so as to exchange them for chains provided with drive pieces or respectively sole plates having a form and dimensions adapted to the next product to be placed.

SUMMARY OF THE INVENTION

The aim of the present invention is therefore to propose a device for driving slender elements arranged so that the removal and mounting of the drive means are facilitated thereby.

This aim is achieved by drive devices as described herein and equivalents thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The device1for driving a slender element2, here a cable, is generally associated, as can be seen inFIG. 1, with a first device3for measuring speed and placing length, as well as a device4for injecting a fluid responsible for introducing a flow of the fluid inside a tube20assisting with the placing of the cable2inside the tube20. This placing method being known, it will not be described more precisely here.

FIG. 1shows that the drive device1is composed of a top portion10and a bottom portion11, the two portions being held together by means12for fixing together the two portions and adjusting the separation of the drive mechanism according to a known technique. Consequently the means12make it possible to disconnect the two portions10and11in order to obtain two separate portions, as can be seen in the following figures.

In operation, as can be seen inFIG. 1, the two frames, casings or hoods100and110of the top10and bottom11portions have their edges facing each other directly in contact or very close to each other, generally leaving no space or a minimum space between the said portions. For the cases where, over an interface length between the two portions, there would be too much space remaining, it can be seen inFIG. 3that the drive mechanism is also protected by two lateral plates118thus providing complete safety for the device against any accidental intrusion of a finger or any other part of the human body.

Since the drive mechanisms are thus deeply sunk in the frames, access to the drive chains for removing and exchanging them is difficult.

The drive mechanisms101or respectively111of each of the two portions10and11each comprise, as can be seen inFIGS. 2 and 3, a chassis102, or respectively112, carrying two toothed wheels on its ends, a first one120or respectively130visible in partial sections inFIG. 1, each mounted on a spindle121or respectively131directly driven by a motor103or respectively113, the second toothed wheel104or respectively114serving as a return wheel for the endless chain105or respectively115, on which there are mounted the drive pieces1050provided with driving sole plates1051as described previously, the mechanism is completed by a device for the mechanical tensioning of the endless chain, consisting, according to this embodiment of a stirrup106or respectively116, fixed firstly to the spindle of the toothed return wheels104or respectively114, and provided with a threaded rod able to be inserted in a corresponding opening in the frame100or respectively110, the tensioning being provided by the tightening of a bolt on the said threaded rod. In this embodiment of the clamping device, at least one of the housings for the spindles carrying t he toothed wheels is oblong so as to allow the said tensioning of the drive chain.

According to another embodiment of the mechanical tensioning device for the endless chain, this, not shown in the figures, is directly mounted on the chassis102and112and is able, by a known means with an adjustment screw and/or a knuckle joint, to slightly bring together or separate the spindles of the toothed wheels, thus putting the chain under tension.

Pins107or respectively117pass through holes provided on the one hand in the frames100and110serving to keep the chassis102or respectively112in place, each in its respective frame.

As mentioned previously, one of the portions of the drive device, here the bottom portion, advantageously comprises, on its drive mechanism111, two protective plates118, disposed on each side of the said mechanism and blocking any openings between the two frames, as can be seen inFIG. 1. Each of the said protective plates preferably comprises an extension119on its end closest to the end for insertion of the slender element2, so as to prevent the introduction of a finger or any other portion of the human body through this insertion opening.

For changing the drive chains, it suffices now to separate the measuring3and blowing4devices of the drive device1, and then to separate the top portion10from the bottom portion11of the said device, as a result of which, for each of the portions, by relaxing the chain and removing the pins107and117, it is possible to make each of the drive mechanisms pivot about its drive spindle, as depicted inFIGS. 2 and 3, thus making the chains105and115directly accessible in order to be removed in a conventional manner. The mounting of the new chains takes place exactly in the reverse order of what has just been described.

The facilitated access means to the drive mechanism have been described above for a mechanism for driving an endless chain provided with drive pieces each comprising a driving sole plate. It is clear that similar facilitated access means can also be provided when the drive mechanism comprises a belt, flat or shaped, which it may also be necessary to change. Likewise, these facilitated access means have been described as making the drive mechanisms pivot about drive spindles; although this arrangement is advantageous, it would be just as possible to make the mechanisms pivot about the return spindles. Moreover it is obvious that the fixing and clamping device12as described previously is not essential to the arrangement and that it can be designed differently from what has been described here. And finally, such facilitated means of access to a tracked drive mechanism can be used for devices for driving slender elements other than the one described above solely by way of example.