Drive unit for a conveyor of the tube-encased cable type with spaced-apart conveying elements, for materials of fluid behavior

A drive unit for distribution systems for materials of fluid behavior, such as livestock feed materials, in which a cable provided with spaced-apart conveying elements is caused to slide inside a tube, said drive unit being of the type comprising a geared motor, on the output shaft of which there is fixed a toothed wheel about which the cable winds. The geared motor is mounted on a supporting structure in a freely oscillating manner such that as the tension in the slack branch of the cable varies, the position of the axis of the toothed wheel varies by virtue of its rotation about an axis passing essentially through the point of tangency between the toothed wheel and the taut branch of the cable.

BACKGROUND OF THE INVENTION 
This invention relates to an improved drive unit for conveyors for 
materials of fluid behaviour, such as feed metarials in livestock rearing 
stations, where the conveyor is of the type comprising a cable on which 
there are fitted spaced-apart conveying elements in the form of discs or 
fins, the cable being made to slide endlessly inside a tube so as to 
discharge the feed material into feeding troughs from which the animals 
eat. 
As is well known to experts in this particular art, one of the problems to 
be solved in designing systems of this kind is the problem of tension 
variations in the cable. The degree of cable tension is subject to 
variation both during the operation of the system due to variations in the 
load applied to it, and by virtue of the elongation which occurs with 
time, and which is particularly felt in systems of a certain length. 
In seeking to automatically take-up these cable tension variations, the 
main approach has been to provide deviation pulleys mounted in a floating 
manner and subjected to the action of return springs or counter-weights. 
However, such arrangements have not given completely satisfactory results, 
in particular because they make the system drive unit rather bulky and 
more costly. 
SUMMARY OF THE INVENTION 
The object of the present invention is therefore to obviate the aforesaid 
technical problem by providing a drive unit which itself incorporates a 
system able to automatically and adequately take-up tension variations in 
the conveyor cable, without requiring the use of bulky and costly 
auxiliary members additional to those which form the structure of the unit 
itself. 
This object is attained according to the present invention by a drive unit 
for distribution systems for materials of fluid behaviour, such as 
livestock feed materials, in which a cable provided with spaced-apart 
conveying elements is caused to slide inside a tube, said drive unit being 
of the type comprising a geared motor, on the output shaft of which there 
is fixed a toothed wheel about which said cable winds, and being 
characterised in that the geared motor is mounted on a supporting 
structure in a freely oscillating manner such that as the tension in the 
black branch of the cable varies, the position of the axis of said toothed 
wheel varies by virtue of its rotation about an axis which passes 
essentially through the point of tangency between the toothed wheel and 
the taut branch of the cable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the drawings, a drive unit constructed in accordance with 
the principles of the invention is indicated overall by 10, and comprises 
an essentially box-like casing 11 for supporting and containing an 
assembly consisting of a motor 12 and reduction gear 13 which, by way of a 
toothed wheel 14, drives a tube-encased disc-type conveyor cable 15, of 
the kind well known in the livestock field. 
According to the present invention, the assembly comprising the motor 12 
and reduction gear 13 is mounted to freely oscillate about a shaft 16 
which rotates on end journals 17 housed in respective cradles 18 provided 
in opposing walls 19 of the box casing 10. Preferably there is provided a 
plurality of pairs of cradles 18 formed along slots 20, so as to be able 
to mount the geared motor assembly inside the casing 10 in the most 
suitable position according to the tension in the cable 15. 
As can be clearly seen from the drawings, the shaft 16 is fixed to the top 
of the reduction gear 13 in a position radial to the toothed wheel 14. 
The drive shaft 21 projects through a wide slot 22 from the geared motor 
containing chamber defined by the opposing walls 19. In this manner, the 
drive shaft 21 is free to move along the slot 22 in a curved line 
trajectory when the shaft 16 rotates either clockwise or anti-clockwise. 
In this manner it is apparent that any tension variation in the cable 15 is 
taken-up by oscillation of the drive shaft 21, and thus by a movement of 
the toothed wheel 14, determined by the counterweight due to the motor 12. 
In this respect, it should be noted that the fact that the shaft 16 passes 
through the point of tangency of the taut upper branch 24 of the cable 15 
means that the action of this branch has practically no influence on the 
system equilibrium. 
It is also apparent that the shaft 21 will move towards the right along the 
slot 22 (for example from the position of FIG. 1 to the position of FIG. 
5) if the slack in the lower branch 23 increases, due for example to an 
overload, for example on starting the system, or to cable elongation 
induced by time fatigue. 
In contrast, if the load on the slack branch 23 reduces, the drive shaft 21 
and thus the wheel 14 will move towards the left. The invention therefore 
provides a drive unit for a tube-encased cable conveyor for materials of 
fluid behaviour, which advantageously incorporates a system for taking-up 
any cable tension variations, which uses no auxiliary means additional to 
the geared motor, its supporting structure and its container, but instead 
uses a particular and original mounting arrangement for said geared motor, 
which can oscillate relative to said casing. 
The drive unit according to the invention, which is described and 
illustrated herein by way of non-limiting example only, is of the type 
suitable for vertical positioning, i.e. for systems in which the taut and 
slack branches of the conveying cable pass parallel to each other about 
the toothed drive wheel, which rotates about a horizontal axis, the 
pivoting axis of the geared motor also being horizontal. However, the 
principle of the invention is also applicable to drive units in which both 
the axis of rotation of the toothed drive wheel and the pivoting axis of 
the geared motor are vertical. In this case, a counteracting spring 25 
indicated by dashed and dotted lines in FIG. 4 cooperates with the geared 
motor.