Technical field

This invention relates to a speed reduction unit of the type which comprises a casing. an output shaft, at least one radial bearing between said shaft and. said casing to rotatively support said shaft in said casing and a consumer associated therewith, and a means of securing said casing on a structure of said consumer.

Background art

As is known, speed reduction units are usually coupled to driven parts with the intermediary of couplings, keyed shafts, hollow-construction shafts, and the like arrangements. Rigid couplings are used in certain applications, an in that case the reduction unit is also to provide support for the driven part. A typical application would be belt conveyors, where a ratio motor is used to drive the belt entrainment drum.

In such applications, or where the speed, reduction unit forms one of the two bearing points between the rotatively driven part and the structure on which this is mounted, it is necessary that comparatively close alignment tolerances be maintained between the bearing points.

This reguires a degree of accuracy which is usually hard to comply with in certain structures, especially where structural work bearing arrangements are involved. Ratio motors of the pendulum type better suit such applications wherein the rotary parts are supported independently, e.g. by means of self-aligning bearings mounted pivotally on the load-bearinα structure and the reduction gear is keyed to the. shaft of said parts and carried thereon in a pendulum fashion. The use of self-aligning bearings is, in fact, preferred there to

confer self-aligning features on the bearing points. However, increased axial space requirements are incurred in that case, especially where epicyclic reduction gears are employed. In addition, πoints must often be provided between the reduction gear output shaft and the rotatively driven shaft which are cost-intensive.

The underlying problem of this invention is to provide a speed reduction unit which s so constructed and operated as to overcome all of the shortcomings with which the above prior art is beset.

Disclosure of invention

This problem is solved according to the invention by a reduction unit as indicated being characterized in that said securing means comprises a swing mount effective to secure said casing on the structure of said consumer in a limited ad ustable manner.

Brief description of drawings

The features and advantages of the invention will become more clearly apparent from the following detailed description of two embodiments thereof, shown by way of example and not of limitation in the accompanying drawings, in which:

Figure 1 is an axial section view through a portion of a mechanical consumer equipped with a reduction unit according to the invention:

Figure 2 is an axial section view through a portion of a mechanical consumer in a modified embodiment of the invention;

Figure 3 is a cross-section view taken along a line III-III in Figure 2.

Modes for carrying out the invention

Generally shown at 1 in the drawing figures is a load-bearing structure of a consumer, e.g. a belt conveyor of which a drum 2 is also shown.

The drum 2 is carried, rotatable about an axis X, on the structure 1 and driven for rotation about said axis from a speed reduction unit 3, only partly depicted in the figures.

The reduction unit 3, which may be a ratio motor, is an epicyclic type having a casing 4 which includes two half-shells 4a,b clamped, together by means of links 5 through an interposed ring gear 6 having an internal toothing 7. In a conventional manner, the. reduction unit further comprises a sun gear 8 keyed to an input shaft 10, and a plurality of planet gears 9 in mesh engagement with both the sun gear 8 and. the toothing 7 of the ring gear 6 .

The planet gears 9 are idlers carried on respective stub shafts 11a of a spider 11. The spider 11 is in turn keyed, to an output shaft 14 of the reduction unit by means of a splined connection 13. This shaft 14 carries, on its remote, end. from the spline connection 13, a flange 15 through which it is attached to the drum 2, and is supported at a sleeve portion 16 of the half-shell 4a in two radial bearings 17, 18 having an oil seal 19 associated therewith. The bearings 17, 18 also function as a second bearing point for the drum 2 by virtue of the rigid connection between the drum 2 and the flange 15 on the. shaft 14, with the first drum bearing point (not illustrated) being located at the axially opposite, end of the drum. It is essential to proper operation of the supports that the two bearings 17, 18 be aligned true along the axis X. Present any inaccuracies in the structure 1, this alignment may turn out to be critical in the instance of conventional reduction gears having their casing attached to the structure 1. Optimum alignment conditions are readily achieved, on the other hand, in the

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reduction unit of Figure 1 by the casing 4 of the reduction unit 3 being attached to the load-bearing structure 1 through an adjustable washer mount generally shown at 20.

The mount 20 comprises a washer 21 having a hemispherical convex surface 22: the washer 21 is formed integrally with the outer shroud of the sleeve portion 16 and is fitted for swinging movement in a convex surface socket 24 of a flanged support 23. For convenience of assembly, the flanged support 23 is made up of two halves 23a,b bonded to each other in a conventional manner. One half 23a is fastened to the structure 1 by means of screws 26.

The casing 4 of the reduction unit 3 is, therefore, let free to swing and align itself to the load-bearing structure 1 within the range of oscillation permitted by the mount 20, but is not allowed to rotate, any rotation being resisted by a reaction arm 28 which has a first end attached to one of the links 5 and a second opposite end 29 attached to the structure 1.

The example shown in Figures 2 and 3 mainly differs from the previous one by the shape of the adjustable washer mount, generally denoted here by the numeral 30. Similar parts to those of the previous example, are denoted by the same reference numerals. Another difference comes from the coupling arrangement of the output shaft 14 to a collar 33 on the drum 2 including a key 31.

The mount 30 comprises a washer 34 fitted over the outer shroud of the sleeve portion it. of the half-shell 4a, which washer is clamped for oscillation within a hemispherical surface socket 35a on an upright support 35. The support 35 is a split construction with the two halves held together by screws 36.

In either of the examples described, by having the casing of the reduction unit 3 attached to the load-bearing

structure 1 of the consumer, the output shaft 14 bearings can be used to hold, at least one of the axial ends of the rotating part of the consumer corresponding to the drum 2. Concurrently therewith, the provision of an adjustable support through which the casing of the reduction unit is attached to the consumer enables any alignment error to be accommodated between the bearing points.