FORM - 2 THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10; rule 13)
POWER TRANSMISSION DEVICE
EMERSON ELECTRIC CO.,
U. S. Company of 8000 West Florissant Avenue, ST. Louis, Missouri 63136, USA
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF THE INVENTION:
This invention relates to power transmission device. In particular this invention relates to gear couplings provided with brake discs. More particularly this invention relates to a device for limitation of axial float of a gear coupling provided with disc brake.
BACKGROUND OF THE INVENTION:
Couplings are used in power transmission drives to connect shafts. Typically torque produced by a motor, engine or such rotating machinery is transferred from a driving shaft to a driven shaft by the use of a coupling. These couplings may be classified in two broad groups; rigid couplings and flexible couplings. Flexible couplings permit connecting of shafts that have misalignments. Gear couplings are classified as flexible couplings and essentially consist of two hubs having gear teeth machined on their external surface and two flanged sleeves having complementary teeth machined on their internal surface. The hubs are mounted on the driver and driven shafts with suitable key and key ways. The sleeves engage the respective hubs at the tooth profile and are bolted to each other.
Types of misalignment that are effectively accommodated by gear couplings are:
(a) Axial- shafts are aligned but the shaft ends are apart from each other.
(b)Parallel offset- axes of the shafts are parallel but not in the same straight
line.

(c) Angular- axes of shafts intersect at centre point of the coupling, but not in the same straight line.
(d) Combined angular offset- axes of the shaft do not intersect at the centre point of the coupling and are not parallel.
The gear coupling is a steel double joined coupling that accommodates the misalignment through the sliding of mating gears. The gear teeth are precision machined guaranteeing uniform contact on all the teeth. Crowned teeth gear couplings wherein the hub gear is provided with a radius on the mating surface are flexible enough to accommodate larger misalignment and axial movements.
Advantages of using gear couplings are:
(i) maximum torque capacity due to large pitch circle diameter of the
gears; (ii) larger permissible hub bores; (iii) higher permissible additional loads for staring; (iv) higher permissible peak torque.
Gear couplings are generally filled with grease to reduce friction and wear. O-ring or paper gasket seals are provided in the sleeves / covers to prevent any grease leakage.
Gear couplings are extensively used in Iron and Steel, Pulp and paper, Mining, and Cement industries.

In certain applications requiring quick stopping of the driven shaft, a brake disc (or a brake shoe) is included in the coupling and an external braking force is applied on the disc to quickly stop the driven shaft after the motive power is disengaged by a suitable clutch arrangement. These couplings are referred to as "Brake disc gear couplings". The brake disc is invariably an annular disc clamped between the sleeves of the couplings. In certain applications axial expansion of the shaft due to thermal changes takes place. Also driven machines have axial movement due to their design. Such an axial movement takes place in a gear coupling by the relative sliding of the hub and sleeve with respect to one other. However in certain applications it is necessary to limit the above movement within a preset permissible range, by providing an axial limitation feature.
In some of the conventional brake disc gear coupling the axial limitation feature is provided by machining semi circular projection on either faces of the brake disc positioned between the hubs. Alternatively a spacer is provided as a separate component between the hubs to provide axial limitation of the shaft. Still alternatively the brake disc could be circular disc positioned between the hubs to act as stopper. All these above alternatives are not cost effective as it involves usage of thicker materials and more machining. Additional weight of the disc brakes also causes dynamic imbalances leading to vibrations and higher operational noise levels. In view of the above shortcomings it is necessary to provide an axial limitation feature for a disc brake gear coupling.

OBJECT OF THE PRESENT INVENTION:
One of the objects of this invention is to provide an axial limitation device for a gear coupling with brake disc that uses lower thickness materials as compared to the conventional devices.
Another object of this invention is to provide an axial limitation device for a gear coupling with brake disc that involves simple and inexpensive machining
procedures.
Yet another object of this invention is to provide an axial limitation device for a gear coupling with brake disc which does not increase the overall mass of the coupling.
Yet another object of this invention is to provide an axial limitation device for a gear coupling with brake disc which is stable for a wide range of gear couplings.
Yet another object of this invention is to provide an axial limitation device for a gear coupling with brake disc which is range adjustable easily.
Another object of this invention is to provide an axial limitation device for a gear coupling with brake disc which is easy to install.
Yet another object of this invention is to provide an axial limitation device for a gear coupling with brake disc which could be installed at site conditions with out the use of expensive tools, jigs and fixtures.

SUMMARY OF THE INVENTION:
In accordance with this invention there is provided an axial limitation device for a gear coupling with brake disc comprising:
(i) two hubs provided with external gear teeth; the hubs adapted to be removably fitted to a driving shaft and driven shaft respectively;
(ii) two flanged sleeves provided with complementary internal gear teeth; said sleeves adapted to be slidingly fitted over the hubs in such a manner that in the operative configuration the flanges are adapted to be fastened together and the internal gear teeth and the external gear teeth engage one another;
(iii) an annular brake disc adapted to be fastened between the sleeves; and
(iv) at least one axial limitation element fitted on the brake disc; said at least one element positioned between said hubs in the operative configuration.
Typically, said axial limitation element is removably secured to the brake disc.
Typically, the external gear teeth provided on the hubs have radius along the hub axis.
Typically, lubricant retention seals are provided between the hubs and the sleeves.

Typically, the seal is made of material selected from a group of materials consisting of paper, natural or synthetic rubber, resilient polymers and combination thereof.
Typically, the axial limitation element is selected from a group of elements consisting of round headed pin, flat headed pin and dowel pin.
Typically, at least one opening is provided on the brake disc complementary to said at least one element; said opening adapted to allow press fitting of said element.
Alternatively, at least one opening is provided on the brake disc complementary to said at least one element; said opening adapted to allow threaded fitting of said at least one element.
Alternatively, said at least one element is a metallic protuberance formed on the brake disc.
DESCRIPTION OF THE INVENTION:
The invention will now be described with reference to accompanying drawings in which:
Figure - 1 is a sectional elevation of a conventional gear coupling with brake disc provided with disc brake having semi circular projection machined on either faces of the disc;

Figure 2 is a sectional elevation of a gear coupling with brake disc of this invention provided with an axial limitation device;
Figure 3 is an enlarged sectional view of the gear coupling with brake disc provided with an axial limitation device as shown in figure 2;
Figure 4 is a sectional elevation of a round head button axial limitation device fitted on the gear coupling with brake disc of this invention as shown in figure 2;
Figure 5 is a sectional elevation of an alternative embodiment in the form of a flat head circular button axial limitation device fitted on the gear coupling with brake disc of this invention as shown in figure 2;
Figure 6 is a sectional elevation of an alternative embodiment in the form of a threaded round head button axial limitation device fitted on the gear coupling with brake disc of this invention as shown in figure 2;
Figure 7 is a sectional elevation of an alternative embodiment in the form of a welded projection button axial limitation device fitted on the gear coupling with brake disc of this invention as shown in figure 2;
Figure 8 is a sectional elevation of an alternative embodiment in the form of a hardened dowel pin button axial limitation device fitted on the gear coupling with brake disc of this invention as shown in figure 2; and

Figure 9 is a sectional elevation of an alternative embodiment of the invention wherein the axial limitation device is fitted on the hubs.
DETAILED DESCRIPTION OF THE PRESENT INVENTION: Referring to figure 1 a conventional gear coupling with brake disc is indicated generally by the reference numeral 50. The disc brake gear coupling 50 consists of two hubs (1) provided with external gear teeth (9). Two flanged sleeves (3) provided with internal gear teeth (13) are slidingly fitted over the hubs and bolted to one other using fasteners (5). Disc brake (7) in the form of an annular disc is positioned between the sleeves. The disc brake (7) is provided with semi circular raised machined portion (11) on either side of the disc faces, adjacent to the inner edge of the disk brake (7), to limit the axial movement of the hubs (1) to a predetermined limit. The conventional disc brake of this type has to be machined from a higher thickness plate material. The radius of the semi circular portion determines the limiting value of the axial movement and has to be uniquely machined to suit a particular design parameter and once machined can not be altered easily with out major modification or replacement of the entire brake disc.
Referring to figure 2 the gear coupling with brake disc of this invention provided with an axial limitation device is indicated generally by the reference numeral (100). The disc brake gear coupling 100 consists of two hubs (51) provided with external gear teeth (59). Two flanged sleeves (53) provided with internal gear teeth (55) are slidingly fitted over the hubs and bolted to one other using fasteners (57). Disc brake (61) in the form of an annular disc is positioned between the sleeves. The disc brake (61) is provided with a round head button (63) axial limitation device on either side of the disc faces, adjacent to the inner

edge of the disk brake (61), to limit the axial movement of the hubs (51) to a predetermined limit. The round head button axial limitation device (63) is press fitted in holes drilled adjacent to the inner edge on the disc brake. This device is easily manufactured and stored in standard sizes suitable for a wide range of movement limitation requirement of different applications having different limitation parameters. Replacement of this device can be carried out easily even at site conditions by person of ordinary skill level and with out resorting to machining of any of the coupling components.
Figure 3 is an enlarged view of the round head button (63) axial limitation device fitted on the brake disc (61).
Figure 4 is another enlarged view of the round head button (63) axial limitation device fitted on the brake disc (61).
Figures 5, 6, 7 and 8 are alternative embodiments of axial limitation device. A flat head circular button axial limitation device (71) is shown in figure 5. A threaded round head button axial limitation device (73) is shown in figure 6. A welded projection button axial limitation device (75) is shown in Figure 7. A hardened dowel pin button limitation device (77) is shown in figure 8.
Figure 9 is an axial limitation device located on the operative inner face of hubs (51). Any of the alternative buttons shown in figure 5, 6, 7 or 8 could be used in this embodiment of the invention.

While considerable emphasis has been placed herein on the particular features of the preferred embodiment and the improvisation with regards to it, it will be appreciated the various modifications can be made in the preferred embodiments without departing from the principles of the invention. These and the other modifications in the nature of the invention will be apparent to those skilled in art from disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to interpreted merely as illustrative of the invention and not as a limitation.

We Claim:
[1] A device for limitation of axial float of a gear coupling provided with a
brake disc; said device comprising:
(i) two hubs provided with external gear teeth; the hubs adapted to be removably fitted to a driving shaft and driven shaft respectively;
(ii) two flanged sleeves provided with complementary internal gear teeth; said sleeves adapted to be slidingly fitted over the hubs in such a manner that in the operative configuration the flanges are adapted to be fastened together and the internal gear teeth and the external gear teeth engage one another;
(iii) an annular brake disc adapted to be fastened between the sleeves; and
(iv) at least one axial limitation element fitted on the brake disc; said at least one element positioned between said hubs in the operative configuration.
[2] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 1, wherein said elernent is removably secured to the brake disc.
[3] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim I, wherein said external gear teeth provided on the hubs have radius along the hub axis.

[4] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 1, wherein lubricant retention seals are provided between the hubs and the sleeves.
[5] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 3, wherein the seal is made of material selected from a group of materials consisting of paper, natural or synthetic rubber, resilient polymers and combination thereof.
[5] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 1, wherein said axial limitation element is selected from a group of elements consisting of round headed pin, flat headed pin and dowel pin.
[6] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 5, wherein at least one opening is provided on the brake disc complementary to said at least one element; said opening adapted to allow press fitting of said element.
[7] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 5, wherein at least one opening is provided on the brake disc complementary to said at least one element; said opening adapted to allow threaded fitting of said at least one element-
[8] A device for limitation of axial float of a gear coupling provided with a brake disc as claimed in claim 1, wherein said at least one element is a metallic protuberance formed on the brake disc.

[9] A device for limitation of axial float of a gear coupling provided with a brake disc as described herein above with reference to the accompanying drawings.