FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Shaft Locking Mechanism for Slip Ring HT Motors
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Das Mukul of Crompton Greaves, Machine (M7) Division, D-5, Industrial Area, MPAKVN, Mandideep - 462046, Madhya Pradesh, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed.

FIELD OF INVENTION:
This invention relates to slip ring High Tension motors.
More particularly, the invention relates to a locking mechanism for locking shaft of slip ring motors, and slip ring motors with locked shaft, thereof.
BACKGROUND OF INVENTION:
An electric motor converts electrical energy to mechanical energy. It includes a stator and a rotor. A slip ring (in electrical engineering terms) is a method of making an electrical connection through a rotating assembly.
A squirrel cage rotor is the rotating part used in the most common form of AC induction motor. An electric motor with a squirrel cage rotor is termed a squirrel cage motor.
A slip ring motor or wound-rotor motor is a type of induction motor. The rotor windings are connected to a slip ring, which makes it different from the squirrel-cage rotor. The rotor can be connected to external resistances, which allows controlling the speed and speed/torque characteristic of the motor.
Previously, shaft locking arrangement was being used for squirrel cage motors. The locking was being done in between the shaft end and end shield. However, in a slip ring motor, this was earlier not possible as the space was being occupied by the slip ring.

In slip ring motors, it has been observed that the shaft runs out due to its non-locked manner, during transportation. Hence, there is a need for a locking arrangement for locking the shaft of a slip-ring motor.
OBJECTS OF INVENTION:
An object of the invention is to provide a new and improved arrangement for shaft locking in slip ring HT motors.
Another object of the invention is to provide a new and improved arrangement which can facilitate a new mechanism for shaft locking in slip ring HT motors in a more efficient manner.
Yet another object of the invention is to provide a new and improved arrangement which can facilitate a new mechanism for shaft locking in slip ring HT motors in a cost effective manner.
Yet another object of the invention is to provide a new and improved arrangement which can facilitate a new mechanism for shaft locking in slip ring HT motors in a more robust manner.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a shaft locking mechanism for fan covers of motors, said fan cover including a co-planar mounted fan at its one end and an elongate conduit adapted to guide air from said fan, said fan being mounted on a shaft, characterised in that, said mechanism comprises an elongate channel adapted to be co-axially mounted with respect to said shaft at the external distal end of said shaft, thereby preventing axial movement of said shaft.

According to this invention, there is also provided a slip ring motor with shaft locking mechanism for fan covers of said slip ring motor, said fan cover including a co-planar mounted fan at its one end and an elongate conduit adapted to guide air from said fan, said fan being mounted on a shaft, characterised in that, said mechanism comprises an elongate channel adapted to be co-axially mounted with respect to said shaft at the external distal end of said shaft, thereby preventing axial movement of said shaft.
Typically, said channel is a slit channel said slit positioned along said channel length, and located at lateral ends of said channel.
Typically, said mechanism includes at least a pair of boss elements located on the fan cover and at least a pair of corresponding stud elements adapted to fit its one end with a corresponding boss element and further adapted to fit its other end through said slit of said channel by positioning itself at an appropriate location in the channel slit so as to derive sufficient locking of the shaft.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates an auxiliary view of the fan cover with shaft locking mechanism;
Figure 2 illustrates a front view of the fan cover with shaft locking mechanism;

Figure 3 illustrates a side view of the fan cover with shaft locking mechanism;
Figure 4 illustrates a top view of the fan cover with shaft locking mechanism;
Figure 5 illustrates am auxiliary sectional view of the fan cover with shaft locking mechanism; and
Figure 6 illustrates a side sectional view of the fan cover with shaft locking mechanism.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to the invention there is envisaged a new and improved arrangement which can facilitate a new mechanism for shaft locking in slip ring HT motors.
Figure 1 illustrates an auxiliary view of the fan cover with shaft locking mechanism.
Figure 2 illustrates a front view of the fan cover with shaft locking mechanism.
Figure 3 illustrates a side view of the fan cover with shaft locking mechanism;
Figure 4 illustrates a top view of the fan cover with shaft locking mechanism.
Figure 5 illustrates am auxiliary sectional view of the fan cover with shaft locking mechanism.
Figure 6 illustrates a side sectional view of the fan cover with shaft locking mechanism.

A fan cover (16), of a slip ring motor (not shown), with a fan and guiding conduit is shown.
In accordance with an embodiment of this invention, there is envisaged a locking mechanism which comprises an elongate channel (14) adapted to be co-axially mounted to the shaft (18) at the external distal end of the shaft (18). This securing of the channel (14), in co-axial manner and in place, with the fan cover (16) is by means of boss (12) and stud (20) mechanism. The ends of the channel are enabled to receive the studs (20) which mate with the boss (12) fitted on to the exterior of the fan cover (16). The ends of the channel have slits (22) through which the studs (20) pass. The studs (20) are, hence, allowed lateral movement.
This lateral movement provides an arrangement which is modular, in that, it can be adjusted to provide an adjustable grip on the shaft.
In this invention, the back plate of the fan cover is used to provide an arrangement for shaft locking. So this type of arrangement is completely new for slip ring induction motors.
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. A shaft locking mechanism for fan covers of motors, said fan cover including a co-planar mounted fan at its one end and an elongate conduit adapted to guide air from said fan, said fan being mounted on a shaft, characterised in that, said mechanism comprises an elongate channel adapted to be co-axially mounted with respect to said shaft at the external distal end of said shaft, thereby preventing axial movement of said shaft.
2. A mechanism as claimed in claim 1 wherein, said channel is a slit channel said slit positioned along said channel length, and located at lateral ends of said channel.
3. A mechanism as claimed in claim 1 wherein, said mechanism includes at least a pair of boss elements located on the fan cover and at least a pair of corresponding stud elements adapted to fit its one end with a corresponding boss element and further adapted to fit its other end through said slit of said channel by positioning itself at an appropriate location in the channel slit so as to derive sufficient locking of the shaft.
4. A mechanism as claimed in claim 1 wherein, said motor is a slip ring motor.
5. A slip ring motor with shaft locking mechanism for fan covers of said slip ring motor, said fan cover including a complanar mounted fan at its one end and an elongate conduit adapted to guide air from said fan, said fan being mounted on a shaft, characterised in that, said

mechanism comprises an elongate channel adapted to be co-axially mounted with respect to said shaft at the external distal end of said shaft, thereby preventing axial movement of said shaft.
6. A motor as claimed in claim 5 wherein, said channel is a slit channel said slit positioned along said channel length, and located at lateral ends of said channel.
7. A motor as claimed in claim 5 wherein, said mechanism includes at least a pair of boss elements located on the fan cover and at least a pair of corresponding stud elements adapted to fit its one end with a corresponding boss element and further adapted to fit its other end through said slit of said channel by positioning itself at an appropriate location in the channel slit so as to derive sufficient locking of the shaft.