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
A machine for testing the performance of an AC motor
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400
030, Maharashtra, India, an Indian Company
INVENTOR
Bhujbal Eknath, Crompton Greaves Ltd, LT Motors Division (M3), A-6/2 MIDC, Ahmednagar 414001, Maharashtra, India, an Indian national
PREAMBLE TO THE DESCRIPTION
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 a machine for testing the performance of an AC
motor.
BACKGROUND OF THE INVENTION
A machine for testing the performance of an AC motor like AC induction motor comprises a support structure having an upright support mounted on a base. The upright support comprises an inner support member held in an outer support member with the lower end of the inner support member supported on a crosspin engaged across the outer support member. The inner support member comprises a crescent shaped support bracket at the top thereof. The machine also comprises a drive shaft (carden shaft) with a forked portion at each of the driven end and drive end thereof. The drive shaft also comprises a pair of mounting flanges one at each of the driven end and drive end thereof joined to the forked ends with a knuckle joint formed with a bolt. The drive shaft also has a pair of hubs each at each end thereof mounted to the respective mounting flange. Each of the hubs has a central bore. The drive shaft is mounted in the crescent shaped bracket at the centre of the drive shaft. The drive shaft has at the driven end thereof a drive motor mounted on a mounting block with the drive motor shaft engaged in the central bore of the respective hub and coupled thereto usually with a key and keyway arrangement. The drive shaft has at the drive end thereof the AC motor to be tested mounted on a mounting block with the AC motor shaft engaged in the central bore of the respective hub and coupled thereto usually with a key and keyway arrangement.
The hubs are very heavy and generally each weighs about 60 to 70 kg. When the hub at the drive end of the drive shaft is not coupled to the AC motor shaft, it always

hangs down about the respective bolt. At the time of testing the AC motor, the hub at the drive end of the drive shaft has to be manually lifted up and aligned with the AC motor shaft and held in that position so as to engage the AC motor shaft in the central bore of the respective hub. This is not only difficult and cumbersome to carry out but requires manpower. Because of the manpower requirement, it creates fatigue to labourers handling the hub and increases the handling cost. Also it is time consuming to lift and hold the hub in position. As a result, testing time is increased. Besides, in case the crosspin is removed by mistake or breaks due to fatigue, the inner support member will fall down along with the drive shaft and this can lead to accidents. It is also not possible to make precise alignment of the drive shaft with the drive motor shaft and AC motor shaft because of the height of the inner support member and hence the drive shaft being not adjustable.
OBJECTS OF THE INVENTION
An object of the invention is to provide a machine for testing the performance of an AC motor, which machine reduces manpower requirement for coupling the AC motor shaft to the hub at the drive end of the drive shaft and operator fatigue and also reduces time required for carrying out the testing.
Another object of the invention is to provide a machine for testing the performance of an AC motor, which machine is simple in construction and easy and convenient to operate and is operator friendly.

Another object of the invention is to provide a machine for testing the performance of an AC motor, which machine prevents accidents and facilitates precise alignment of the drive shaft with the drive motor shaft and AC motor shaft.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a machine for testing the performance of an AC motor, the machine comprising drive shaft having a driven end and a drive end and a forked portion at each of the driven end and driving end and a mounting flange at each of the driven end and drive end joined to the respective forked portion with a knuckle joint formed with a bolt, the drive shaft further having a hub at each of the driven end and drive end mounted to the respective mounting flange and comprising a central bore, a support structure having an upright support mounted on a base and a platform mounted at the top of the upright support at the centre of the platform, the platform having a tall upright support arm at one end thereof and a short upright support arm at the other end thereof, the distance between the support arms corresponding to the length of the drive shaft from the centre thereof to the hub at the drive end thereof, the drive shaft being mounted on the tall upright support arm at the centre of the drive shaft with the hub at the drive end thereof mounted on the short upright support arm, the drive shaft having at the driven end thereof a drive motor mounted on a mounting block with the drive motor shaft engaged in the respective hub and coupled thereto and the drive shaft having at the drive end thereof the AC motor to be tested mounted on a mounting block with the AC motor shaft engaged in the respective hub and coupled thereto.

The following is a detailed description of the invention with reference to the accompanying drawings, in which :
Fig 1 is an elevation of the machine for testing the performance of an AC motor according to an embodiment of the invention;
Fig 2 is an isometric view of the drive shaft of the machine of Fig 1;
Fig 3 is an isometric view of the support structure of the drive shaft of the machine of Fig 1; and
Fig 4 is a crosssectional view of the upright support of the support structure of Fig 3.
The machine 1 for testing the performance of an AC motor 2 as illustrated in Figs 1 to 4 of the accompanying drawings comprises a support structure 3 having an upright support 4 mounted on a base 5. The upright support comprises an inner support member 6 engaged in an outer support member 7. The upper portion 6a of the inner support member is externally threaded and the lower portion 6b of the inner support member is formed with an oblong groove 6c. The threaded upper portion of the inner support member is in thread engagement with a nut 8 fitted at the upper end of the outer support member (Fig 4). 9 is a grub screw engaged in the oblong groove in the lower portion of the inner support member through a lateral hole 10 in the outer support member. The inner support member is moved up and down in the outer support member by rotating the inner support member in opposite directions within the upper support member after disengaging the grub screw from the oblong groove at

the lower portion of the inner support member. Due to the thread engagement between the upper portion of the inner support member and the nut at the upper end of the outer support member, the inner support member moves up and down in the outer support member on being rotated in opposite directions. The inner support member remains otherwise supported in position because of the thread engagement between the upper portion of the inner support member and the nut. The inner support member is locked in position and prevented from rotating by engaging the grub screw in the oblong groove. 11 is a platform mounted at the top of the inner support member at the centre of the platform. The platform comprises a tall upright support arm 12 at one end thereof and a short upright support arm 13 at the other end thereof. The top surfaces of the upright support arms are formed with recesses 12a and 13a respectively. 14 is a drive shaft (carden shaft) having a driven end 14a and a drive end 14b and a pair of forked portions 14c and 14d at the driven end and drive end thereof, respectively. A pair of mounting flanges 14e and 14f each is provided at each end of the drive shaft. Each of the mounting flanges is joined to each of the forked portions with a knuckle joint formed with a bolt 14g. The drive shaft also comprises a pair of hubs 14h, 14i each mounted to each of the mounting flanges. The hubs each has a central bore 14j therein. The drive shaft is mounted on upright support arm 12 at the centre of the drive shaft. The recess at the top surface of the support arm corresponds to the outer diameter of the drive shaft so as to allow the drive shaft to sit properly at the top surface of support arm 12. The drive shaft has at the driven end thereof a drive motor 15 mounted on a mounting block 16 with the drive motor shaft 17 engaged in the central bore of the respective hub and coupled thereto, for instance, with a key and keyway arrangement (not shown). The other hub of the drive shaft at the drive end thereof is located in the recess 13a at the top surface of the upright support arm 13.

The recess at the top surface of the support arm 13 corresponds to the outer circumference of the other hub to locate the hub properly at the top surface of the upright support arm 13. The distance between the support arms corresponds to the length from the centre of the drive shaft to the hub at the drive end of the drive shaft. The AC motor 2 to be tested is mounted on a mounting block 18 with the AC motor shaft 19 engaged in the respective hub and coupled thereto, for instance with a key and keyway arrangement (not shown). According to the invention the hub at the drive end of the drive shaft always remains supported on the respective support arm and aligned with the drive shaft. When the AC motor is required to be tested, it is mounted on the mounting block 18 at the drive end of the drive shaft and the AC motor shaft is simply engaged in the central bore of the respective hub and coupled thereto. The recesses at the top surfaces of the support arms are aligned such that when the drive shaft and the hub at the drive end of the drive shaft are mounted in the respective recesses at the top surfaces of the support arms, the drive shaft remains coaxial with the drive motor shaft at the driven end side and AC motor shaft at the drive end side. Therefore, manpower requirement to lift the hub and align it with the AC motor shaft and hold the hub in position until the AC motor shaft is engaged in the central bore of the hub and coupled to the hub has been eliminated. Because of the elimination of manpower required for handling the hub, labour cost is eliminated, operator fatigue is eliminated and time required for carrying out the testing is substantially reduced. As the inner support member is always held in position in the nut, there are no possibilities of the inner support member slipping down. Therefore, there are no chances of any accidents happening. It is also possible to carry out precise height adjustment of the drive shaft by moving the inner support member up and down so as to ensure proper alignment of the drive shaft with the drive motor shaft and AC motor

shaft. It is understood that the drive shaft support structure can be of a different configuration and construction. The invention is basically in holding the hub at the drive end of the drive shaft in position aligned with the drive shaft and facilitating precise height adjustment of the drive shaft and preventing the drive shaft from falling down accidentally. Variations in the construction and configuration of the invention for achieving the above objectives are obvious to those skilled in the art and such variations are to be construed and understood to be within the scope of the invention.

We claim:
1) A machine for testing the performance of an AC motor, the machine comprising drive shaft having a driven end and a drive end and a forked portion at each of the driven end and driving end and a mounting flange at each of the driven end and drive end joined to the respective forked portion with a knuckle joint formed with a bolt, the drive shaft further having a hub at each of the driven end and drive end mounted to the respective mounting flange and comprising a central bore, a support structure having an upright support mounted on a base and a platform mounted at the top of the upright support at the centre of the platform, the platform having a tall upright support arm at one end thereof and a short upright support arm at the other end thereof, the distance between the support arms corresponding to the length of the drive shaft from the centre thereof to the hub at the drive end thereof, the drive shaft being mounted on the tall upright support arm at the centre of the drive shaft with the hub at the drive end thereof mounted on the short upright support arm, the drive shaft having at the driven end thereof a drive motor mounted on a mounting block with the drive motor shaft engaged in the respective hub and coupled thereto and the drive shaft having at the drive end thereof the AC motor to be tested mounted on a mounting block with the AC motor shaft engaged in the respective hub and coupled thereto.
2) The machine as claimed in claim 1. wherein the top surface of each of the upright support arms is formed with a recess, the recess at the top surface of the tall support arm corresponding to the outer diameter of the drive shaft and the recess at

the top surface of the short support arm corresponding to the outer circumference of the hub at the drive end of the drive shaft.
3) The machine as claimed in claim 1 or 2, wherein the upright support comprises an inner support member engaged in an outer support member, the upper portion of the inner support member being externally threaded and the lower portion of the inner support member being formed with an oblong groove, the threaded upper portion of the inner support member being in thread engagement with a nut fitted at the upper end of the outer support member and a grub screw engaged in the oblong groove in the lower portion of the inner support member through a lateral hole in the outer support member.