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
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An external rotatable ring for neutral setting of a dc motor
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Khatua Satya Ranjan and Pangal Sarvesh, Crompton Greaves Limited, M7 Division, D5 Industrial Area, Mandideep, 462046, Madhya Pradesh, India, both Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention:

Field of Invention
The invention relates to an external rotatable ring for neutral setting of a dc electric motor.
Background
To ensure smooth operation of a dc electric motor, the neutral point of the motor often need to be set. The neutral setting is done either during static conditions or during the operation of the motor by rotating the brush gear and rocker assembly of the motor. The brush gear and rocker assembly are usually accessed by opening the outer case of the motor. However, handling the motor components by opening the motor case is laborious, time consuming and is not safe. It is desirable to achieve the neutral setting of the dc motor externally.
Detailed description
Accordingly, the invention provides an external rotatable ring for neutral setting of a dc electric motor.
In one embodiment, the invention provides an external rotatable ring spaced apart from outer case of the motor, the ring having bolts engaged in holes located on outer surface of the ring, the bolts running through slotted holes on the outer case of the motor and


fastened to the brush and rocker assembly of the motor, the neutral setting being done in static or operating conditions by rotating the ring over the slotted hole.
In another embodiment, the invention provides a method for neutral setting of a dc electric motor, the method comprising rotating an external rotatable ring spaced apart from the outer case of the motor, the ring having bolts engaged in holes located on outer surface of the ring, the bolts running through slotted holes on the outer case of the motor and fastened to the brush and rocker assembly of the motor, the neutral setting being done in static or operating conditions by rotating the ring over the slotted hole
The invention provides a convenient external control for neutral setting of the dc motor. The external ring of the invention is spaced apart from the outer case of the motor to enable free rotation. The neutral setting is achieved by rotating brush and rocker assembly in clockwise or counter clock wise direction externally by rotating the ring in the respective direction over the slotted hole on the outer case of the motor. Therefore, the inconvenience of achieving the neutral setting by opening the motor is avoided. The external ring also provides faster setting of the neutral point as well as provides enhanced safety during operation.
Dated this 31st day of March 2008