FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Adjustable Charging Handle Assembly for Circuit Breakers"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. O. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be
performed.

Adjustable Charging Handle Assembly for Circuit Breakers
Field of the invention
The present invention relates generally to circuit breakers, and more particularly, to the circuit breakers, having an adjustable handle assembly to charge the circuit breaker with variable transmission shaft dimensions.
Background of the invention
Circuit breakers provide protection for electrical systems from electrical fault
conditions. Typically, the circuit breakers include an operating mechanism, which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions as detected, for example, by a trip unit. The electrical contact assemblies include stationary electrical contacts and corresponding movable electrical contacts that are separable from the stationary electrical contacts.
Among other components, the operating mechanisms of the circuit breakers
typically include a pole shaft, a trip actuator assembly, a closing assembly and
an opening assembly. The trip actuator assembly responds to the trip unit and
actuates the operating mechanism. The closing assembly and the opening
assembly may have some common elements, which are structured to move the movable electrical contacts between a first, open position, wherein the movable and stationary electrical contacts are separated, and a second, closed position, wherein the movable and stationary electrical contacts are electrically connected. Specifically, the movable electrical contacts are coupled to the pole shaft. Elements of both the closing assembly and the opening assembly, which are also pivotably coupled to the pole shaft, pivot the pole shaft in order to effectuate the closing and opening of the electrical contacts. The force required to close the electrical contacts the circuit breakers is greater than what a human

can typically provide. For this and other reasons, the circuit breakers include at least one stored energy mechanism such as springs, to facilitate the closing process. Specifically, the circuit breaker operating mechanism permits the circuit breaker to store the energy by compressing springs that are linked to the contact assembly of the circuit breaker by latching different links. The stored energy of the springs and latching between the linkages allows circuit breaker to make the contacts, hence completing the electrical circuit (closing of breaker) and break the contacts, hence interrupting the electrical circuit (tripping of breaker).
Further, the closing spring(s) can be charged either automatically, for example, using an electric motor, or manually, for example, by operating a charging handle that is accessible from the exterior of the circuit breaker housing for this purpose. The charging handle is part of a charging assembly for charging the closing spring(s). During the manual charging operation, the possibility exists that the charging handle could be unintentionally released (e.g., without limitation, accidently dropped). Under such circumstances, depending on the position of the charging handle, energy that has already been stored (e.g., closing spring(s) partially charged) could be suddenly released, causing damage to one or more components of the closing assembly and/or charging assembly.
Generally, the circuit breaker manufacturers provide a loaded ratchet and pawl assembly in charging system for latching. During each stroke, due to play between the ratchet and the pawl assembly and clearances between kinematic pairs, there is always a chance of back thrust coming while charging at the customer interface. This leads to more wear and tear of assembly which reduces the mechanical life of mechanism.
Further, the manufacturers provide a system which allows one-directional motion output, however it is restricted to be used in specific mechanism, with fixed shaft and bearing sizes only, with no scope of interchangeability.

Accordingly, there exists a need to provide charging handle assembly for circuit breakers which overcomes drawbacks of the prior art.
Objects of the invention
An object of invention is to reduce back thrust coming while using charging handle assembly for circuit breakers at the customer interface.
Another object of the present invention is to provide interchangeable charging handle assembly for different frames of the circuit breakers with differential transmission ratios.
Summary of the invention
Accordingly, the present invention provides an adjustable charging handle assembly for circuit breakers having movable electrical contacts coupled to a shaft. The adjustable charging handle assembly comprises a bearing holder assembly capable of being connected to a mechanism side plate (35). The bearing holder assembly includes a bearing holder, and a bearing member housed in the bearing holder unidirectionally. The bearing member is capable of being seated on the shaft. Further, the bearing holder assembly includes at least two mounting plates capable of holding the bearing member within the bearing holder and at least two self adjusting screw member configured within the bearing holder for pressing the mounting plates to hold the bearing member therein. Furthermore, the bearing holder assembly includes a plurality of toothed profile members attached to the bearing holder.
The adjustable charging handle assembly further comprises a handle assembly capable of communicating with the bearing holder assembly. The handle assembly includes a handle body member, and a pawl pivoted on the handle

body member. The pawl is capable of being rested on any of the plurality of toothed profile members. Wherein, for a given size of the bearing member and the shaft, the bearing holder assembly adjusts itself and mounts the bearing member on the shaft and the plurality of toothed profile members along with the pawl provides for differential transmission ratios during each stroke of charging thereby achieving an unidirectional motion transmission with adjustable motion transmission ratio in each stroke of charging.
Brief description of the drawings
Figure 1 shows an assembled view of an adjustable charging handle assembly for circuit breakers, in accordance with the present invention;
Figure 2 shows a perspective view of a bearing holder assembly of the adjustable charging handle assembly of figure 1;
Figure 3 shows a cross-sectional view of the bearing holder assembly of figure
2;
Figure 4 shows perspective view of a handle assembly of the adjustable charging handle assembly of figure 1;
Figure 5 shows a plurality of toothed profile members on the bearing holder assembly meshing with a pawl of the handle assembly;
Figure 6 shows a mechanism to adjust the pawl position with reference to the tooth profile, in accordance with the present invention; and
Figure 7 shows an assembled view of an adjustable charging handle assembly on mechanism side plate, in accordance with the present invention.

Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The present invention provides an adjustable charging handle assembly for circuit breakers. The adjustable charging handle assembly reduces back thrust coming while charging handle assembly at the customer interface. Further, the adjustable charging handle assembly provides interchangeable handle assembly for different frames of air circuit breaker with differential transmission ratios.
Referring now to figure 1 to 5, there are shown various view of an adjustable charging handle assembly for circuit breakers in accordance with the present invention. The circuit breakers (not shown) include movable electrical contacts coupled to a shaft. Specifically, elements of a closing assembly and an opening assembly of the circuit breaker, which are also pivotably coupled to the shaft, pivot the shaft in order to effectuate the closing and opening of the electrical contacts.
Figure 1 shows an assembled view of the adjustable charging handle assembly (100) (hereinafter "the charging handle assembly (100)"), in accordance with the present invention. The charging handle assembly (100) includes a bearing holder assembly (50) and a handle assembly (70).
The bearing holder assembly (50) is capable of being connected to a circuit breaker operating mechanism on its side plate (35) shown in figure 7. The bearing holder assembly (50) includes a bearing holder (10), a bearing member (15), at least two mounting plates (20a, 20b), at least two self adjusting screw members (25a, 25b) and a plurality of toothed profile members (30a, 30b, 30c).

Specifically, figure 2 shows perspective view of a bearing holder assembly (50) and figure 3 shows a cross-sectional view of the bearing holder assembly (50).
The bearing holder (10) includes the bearing member (15) housed unidirectionally therein. The bearing member (15) is capable of being seated on the shaft. In an embodiment, the bearing member (15) is seated on the shaft by fixing the bearing holder assembly (50) to the mechanism side plate (35) with the help of at least two mounting screws (45).
The bearing member (15) is held in position within the bearing holder (10) with the help of at least two mounting plates, for example, the mounting plates (20a) and (20b). However, it may be evident to those skilled in the art that more number of mounting plates may be used to hold the bearing member (15). The bearing member (15) is held within the mounting plates (20a, 20b) by means of at least two self adjusting screw members (25a, 25b). The two self adjusting screw members (25a, 25b) decides the position of two mounting plates (20a, 20b).The two self adjusting screw members (25a, 25b) are mounted on the bearing holder (10) such that they pass through the outer covering of the bearing holder (10) and press the mounting plates (20) thereby holding the bearing member (15) firmly therein.
The bearing holder assembly (50) includes the plurality of toothed profile members (30) attached to the bearing member (15). For the purpose of explanation, three toothed profiled members (30a, 30b and 30c) are shown in figure 2. The toothed profiled members (30a, 30b and 30c) are mounted along the end of the bearing holder (10) with the bearing member (15) such that the toothed profiled members (30a, 30b and 30c) are placed one after other. Any one toothed profile member of the toothed profiled members (30a, 30b and 30c) gets engaged with the handle assembly (70) at given point of time.

The handle assembly (70) includes a handle body member (55) and a pawl (60) as shown in figure 4. The pawl (60) is pivoted on the handle body member (55). Specifically, the pawl (60) is pivoted on the handle body member (55) by a screw (62).
The pawl (60) is capable of being rested on any of the plurality of toothed profile members (30a, 30b and 30c) at given point of time. The position of the pawl (60) is adjusted with respect to the shaft's axis by fixing the screw (62) on a slot (65) provided in handle body member (55) using nuts (not shown). Specifically, for specific pawl (60) and a toothed profile member combination, the pawl (60) is moved along the screw (62) axis and rested on any of the toothed profile members (30a, 30b and 30c) as shown in figure 5 and 6.
For a given size of bearing member (15) and shaft, the bearing holder assembly (50) adjusts itself and mounts the bearing member (15) on the shaft. Specifically, the handle assembly (70) is adjusted to have specific toothed profile member (30) and the pawl (60) combination for differential transmission ratios during each stroke of charging. With this combination of the bearing holder assembly (50) and handle assembly (70), a unidirectional motion transmission is achieved with adjustable motion transmission ratio in each stroke of charging.
In the charging handle assembly (100), loading is distributed by the bearing member (15) and handle assembly (70). Further, with adjustment provided in the charging handle assembly (100), both interchangeability and modularity is achieved
Advantages of the invention
1. The charging handle assembly (100) is capable of accommodating different bearing member (15) sizes in the bearing holder (10).

2. The charging handle assembly (100) has a unidirectional motion transfer.
3. The charging handle assembly (100) provides failsafe against abuse loads and back thrust.
4. The charging handle assembly (100) provides interchange-ability and
modularity to be achieved with different bearing members and shaft sizes.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We Claim
1. An adjustable charging handle assembly for circuit breakers
having movable electrical contacts coupled to a shaft, the adjustable charging
handle assembly comprising:
a bearing holder assembly capable of being connected to a mechanism side plate, the bearing holder assembly having,
a bearing holder,
a bearing member housed in the bearing holder unidirectionally, the bearing member being capable of seated on the shaft,
at least two mounting plates capable of holding the bearing member within the bearing holder,
at least two self adjusting screw member configured within the bearing holder for pressing the mounting plates to hold the bearing member therein, and
a plurality of toothed profile members attached to the bearing holder; and
a handle assembly capable of communicating with the bearing holder assembly, the handle assembly having,
a handle body member,
a pawl pivoted on the handle body member, the pawl capable of being rested on any of the plurality of toothed profile members,
wherein, for a given size of the bearing member and the shaft, the bearing holder assembly adjusts itself and mounts the bearing member on the shaft and the plurality of toothed profile members along with the pawl provides for differential transmission ratios during each stroke of charging thereby achieving an unidirectional motion transmission with adjustable motion transmission ratio in each stroke of charging.
2. The adjustable charging handle assembly as claimed in claim 1,
wherein the bearing member is seated on the shaft by fixing the bearing holder

assembly to the mechanism side plate with the help of at least two mounting screws.
3. The adjustable charging handle assembly as claimed in claim 1, wherein the pawl is pivoted on the body member by a screw.
4. The adjustable charging handle assembly as claimed in claim 1, wherein the position of the pawl is adjusted with respect to the shaft's axis by fixing the screw on a slot provided in handle body member using nuts.