FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION
"A structurally enhanced knob with a padlock"
2.APPLICANT(S)
(a) NAME: Larsen and Toubro Ltd.
(b) NATIONALITY: Indian
(c) ADDRESS : L&T HOUSE, BALLARD ESTATE, MUMBAI-400 001, INDIA
3. PREAMBLE TO THE DESCRITION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Title
A Structurally Enhanced Knob with a Padlock
Field of the invention
The present invention relates to the field of electrical protection devices, particularly circuit breakers, involving a novel embodiment to trip the breaker manually for purposes of maintenance and checks whenever needed.
Background of the invention
Most switchgear manufacturers provide for a motion hindrance knob; however, most of them constrain the motion by transmitting the load to a non-structural member. This leads to lower abuse-wear sustenance by the knob. Layman users may inflict higher than recommended loads on the knob leading to wear or even irreversible damage to the knob. The device will be rendered useless in most cases without the knob.
What is required is a way to enhance the structural durability and load bearing capacity of the knob using two structural members which lock against each other when actuated by a moving non-structural body and a failsafe method which is suitable to even layman users.
Objects of the invention
One object of the present invention is to provide a knob that distributes all the loads to the structural members alone thus avoiding the breakage of weaker members.
Another object of the invention is to solve the problem of frequent breakages of the operating knob caused due to overload and horse play by inept users.
Summary of the invention
In accordance with the above objects, there is provided a structurally enhanced knob with a padlock for electrical circuit breakers, comprising:
a structural member 3, comprising:
two identical arms 32, each having one or more cavities 321 and a structural member pivot hole 322; and
a flange 31 having a flange hole 312;
a knob cover 1 comprising:

two identical hollow walls 51, each having a knob cover pivot hole 12 for accommodating a pivot pin 6, the knob cover pivot holes 12 matching with structural member pivot holes 322;
an interior cavity 11 formed between the hollow walls;
a knob cover hole 13; and
a step,
each of the identical hollow walls engulfing one of the identical arms of the structural member;
a swivelling member 2 comprising:
a cam 23;
a swivelling member pivot hole 21; and
a swivel handle 22,
the swivelling member being assembled in the interior cavity 11 of the knob cover 1 with the pivot pin 6 passing through the swivelling member pivot hole 21;
a return spring 5; and
a prismatic member 4 having a head 42, a shoulder 41 formed under the head 42, and a shaft 43, the prismatic member being assembled into the knob cover hole 13 with the return spring 5, the return spring 5 resting between the shoulder 41 and the step in the knob cover 1; and the shaft 43 of the prismatic member 4 passing through the flange hole 312,
wherein on rotating the knob the prismatic member 4 is pushed against the structural member 3 without any load being transmitted to the swivelling member 2.
Brief Description of Drawings
Fig. 1 shows OFF condition of the knob. Fig. 2 shows OFF condition of the knob. Fig. 3 shows ON condition of the knob.

Fig. 4 shows ON condition of the knob.
Fig. 5 shows exploded view of the assembly of the knob.
Fig. 6 shows cross sectional view of the assembly of the knob in the ON position.
Fig. 7 shows another view of knob.
Fig. 8 shows knob cover.
Fig. 9 shows Swivelling member.
Fig. 10 shows structural member.
Fig.ll shows prismatic member and return spring.
List of Components

Component No. Name of the Component
1 Knob cover
2 Swivelling member
3 Structural member
4 Prismatic member
5 Return spring
6 Pivot pin
32 Identical arms of structural member
321 Cavities in arms of structural member
322 Structural member pivot hole
31 Flange of structural member
312 Flange hole
51 Identical hollow walls of knob cover
12 Knob cover pivot hole
11 Interior cavity of knob cover

13 Knob cover hole
23 Cam of swivelling member
21 Swivelling member pivot hole
22 Swivel handle
42 Head of prismatic member
41 Shoulder of prismatic member
43 Shaft of prismatic member
Detailed Description
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 following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and the claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a", "an" and "the" include plural referents unless the context clearly indicates otherwise.
By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and

other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
Accordingly, a structurally enhanced knob with a padlock is provided for electrical circuit breakers, which comprises two structural members {structural member 3 and prismatic member 4), an actuating member (swivelling member 2) and a return spring 5. When the actuating member is displaced rotationally, it causes the prismatic member to egress the knob and it can be used for constraining the knob motion. On loading, the actuating member, which is generally the weakest part of the assembly of the knob, fails in typical knobs. The present knob distributes all loads to the structural members alone thus avoiding the breakage of non-structural weaker members.
The invention comprises of a knob made of a knob cover 1, a swivelling member 2, a structural member 3, a prismatic member 4, and a return spring 5.
The knob can have two discrete positions viz. an ON condition as shown in Fig 3 and an OFF condition shown in Fig 1.
Fig. 10 shows the structural member, which comprises two identical arms 32, each having one or more cavities 321 and a structural member pivot hole 322; and a flange 31 having a flange hole 312.
The knob cover 1 has two identical hollow walls 51 as shown in Fig. 5, each having a knob cover pivot hole 12 as shown in Fig. 8 for accommodating a pivot pin 6, the knob cover pivot holes 12 matching with structural member pivot holes 322. Each of the identical hollow walls engulfs one of the identical arms of the structural member.
The knob cover 1 has an interior cavity to accommodate the swivelling member 2. The knob cover also has a hole in for a pivot pin 6, this hole matches with the structural member pivot hole 322. The swivelling member is assembled in this interior cavity along with the pivot pin as shown in Fig. 2.
The prismatic member 4 and the return spring 5 are show in Fig. 11. The prismatic member 4 has a head 42, a shoulder 41 formed under the head 42, and a shaft 43 shaft 43 passing through the flange hole 312. The prismatic member 4 is assembled into the hole 13 in the knob cover 1 with a return spring 5. The return spring rests between the shoulder 41 in the prismatic member and the step in the knob cover. The hole 31 in the flange of the structural member for the prismatic member matches with the knob cover hole 13.
When the swivelling member 2 is pulled out to the OFF condition as shown in Fig.l, the swivel member 2 pivots about the pivot pin 6 and the cam in the swivel member 23 touches the head of the prismatic structural member 42.The displacement of the prismatic member 4 leads to the compression of the return spring 6>as shown in Fig 4.

On mounting a padlock in the knob, the swivel member stays in the OFF position as shown in Fig.l.
On rotating the knob the prismatic member is pushed against the structural member without any load being transmitted to the swivelling member 2.
On releasing the swivelling member 2 the return spring pushes the prismatic member which pushes the swivel member to the ON state. The exposed part of the prismatic member 4 ingresses the knob.

We Claim:
1. A structurally enhanced knob with a padlock for electrical circuit breakers, comprising:
a structural member 3, comprising:
two identical arms 32, each having one or more cavities 321 and a structural member pivot hole 322; and
a flange 31 having a flange hole 312;
a knob cover 1 comprising:
two identical hollow walls 51, each having a knob cover pivot hole 12 for accommodating a pivot pin 6, the knob cover pivot holes 12 matching with structural member pivot holes 322;
an interior cavity 11 formed between the hollow walls;
a knob cover hole 13; and
a step,
each of the identical hollow walls engulfing one of the identical arms of the structural member;
a swivelling member 2 comprising:
a cam 23;
a swivelling member pivot hole 21; and
a swivel handle 22,
the swivelling member being assembled in the interior cavity 11 of the knob cover 1 with the pivot pin 6 passing through the swivelling member pivot hole 21;
a return spring 5; and
a prismatic member 4 having a head 42, a shoulder 41 formed under the head 42, and a shaft 43, the prismatic member being assembled into the knob cover

hole 13 with the return spring 5, the return spring 5 resting between the shoulder 41 and the step in the knob cover 1; and the shaft 43 of the prismatic member 4 passing through the flange hole 312,
wherein on rotating the knob the prismatic member 4 is pushed against the structural member 3 without any load being transmitted to the swivelling member 2.
2. The knob of Claim 1 wherein the knob can have two discrete positions viz. an ON position when the swivelling member 2 is not pulled out and an OFF position when the swivelling member 2 is pulled out with the swivel handle 22.
3. The knob of Claim 2 wherein in the OFF position the swivelling member 2 pivots about the pivot pin 6 and the cam 23 in the swivel member 2 touches the head 42 of the prismatic member 4, displacing the prismatic member 4 by compressing the return spring 5 and exposing a part thereof as the prismatic member egresses the knob, and the swivelling member 2 stays so in the OFF position upon mounting a padlock in the knob; and, on releasing the swivelling member 2 the return spring 5 pushes the prismatic member 4 which pushes the swivelling member 2 to the ON state, when the exposed part of the prismatic member 4 ingresses the knob.