FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Cam Operated Rotary Mechanism
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
4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -"I/We claim" on separate page)
6. DATE AND SIGNATURE (to be given on the last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on the
separate page)
Note:
*Repeat boxes in case of more than one entry
*To be signed by the applicant(s)or the authorized registered patent agent
*Name of the applicant should be given in full, family name in the beginning
*Complete address of the applicant should be given stating with postal index no. / code, state and
country
*Strike out the column which is/are not applicable

Field of the Invention:
The present invention relates to the field of low-voltage switching devices in an electrical circuit. This invention pertains to a cam-operated rotary mechanism, employable in low-voltage switchgear devices for efficient operation.
Background of the Invention:
Switching devices are instruments employed for opening and closing an electric circuit. The switching device comprises at least one pole and a mechanism control device adapted to open and close said pole. Switching devices include switches and switch-fuses.
US2008/0035464 Al discloses a switching device which includes a working shaft and a control shaft installed in a frame part, the control shaft being rotatable and adapted to turn the working shaft, and the working shaft being adapted to change the position of poles of the switching device. One of the two shafts passes through the other. The transmission from the control shaft to working shaft is through a cam element which actuates the peg of the working shaft.
The problem in the said arrangement is that the system becomes inefficient in multiple transmissions i.e. from control shaft to cam element, cam element to working shaft and working shaft to poles of switching device.
US005934455A discusses the use of a double torque exerting mechanism that provides accurate positioning in ON and OFF positions for linearly sliding contacts.
The above disclosed prior art suffers from the following drawbacks of not being suitable for a rotary contact system. The disclosed arrangement is non-modular thus having difficulty in assembly. In said invention there is no provision for side operation.
Thus, there is a need to overcome the problems of the prior art. Hence the present invention describes a cam-operated rotary toggling mechanism for use in low voltage switchgear, which would reduce number of components and have a simpler construction to increase the performance of the mechanism. The present invention can be used for single switching as well as for multi switching operation.

Objects of the Invention:
Accordingly with a view to eliminate the above mentioned draw-backs, the main object of the present invention is to provide multiple stable switch positions by using single pair of cam-follower arrangement and thereby reduce the space of the entire mechanism making it modular.
Another object of the present invention is using a common actuating member for the two switching operations thus eliminating the possibility of the two switches remaining ON simultaneously when used as a change-over switch.
Nevertheless another aim of the current invention is the use of a single moving contact assembly for multiple switch positions.
A further object of the present invention is to use a common left and right housing thus reducing investment cost.
Yet another object of the invention is reduction in the number of varieties, thus reducing the number of components used and lowering the manufacturing cost.
Summary of the Invention:
The aim of the present invention is achieved by using a horizontal rotor actuated cam-follower assembly which guides the follower and spring arrangement through the guiding slot in the common mechanism housing thereby compressing the mechanism spring. On release of this compressed spring the moving contact toggles from its initial position thus making or breaking its contact with the terminals. This motion of the rotor assembly being actuated by the manual actuating shaft finally moves the follower arrangement to establish the toggling operation of the contact system.
Brief Description of the drawings:
Figure 1 shows the prior art corresponding to US2008/0035464 Al.
Figure 2 shows the prior art corresponding to US005934455A.
Figure 3 shows the view of modular switch, having modular rotary mechanism assembled to the extreme left.

Figure 4 shows the view of modular switch, having modular rotary mechanism connected at the centre.
Figure 5 shows the isolated modular rotary mechanism with 6 spikes.
Figure 6 shows the exploded view of modular rotary mechanism with 6 spikes.
Figure 7 shows the cross-sectional view of modular rotary mechanism with 6 spikes in OFF Position.
Figure 8 shows the cross-sectional view of modular contact system in OFF Position.
Figure 9 shows the cross-sectional view of modular rotary mechanism with 6 spikes in Dead-Centre Position.
Figure 10 shows the cross-sectional view of modular rotary mechanism with 6 spikes in ON-I Position.
Figure 11 shows the cross-sectional view of modular contact system in ON-I Position.
Figure 12 shows the cross-sectional view of modular rotary mechanism with 6 spikes in ON-II Position.
Figure 13 shows the cross-sectional view of modular contact system in ON-II Position.
Figure 14 shows the cross-sectional view of modular rotary mechanism with 4 spikes in OFF Position.
Figure 15 shows isolated horizontal rotor with 6 spikes.
Figure 16 shows the cross-sectional view of horizontal rotor with 6 spikes.
Figure 17 shows isolated horizontal rotor with 4 spikes.
Figure 18 shows the cross-sectional view of horizontal rotor with 4 spikes
Figure 19 shows the isolated follower.
Figure 20 shows the isolated vertical rotor.

Detailed Description:
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.
According to a preferred embodiment of the invention, there is provided a simple switch, which is consisting of contact system (13) and rotary mechanism (14). Furthermore the contact system (13) is a rotary-butt type contact system having multi pole construction and the mechanism (14) . is a multi-cam operated mechanism (Figure 1).
Accordingly, in the present invention disclosed hereinafter, there is provided a rotary mechanism for use in simple switch and transfer switches. The mechanism is supported on the common mechanism housing (4). The actuating shaft (2) is coupled to the vertical rotor (3). By this coupled actuating shaft (2) and vertical rotor (3) the mechanism is driven and this combined shaft (2) and vertical rotor (3) is located in the common mechanism housing (4). The vertical rotor (3) is coupled to the horizontal rotor (5a) with the help of a multi-toothed cam and both rotors rotate in planes perpendicular to each other. The horizontal rotor (5a) rotates in the common mechanism housing (4) and which is coupled to the other pole of the contact system (13) from either side.
The horizontal rotor (5a) is the critical component in the mechanism. The horizontal rotor (5a) is driven by vertical rotor (3) and which is going to drive the contact system (13) from either side. There is a multi-cam profile provided, in order to drive the follower (7). Due to this multi-cam profile, multiple switching operations can be performed. This multi-cam profile together with the horizontal rotor (5a) and follower (7), helps to achieve toggling operation; i.e., when we operate

the vertical rotor, which will drive the horizontal rotor, at this instant, the follower (7) slides along the cam and at dead centre it reaches exactly edge of multi-cam over there due to sharp edges in both components, which toggle quickly and achieves quick make operation. Similarly a quick break operation can also be achieved. This type of mechanism can be called 'multi cam toggling mechanism' or 'quick-make & quick break mechanism'.
The Cam with 4 spikes can be used for simple switch (i.e., Switch Disconnector) having only two positions (ON & OFF), Similarly, the Cam with 6 spikes can be used for on-load transfer switch (i.e., Changeover Switch Disconnector) having three positions (ON-I, OFF, ON-II).
In this mechanism, the mechanism springs (6) are resting on Followers (7), and which are thus indirectly connected to the horizontal rotor (5a). The other end of the mechanism spring (6) rests on the mechanism housing (4). This Follower (7) will act as spring guide and which is guided in the mechanism housing (4). The Followers (7) are free to move through the slot provided on the mechanism housing (4), but the mechanism springs are not. The Left and Right common mechanism housings are held together by means screw fitment.
According to a preferred embodiment of the invention, there is provided a contact system for use in simple switch and transfer switches. The contact system parts are supported on the common contact system housing (8) which consists Terminal 1 (10), Terminal2 (11), Rotor (9), Compression Spring and Moving contact (12). The moving contact is held in the rotor with the help of compression springs, which will provide contact pressure in ON-condition. The rotor assembly, Terminal 1 and Terminal2 are located in the housing.
The Exploded view of the toggling mechanism (Figure 6) consists of an Actuating Shaft, Groove Pin, Vertical Rotor, Horizontal Rotor, Follower, Springs and Mechanism Housing.
The switch is considered to be initially in the OFF position (Figure 8), a position where the toggle mechanism assumes a peculiar shape (Figure 7). The vertical rotor may be driven by the operator with the help of the handle shaft rotating through an angle a. The vertical rotor then drives the horizontal rotor which rotates through an angle p. a is not necessarily equal to p. In case of switch in ON state-I, the horizontal rotor (5a) has to rotate the follower, and the follower begins to compress the mechanism springs. Human effort is required to take the toggle mechanism from OFF to dead centre (Figure 9). It is in this position that the mechanism springs

are fully compressed. At this instant the Contact System is still in OFF state only (Figure 8). from here on, the mechanism springs release the stored energy to take the toggle mechanism to ON state (Figure 10). At this instant the Contact System shown is in ON-I state (as shown in Figure 11)
In case the switch is in ON state-I, the horizontal rotor (5a) rotates and thereby moves the follower, the follower begins to compress the mechanism springs. Human effort is required to take the toggle mechanism from ON to dead centre (Figure 9). It is in this position that the mechanism springs are fully compressed. At this instant the Contact System is still in ON state only (Figure 11), from here on, the mechanism springs release the stored energy to take the toggle mechanism to OFF state (Figure 7). At this instant the Contact System shown is in OFF state (Figure 8).
When the horizontal rotor (5a) rotates further, the follower begins to compress the mechanism springs. Human effort is required to take the toggle mechanism from OFF to dead centre (Figure 9). It is in this position that the mechanism springs are fully compressed. At this instant the Contact System still in OFF position only (as shown in Figure 8), from here on, the mechanism springs release the stored energy to take the toggle mechanism to ON state (Figure 12). At this instant the Contact System shown in ON-II state (Figure 13).
The toggle mechanism functions with the help of the novel cam and follower concept (Figure 7, 9, 10, 12). Unlike the prior art wherein the spring rests on spring arm or spring guide that is pivoted at both ends, the follower is guided in housing and actuated by horizontal rotor (5a). This allows for less restriction on its degrees of freedom and a better chance for it to compress freely. The toggling of the follower is entirely depends on the profile of the cam. Any slight imbalance of forces will result in the toggling of the follower which ultimately results in the toggling of mechanism.
Stacking of the mechanism common housings are done with the help of stacking screws.

We claim,
1. A cam operated rotary mechanism for switching device comprising;
a housing, the housing having a rounded hole through its centre, and the said housing having a guiding slot along its length on the inner walls;
an actuating shaft passing through said hole in the housing; the actuating shaft having a vertical rotor connected at its end;
a horizontal rotor having a multi-cam profile with a plurality of spikes, and the horizontal rotor connected to the said vertical rotor by a multi-toothed cam in a plane perpendicular to the plane of the vertical rotor;
at least two followers, the followers having arrow shaped profile where the tip of the follower is engaged with the said horizontal rotor through the multi-toothed cam profile; and the other end of the said follower is guided to move freely through the said guiding slot of the housing and providing springs around the said followers at one end to restrict movement of followers;
a contact system housing mounted adjacent to the rotary mechanism housing; the contact system being co-axial with the said horizontal rotor wherein, during toggling of the moving contact from one state to another, the manually operated actuating shaft drives the vertical rotor, the horizontal rotor connected to the vertical rotor moves the follower along the guiding slot in the housing thus compressing the mechanism springs and in next toggling operation, the contact springs are released.
2. A switching device of the claim 1 wherein, the moving contact toggles between an ONI to ON2 through an OFF state.
3. A switching device of the claim 1 wherein, the device can be used for both simple switching operations and also for on-load transfer switching operations.

4. A switching device of the claim 1, as herein above described and illustrated in any of the accompanying drawings.