FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Actuating shaft locking arrangement and shaft adjustability of electrical switch
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

Actuating shaft locking arrangement and shaft adjustability of electrical switch Field of the invention
The present invention relates to shaft locking arrangement in electrical devices. More particularly it relates to robust shaft locking arrangement of electrical switches along with indication, length adjustability and NO - NC contacts actuation used for remote indication or signaling purposes.
Background of the invention
Electrical switches are being used in different panel sizes, there is a requirement of different shaft lengths by different customers. It is necessary to lock the shaft as per the length required by the customer and provide a robust locking.
There are many ways to achieve this. Considering the existing practice of locking the shaft, prior art US2008/0247816Al.In this prior art (see Figure 1), there is a protrusion provided in the actuating shaft (3). There is a threaded hole provided in this protrusion. There is a spring steel tightening piece (6) which is held in place with the help of a tightening screw (4). When the screw is tightened, the tightening piece presses against the handle shaft (1) which is passing through the actuating pipe shaft and holds it to the actuating pipe shaft.
This method of shaft locking has a disadvantage since it pushes the shaft against the pipe shaft, and hence has a tendency to tilt the pipe shaft depending on the clearance to its resting face. Also this restricts the movement of the shaft in x-y plane giving it no flexibility while being fitted into the handle which is placed on the panel door - resulting in difficulty for panel door closing even with a slightest mismatch between switch mounting and panel door cut out centers. This mismatch normally occurs as the process involved is fabrication.
Another problem with such an arrangement is that a protrusion is required on a usually cylindrical actuating shaft, making its manufacturing complicated. As a result a corresponding cut has to be provided onto the switch cover for fitment (refer Figure 2). This cut impairs the aesthetics of the switch and ingress protection (IP).
Another method of locking shaft presently is by using bush clip. In this there are two disadvantages- it not only has an undercut in the shaft which weakens the shaft and moreover,

there is no shaft adjustability possible. What is required is robust shaft locking arrangement of electrical switches along with indication, length adjustability and NO - NC contacts actuation used for remote indication or signaling purposes.
Object of the invention:
One object of the present invention is to provide a robust shaft locking arrangement in electrical devices where length of the shaft can be varied for different panel sizes.
Another object of the present invention is to provide locking such that the shaft and shaft pipe is free to move in the x-y plane and not restricted.
Yet another object of the present invention is to provide single system for shaft adjustment with locking and auxiliary actuation and indication.
Further object of the present invention is to improve the aesthetics of the switch by eliminating any protrusion on the shaft locking component visible outside.
Summary of the invention:
The actuating shaft locking arrangement consists of a mechanism plate having a central cavity and plurality of holes for connecting the plate to other structures. A cam indicator which has hollow tubular structure and a pipe shaft mounted in it, is passed through the central cavity on the mechanism plate. The shaft to be locked is passed through the tubular structure of the cam indicator. The cam indicator has semi-circular grooves on its tubular profile for mounting shaft locking clamps. The shaft is inserted in the hollow tubular structure of cam indicator and it is locked using locking clamps. Rotation of the shaft is indicated by a pointer provided on the cam indicator. Onto this plate the auxiliary contact assembly is fixed and the indication rotation of the shaft is shown by the pointer. The cam indicator is connected to gearing arrangement at its bottom through a connector. In order to lock the shaft at desired height, the required length of the shaft is pulled out and clamps are tightened into the grooves provided in the cam indicator.

Description of the Drawings:
Fig. 1 shows side view of shaft locking arrangement in prior art (US2008/0247816A1)
Fig.2 shows actual shaft locking arrangement in Prior art (US2008/0247816A1)
Fig. 3(a) and 3(b) shows shaft and locking arrangement in existing bush clip shaft locking arrangement
Fig.4 shows assembly of shaft locking arrangement in prior art (Bush clip Shaft locking arrangement)
Fig. 5 shows the mechanism with the shaft locking arrangement of the present invention
Fig. 6 shows the exploded view of the shaft locking arrangement with the mechanism
Fig. 7 shows the exploded view of the shaft locking components
Fig. 8 shows the cross section view of the assembly with every component of the shaft locking assembly
Fig. 9,10 shows each and every component involved in the shaft locking arrangement
Fig. 11 shows the actuating cam which turns on the auxiliary contact and helps in locking the shaft also
Fig.12 shows the shaft locking clamps which are used to lock the shaft
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.
List of components:
101- Shaft locking clamp 102-Cam Indicator 103- Screw/Hardware

104-Nylocknut
105- Shaft
106- Mechanism plate
107- Connector
108- Vertical gear
109- Horizontal gear
110- Auxiliary contact assembly
This arrangement allows shaft to be inserted with a pre-determined length for adjustability. At any point within this pre-determined length, the shaft can be tightened or locked. There is a minimum length of shaft that is required to be maintained in the connector to ensure sufficient engagement for positive torque transmission for which a warning mark is provided so that customer does not pull the shaft further. Also, there is provision to accommodate castle lock later if needed (which is being generally offered as an accessory), even when the shaft is having maximum engagement with the connector (viz. minimum shaft length required to be used by the customer).
This shaft locking arrangement is integrated with the auxiliary contacts also. Cam indicator (B) is designed such that it cannot be assembled in wrong orientation (Poka yoke is ensured in design); refer the figure 8, 10 for its assembly. This cam indicator B, is held tightly on to the mechanism by its base (protrusion) being held firmly by the mechanism plate (which is shown in Fig. 6). which is in turn held rigidly to the mechanism by means of hardware. Onto this plate the auxiliary contact assembly is fixed (by means of hardware on the component) with the indication (rotation of the shaft) being shown by the pointer in this cam indicator (B). The shaft is then inserted into the pipe shaft. In order to lock the shaft at desired height, the required length of the shaft is pulled out of the connector and clamps (A) are tightened into the grooves provided in the indicator (B) with the help of the hardware and nylock nuts. The movement of the indicator in the "z" direction is restricted by the mechanism plate. Hence, giving a rigid, simple shaft locking arrangement.

Some of the advantages of the present invention are:
1. This arrangement allows play of shaft in the x-y plane in addition to plane Z thus helping in smooth entry of the shaft into the handle (which is fitted on to the panel door).
2. This helps in avoiding tilting of the pipe shaft in which the shaft is placed thus helping in ideal meshing of the gears which is attached to the pipe shaft.
3. Single system for shaft adjustment with locking and auxiliary actuation and indication

We claim,
1) The actuating shaft locking arrangement for electrical devices comprising;
a mechanism plate, the mechanism plate mounted on the electrical device and the plate
has a circular cavity at its centre,
a cam indicator, the cam indicator having hollow tubular structure with a pointer
projection and semi-circular grooves along its length and the cam indicator is mounted in
the said central cavity of the mechanism plate,
an auxiliary contact assembly mounted over the said cam indicator and mechanism plate,
an actuating shaft, one end of the actuating shaft passing through the said hollow tubular
structure of the cam indicator and
at-least two fixing clamps, the fixing clamps mounted in the said semi-circular grooves
on the cam indicator around the said actuating shaft and fixed together to lock the
actuating shaft.
2) The actuating shaft locking arrangement for electrical devices of the claim 1, wherein, the cam indicator is connected to the said electrical device through gearing arrangement.
3) The actuating shaft locking arrangement for electrical devices of the claim 1, wherein,
to lock the shaft at desired height, the required length of the shaft is pulled out and clamps are tightened into the grooves provided in the cam indicator.
4) The actuating shaft locking arrangement for electrical devices of the claim 1, wherein warning mark is provided on the shaft to maintain minimum length in the connector to ensure sufficient engagement for positive torque transmission.
5) The actuating shaft locking arrangement for electrical devices of the claim 1, wherein base of the cam indicator is held by the tightly between the said mechanism plate and electrical device.
6) The actuating shaft locking arrangement for electrical devices of the claim 1, wherein, the rotation of the actuating shaft is indicated by the pointer.