FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)
1. Title of the invention
A COUPLING MECHANISM
2. Applicants)
Name Nationality Address
EXCEL CONTROLJNKAGE PVT. LTD. INDIA W-6S .MIDC INDUSTRIAL AREA. HINGNA ROAD.
NAGPUR-440016
3. Preamble to the description
COMPLETE SPECIFIC A TION
The following specification particularly describes the invention and the manner in which it is
to be performed.

The disclosure relates to a non-reaction coupling system. In particular, the disclosure relates to a non-reaction coupling system that prevents forces to be transmitted from the actuated member to the actuating member.
BACKGROUND
Coupling systems are required in many industries including industrial, construction, marine, and mining for various applications. In many such applications it is desired that forces from the actuated member are not transmitted back to the actuating member, while permitting forces to be transmitted from the actuating member to the actuated member.
For example, in existing steering systems, particularly with respect to boats utilizing a steering wheel and a rudder, forces such as propeller torque and rudder force are transmitted back to the steering wheel, thereby causing an increase in steering effort on the part of an operator. These forces acting on the steering wheel are characterized as 'feedback'.
Various techniques have come under consideration for reducing or eliminating 'feedback' and the resistance required by the operator to overcome forces like propeller torque and rudder forces. Some techniques such as worm gear, rack and pinion type and others are put into use as steering control mechanism for boats to reduce or eliminate 'feedback' and the resistance required by the operator to overcome these forces. For example, a worm gear is incorporated in the steering control between the steering wheel and the steering cable so that the propeller torque and rudder forces applied to the boat will not be applied to the steering wheel. The worm gear also locks the boat in the steering position established by the rudder. However, such techniques tend to be more complex and more expensive than the conventional rack and pinion gearing used in steering controls. In another modern approach, power steering may be employed in the steering control to reduce operator steering effort. Power steering may increase the cost of the steering control even more.

In another technique, a clutch mechanism is directly integrated between the steering wheel and the rudder to prevent the propeller torque and rudder forces from acting on the steering wheel. However, this technique also tends to be complex in nature and is difficult to install.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
Figure I is an isometric view of a coupling mechanism in accordance with a first embodiment of the invention.
Figure 2 is a sectional view of a coupling mechanism in accordance with a first embodiment of the invention.
Figure 3 is an isometric view of a coupling mechanism in accordance with a second embodiment of the invention.
Figure 4 is a sectional view of a coupling mechanism in accordance with a second embodiment of the invention.
Figure 5 is an isometric view of a coupling mechanism in accordance with a third embodiment of the invention.
Figure 6 is a sectional view of a coupling mechanism in accordance with a third embodiment of the invention.
Figure 7 is an isometric view of a coupling mechanism in accordance with a fourth embodiment of the invention.
Figure 8 is a sectional view of a coupling mechanism in accordance with a fourth embodiment of the invention.

Figure 9 is a sectional view of a coupling mechanism of the fourth embodiment illustrating the degrees of rotation required and the associated tolerances.
SUMMARY
A non-reaction coupling mechanism for coupling an actuating member to a driven shaft
is disclosed. The non-reaction coupling mechanism comprises of a housing defining an
opening to receive the driven shaft and a cam defining a radial projection positioned within
the housing and mounted on the driven shaft. The radial projection comprises of a central
surface, a first side surface and a second side surface on either side of the central surface such
that the central surface defines a central clearance between the cam and the housing. The first
side surface and the second side surface define side clearances between the cam and the
housing and the side clearances is smaller than the central clearance. The non-reaction
coupling mechanism further comprises of a first roller and a second roller that is positioned
between the radial projection and the housing and having a resilient member in between. The
resilient member is configured to position the first roller at least partly on the first side
surface and the second roller at least partly on the second side surface. The first and second
rollers is sized such that when partly or completely positioned on the side surface the rollers
contact the housing and serve as a wedge between the cam and the housing and when
positioned on the central surface a gap is formed between the rollers and the housing. The
non-reaction coupling mechanism further comprises of a first actuating pin and a second
actuating pin mounted on the actuating member. The first actuating pin and a second
actuating pin are configured to be received within the housing with the first actuating pin
positioned between the cam and the first roller and the second actuating pin positioned
between the cam and the second roller such that rotation of the actuating member causes one

of the actuating pins to push the respective roller from the side surface towards the central surface against the resilient member.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof. Throughout the patent specification, a convention employed is that in the appended drawings, like numerals denote like components.
Reference throughout this specification to "one embodiment" "an embodiment" OT similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in one embodiment", "in an embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
A coupling mechanism for a steering system is disclosed. The coupling mechanism connects the steering member to the steered member such that steering forces from the steering member are transmitted to the steered member but forces from the steered member are not transmitted to the steering member.

Figure 1 illustrates the coupling mechanism in accordance with a first embodiment. The coupling mechanism 100 includes an actuating plate 102 that has plurality of actuating pins 104 projecting from it. Preferably, pairs of actuating pins 104 are mounted on the actuating plate 102 and in the embodiment illustrated, one pair or two actuating pins 104 project from the actuating plate 102. The actuating plate 102 is connected to the throttle lever 200 such that movement of the throttle lever 200 results in movement of the actuating plate 102.
The coupling mechanism further includes a housing 106 with a back surface 108 defining a hollow chamber 110 with internal walls 112. The actuating plate 102 when positioned over the housing 106 forms the front surface (not shown) of the housing 106 with the actuating pins 104 extending into the hollow chamber 110. The housing 106 is preferably tubular defining a circular chamber 110 with an inner wall 112 along its inner circumference. The housing 106 further defines an opening 114 on the back surface 108 in which is mounted a driven shaft 116. A cam 118 is placed within the chamber 110 and is mounted on the driven shaft 116, such that rotation of the cam 118 results in rotation of the driven shaft 116. The cam 118 includes a central opening 120 sized proportionate the driven shaft 116, The cam 118 may be mounted on the driven shaft 116 by way of a keyway, splines or glue. In the embodiment illustrated, the cam 118 is mounted on the driven shaft 116 by splines 122 manufactured in the central opening 120 of the cam 118 and corresponding splines 122 on the external surface of the driven shaft 116.
Referring next to Figure 2, the cam 118 is sized such that it extends across the chamber 128 at one portion while defining at least one cavity 124 between the inner wall 112 of the chamber 110 and the cam 118 at another portion. The cam 118 includes a projection 126 extending in to the cavity 124 towards the inner wall 112 of the housing 106. The projection 126 defines a central surface and a pair of side surfaces abutting the central surface, such that

the pair of side surfaces and the central surface together defines a continuous surface on which a roller 130 may roll. The clearance between the central surface and the inner wall 112 of the chamber 110 is greater than the clearance between the side surfaces and the inner walls 112 of the chamber 110. In the embodiment illustrated, the clearance between both side surfaces and the inner walls 112 of the chamber 110 is the same. On either side of the projection 126 a sub cavity 132 is formed that is sized to receive the actuating pin 104 of the actuating plate 102.
A pair of rollers 130, 136 is placed on the projection 126 between the projection 126 and the inner wall 112 of the chamber 110, with each roller 130, 136 positioned at least partly on a side surface. A spring 134 is placed between the rollers 130, 136. The spring 134 is biased such that it pushes the rollers 130, 136 towards the edge of the side surfaces away from the central surface. The rollers 130, 136 are sized such that when completely or partly on the side surface they contact both the housing 106 and the cam 118 and function as a wedge, whereas when positioned on the central surface a clearance is created between the roller 130, 136 and the housing 106 or the roller 130, 136 and the cam 118. At rest, the rollers 130, 136 serve as a wedge and prevent rotation of the cam 118 within the chamber 110. On assembly, the actuating pins 104 are received within the sub cavities 132 on either side of the projection 126 and may or may not be in contact with the rollers 130, 136.
Rotation of the actuating plate 102 in either direction causes an actuating pin 104 to press against the corresponding roller 130, 136, pushing the roller 130, 136 against the spring towards the central surface. When the roller 130, 136 is pushed on to the central surface, it ceases to function as a wedge and the cam 118 is permitted to rotate. Rotation of the cam 118 causes the driven shaft 116 to rotate and thus rotation of the actuating plate 102 is transmitted to the driven shaft 116. On the other hand, rotating the driven shaft 116 in any direction,

attempting to rotate the cam 118, causes a roller 130, 136 to further move away from the central surface and gets wedged between the cam 118 and the inner wall 112 of the chamber 110. As a result, rotation of the cam 118 is prevented, and consequently rotation of the actuation plate is prevented.
With reference to Figures 3 and 4, a coupling mechanism in accordance with a second embodiment is illustrated. The cam 118 includes at least one pin 138 projecting towards the actuating plate 102. In the embodiment illustrated, a pair of pins 138, 142 is provided on the cam 118 that project towards the actuating plate 102. The actuating plate 102 is provided with corresponding openings 140 formed thereon that receive the pins 138. 142, The openings 140 on the actuating plate 102 are sized larger than the pins 138, 142, such that on assembly a clearance is created between the pins 138, 142 and the edges of the opening.
Rotation of the actuating plate 102 in either direction causes an actuating pin 104 to press against the corresponding roller 130, 136, pushing the roller 130, 136 against the spring 134 towards the central surface. When the roller 130, 136 is pushed on to the central surface, it ceases to function as a wedge and the cam 118 is permitted to rotate. Simultaneously, rotation of the actuating plate 102 to move the roller 130, 136 on to the central surface causes the opening of the actuating plate 102 to engage the pin 138, 142, also causing the cam 118 to rotate. Rotation of the cam 118 causes the driven shaft 116 to rotate and thus rotation of the actuating plate 102 is transmitted to the driven shaft 116. Thus rotation of the actuating plate 102 is transmitted to the cam 118 by both the rollers 130. 136 as well as the dowel pins 138, 142.
On the other hand, rotating the driven shaft 116 in any direction, attempting to rotate the cam 118, causes a roller 130, 136 to further move away from the central surface and gets wedged between the cam 118 and the inner wall 112 of the chamber 110. As a result, rotation

of the cam 118 is prevented, and consequently rotation of the actuation plate 102 is prevented.
Figures 5 and 6 illustrate the coupling mechanism in accordance with a third embodiment. The actuating plate 102 is provided with two sets of actuating pins 104, 144, The cam 118 is sized such that it extends across the chamber 110 at one portion while defining two cavities 124, 146 between the inner wall 112 of the chamber 110 and the cam 118 at another portion, as best seen in Figure 6. In the embodiment illustrated, the cavities 124, 146 are diametrically opposite each other, separated by the portion of the cam 118 extending across the chamber 110. A projection 126 extends in to each cavity 124, 146 towards the inner wall 112 of the housing 106. On either side of each projection 126, a sub cavity 132 is formed that is sized to receive the actuating pin 104, 144 of the actuating plate 102.
A pair of rollers 130, 136 is placed on each projection 126 between the projection 126 and the inner wall 112 of the chamber 110. On assembly, the actuating pins 104, 144 are received within the sub cavities 132 on either side of each projection 126 and may or may not be in contact with the rollers 130, 136.
Rotation of the actuating plate 102 in either direction causes diametrically opposite actuating pins 104, 144 to press against the corresponding rollers 130, 136. pushing the rollers 130, 136 against the spring 134 towards the central surface. When the rollers 130, 136 are pushed on to the central surface, they cease to function as a wedge and the cam 118 is permitted to rotate. Rotation of the cam 118 causes the driven shaft 116 to rotate and thus rotation of the actuating plate 102 is transmitted to the driven shaft 116. On the other hand, rotating the driven shaft 116 in any direction, attempting to rotate the camlI8, causes diametrically opposite rollers 130, 136 to further move away from the central surface and get

wedged between the cam 118 and the inner wall 112 of the chamber 110. As a result, rotation of the cam 118 is prevented, and consequently rotation of the actuation plate 102 is prevented.
With reference to figures 7 and 8, a coupling mechanism in accordance with a fourth embodiment is illustrated. The actuating plate 102 may be a part of a driving shaft 116 that is connected to the throttle lever 200. The fourth embodiment is a modification of the third embodiment on the lines of the second embodiment. In addition to the pair of projections 126, the cam 118 is provided with at least one dowel pin 138 projecting towards the actuating plate 102. In the embodiment illustrated, a pair of dowel pins 138, 142 is provided on the cam 118 that project towards the actuating plate 102. The actuating plate 102 is provided with corresponding openings 140 formed thereon that receive the dowel pins 138. 142. The openings 140 on the actuating plate 102 are sized larger than the dowel pins 138. 142. such that on assembly a clearance is created between the dowel pins 138, 142 and the edges of the opening 140.
Rotation of the actuating plate 102 in either direction causes diametrically opposite actuating pins 104, 144 to press against the corresponding rollers 130, 136, pushing the rollers 130, 136 against the spring 134 towards the central surface. When the rollers 130, 136 are pushed on to the central surface, they cease to function as a wedge and the cam is permitted to rotate. Rotation of the cam 118 causes the driven shaft 116 to rotate and thus rotation of the actuating plate 102 is transmitted to the driven shaft 116. Simultaneously, rotation of the actuating plate 102 to move the rollers 130, 136 on to the central surface causes the opening 140 of the actuating plate 102 to engage the dowel pins 138, 142, also causing the cam 118 to rotate. Rotation of the cam 118 causes the driven shaft 116 to rotate and thus rotation of the actuating plate 102 is transmitted to the driven shaft 116. Thus

rotation of the actuating plate 102 is transmitted to the cam 11 8 by both the rollers 130, 136 as well as the dowel pins 138, 142.
On the other hand, rotating the driven shaft 116 in any direction, attempting to rotate the cam 118. causes diametrically opposite rollers 130, 136 to further move away from the central surface and get wedged between the cam 118 and the inner wall 112 of the chamber 110. As a result, rotation of the cam 118 is prevented, and consequently rotation of the actuation plate 102 is prevented.
With reference to Figure 9, the actuating pins 104 are shown at the rest position. Clockwise rotation of the actuating plate 102 by two degrees results in the actuating pins 104 contacting the roller 136. A further rotation of two degrees results in the roller 136 pressing spring 134 and moving towards the central surface 150, as well as the opening 140 of the actuating plate 102 contacting the actuating pin 104. A four-degree rotation of the actuating plate 102 is sufficient to rotate the cam 118.
SPECIFIC EMBODIMENTS ARE DESCRIBED BELOW
A non-reaction coupling mechanism for coupling an actuating member to a driven shaft comprising a housing defining an opening to receive the driven shaft, a cam defining a radial projection positioned within the housing and mounted on the driven shaft; the radial projection comprising a central surface, a first side surface and a second side surface on either side of the central surface, such that the central surface defines a central clearance between the cam and the housing and the first side surface and the second side surface define side clearances between the cam and the housing; the side clearances smaller than the central clearance, a first roller and a second roller positioned between the radial projection and the housing and having a resilient member in between, the resilient member configured to position the first roller at least partly on the first side surface and the second roller at least

partly on the second side surface; the first and second rollers sized such that when partly or completely positioned on the side surface the rollers contact the housing and serve as a wedge between the cam and the housing and when positioned on the central surface a gap is formed between the rollers and the housing and a first actuating pin and a second actuating pin mounted on the actuating member and configured to be received within the housing with the first actuating pin positioned between the cam and the first roller and the second actuating pin positioned between the cam and the second roller such that rotation of the actuating member causes one of the actuating pins to push the respective roller from the side surface towards the central surface against the resilient member.
Such non-reaction coupling mechanism(s), wherein the cam comprises of a first and second pin projecting axially outwards towards the actuating member and configured to be received in corresponding openings defined on the actuating member.
Such non-reaction coupling mechanism(s), wherein the openings on the actuating member are larger than the first and second pin defining a clearance there between such that rotation of the actuating plate by a predefined angle causes the actuating plate to engage with the pins.
Such non-reaction coupling mechanism(s), wherein the cam comprises of a second radial projection diametrically opposite and identical to the radial projection, the coupling mechanism further comprising of a third and fourth roller having a resilient member in between positioned on the second radial projection in a manner identical to the positioning of the first and second roller on the radial projection.
Such non-reaction coupling mechanism(s), wherein the cam comprises of a first and second pin projecting axially outwards towards the actuating member and configured to be received in corresponding slots defined on the actuating member.

Such non-reaction coupling mechanism(s), wherein the openings on the actuating member are larger than the first and second pin defining a clearance there between such that rotation of the actuating plate by a predefined angle causes the actuating plate to engage with the pins.
Such non-reaction coupling mechanism(s), wherein the housing is tubular.
Such non-reaction coupling mechanism(s), wherein the actuating member is coupled to a steering member such that torsional forces are transmitted only from the steering member to the driven shaft.
Such non-reaction coupling mechanism(s), wherein the central surface, first side surface and second side surface form a continuous surface on which the rollers may roll.
INDUSTRIAL APPLICABILITY
The coupling system may be used in various industries including industrial, construction, marine and mining for applications such as throttle, clutch, gearshifts and steering. Although, the coupling system has been described with reference to a steering application for boats, it would be apparent to a person in the art that the coupling system may be equally applied to other similar applications.
The coupling system provides a simple and efficient way of connecting an actuating and actuated member that prevents forces from being transmitted back to the actuating member.
While example embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims.

WE CLAIM:
1. A non-reaction coupling mechanism for coupling an actuating member to a driven shaft comprising:
a housing defining an opening to receive the driven shaft; a cam defining a radial projection positioned within the housing and mounted on the driven shaft; the radial projection comprising a central surface, a first side surface and a second side surface on either side of the central surface. such that the central surface defines a central clearance between the cam and the housing and the first side surface and the second side surface define side clearances between the cam and the housing; the side clearances smaller than the central clearance;
a first roller and a second roller positioned between the radial projection and the housing and having a resilient member in between, the resilient member configured to position the first roller at least partly on the first side surface and the second roller at least partly on the second side surface; the first and second rollers sized such that when partly or completely positioned on the side surface the rollers contact the housing and serve as a wedge between the cam and the housing and when positioned on the central surface a gap is formed between the rollers and the housing; and
a first actuating pin and a second actuating pin mounted on the actuating member and configured to be received within the housing with the first actuating pin positioned between the cam and the first roller and the second actuating pin positioned between the cam and the second roller; such that rotation of the actuating member causes one of the actuating pins to push the

respective roller from the side surface towards the central surface against the resilient member.
2. A non-reaction coupling mechanism as claimed in claim 1 wherein the cam comprises of a first and second pin projecting axially outwards towards the actuating member and configured to be received in corresponding openings defined on the actuating member.
3. A non-reaction coupling mechanism as claimed in claim 2 wherein the openings on the actuating member are larger than the first and second pin defining a clearance there between such that rotation of the actuating plate by a predefined angle causes the actuating plate to engage with the pins.
4. A non-reaction coupling mechanism as claimed in claim 1 wherein the cam comprises of a second radial projection diametrically opposite and identical to the radial projection, the coupling mechanism further comprising of a third and fourth roller having a resilient member in between positioned on the second radial projection in a manner identical to the positioning of the first and second roller on the radial projection,
5. A non-reaction coupling mechanism as claimed in claim 4 wherein the cam comprises of a first and second pin projecting axially outwards towards the actuating member and configured to be received in corresponding slots defined on the actuating member.

6. A non-reaction coupling mechanism as claimed in claim 5 wherein the openings on the actuating member are larger than the first and second pin defining a clearance there between such that rotation of the actuating plate by a predefined angle causes the actuating plate to engage with the pins.
7. A non-reaction coupling mechanism as claimed in any preceding claim wherein the housing is tubular.
8. A non-reaction coupling mechanism as claimed in any preceding claim wherein the actuating member is coupled to a steering member such that torsional forces are transmitted only from the steering member to the driven shaft.
9. A non-reaction coupling mechanism as claimed in any preceding claim wherein the central surface, first side surface and second side surface form a continuous surface on which the rollers may roll.
10. A non-reaction coupling mechanism substantially as herein described with reference to and as illustrated in the accompanying drawings.