Neutral position limit switch head design with reduced parts and improved reliability

Abstract

The present invention is entitled "Neutral position limit switch head design with reduced components and improved reliability". The present invention relates to a limit switch operating head, which includes a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft; and a follower actuated by the cam member in response to the rotation of the cam member, wherein the follower includes a pivot pin, a lever portion capable of pivoting around the pivot pin, and a rolling pin mounted to the lever portion and contacting the cam member. The actuator member contacts the lever portion and linearly translates in a first direction or a second direction in response to the pivoting of the lever portion. The rolling pin moves along the profile of the cam member when the cam member rotates so as to pivot the lever portion, wherein the actuator member linearly translates in a first direction or a second direction in response to the pivoting of the lever portion.

Description

Background Art

[0001] The present invention relates generally to limit switches and, more particularly, to a neutral position limit switch including a simplified head assembly design with fewer moving parts.

[0002] Electric limit switches include a widely used class of switch devices for selectively completing and / or interrupting one or more electrical connections according to the position of a displaceable switch sensing member. Many electric limit switches include a head assembly that incorporates a rotary actuator that converts rotary motion into linear motion to actuate the limit switch. A typical head assembly has a crank or other lever for rotating an actuator shaft, and an output member driven by the actuator shaft, the output member having a linear output motion. The output member engages and drives an element of the displaceable switch sensing member for selectively completing and / or interrupting one or more electrical connections. In some embodiments, the electric limit switch can be configured as a neutral position switch, wherein the actuator shaft of the head assembly can rotate in both a clockwise direction and a counterclockwise direction to achieve the movement of the output member and the corresponding translation of the displaceable switch sensing member from a neutral position to two different positions in different modes.

[0003] However, it should be recognized that the head assembly of the above-described design as currently constructed has certain disadvantages in terms of its operating characteristics and construction where such disadvantages are of concern. For example, a neutral position limit switch in which the actuator shaft of the head assembly is capable of rotating in both a clockwise and counterclockwise direction typically requires a large degree of pre-travel rotation of the actuator shaft (e.g., approximately 15°-20°) before the rotation is converted into linear motion of the output member, which results in an increased switching / tripping time of the limit switch. Although such a large degree of pre-travel rotation can be reduced, the head assembly is typically made more complex by having more complex moving parts, such as by having separate cam members and providing for mounting these cam members in different orientations relative to the actuator shaft and the output member to obtain the desired operation. Therefore, it should be recognized that a head assembly having such a construction includes a large number of moving parts, which increases the cost and complexity of the head assembly and can lead to reliability issues in the field.

[0004] Therefore, it is desirable to provide a head assembly for a neutral position limit switch that requires a smaller degree of pre-travel rotation of the actuator shaft (e.g., approximately 5°) before the rotation is converted into linear motion of the output member to provide a faster switching / tripping time for the limit switch. It is also desirable to provide a head assembly that achieves this reduced degree of pre-travel rotation through a simplified head assembly design that has a reduced number of moving parts, which will require less time and cost to assemble them and will enhance the reliability of the limit switch due to the reduction in moving parts therein. Summary of the invention

[0005] According to one aspect of the present invention, an operating head for providing actuation in a limit switch includes a housing, a shaft capable of rotating in a clockwise direction and a counterclockwise direction, a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft, and a follower actuated by the cam member in response to the rotation of the cam member in the clockwise direction and the counterclockwise direction, wherein the follower also includes a pivot pin fixed to the housing, a lever portion positioned on the pivot pin and capable of pivoting in opposite directions around the pivot pin, and a rolling pin mounted to the lever portion and in contact with the cam member. The operating head also includes an actuator member that contacts the lever portion and linearly translates in a first direction or a second direction in response to the pivoting of the lever portion. When the cam member rotates in a clockwise direction or a counterclockwise direction, the rolling pin moves along the profile of the cam member so as to pivot the lever portion, wherein the actuator member linearly translates in a first direction or a second direction in response to the pivoting of the lever portion.

[0006] According to another aspect of the present invention, an electric limit switch includes a switch subassembly having a plurality of fixed electrical terminals and a contact carrier including an electrical contact thereon, the contact carrier being capable of moving between a plurality of different switch positions to selectively transfer the position of the electrical contact to different electrical terminals to make and disconnect different circuits in the switch subassembly. The electric limit switch also includes an operating head subassembly having a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft; an actuator member, the actuator member being configured to be capable of linearly moving in a first direction or a second direction in response to the rotation of the cam member in a clockwise direction or a counterclockwise direction to cause a corresponding movement of the contact carrier; and a follower, the follower being in contact with each of the cam member and the actuator member to convert the rotation of the cam member in a clockwise direction or a counterclockwise direction into a linear movement of the actuator member in a first direction or a second direction, wherein the follower directly actuates the actuator member.

[0007] According to another aspect of the present invention, an operating head for providing actuation in a limit switch includes a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft; and an actuator member, which moves linearly from a vertical position in a first direction or a second direction in response to the rotation of the cam member in a clockwise direction or a counterclockwise direction, and the actuator member can move between a first actuation position and a second actuation position. The operating head also includes a follower in contact with each of the cam member and the actuator member to convert the rotation of the cam member in a clockwise direction or a counterclockwise direction into a linear movement of the actuator member in a first direction or a second direction. In operation of the operating head, the shaft has a pre-travel rotation of approximately 5° to move the actuator member to the first actuation position and the second actuation position.

[0008] Various other features and advantages of the present invention will become apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The drawings illustrate preferred embodiments presently contemplated for carrying out the invention.

[0010] In the attached picture:

[0011] Figure 1 is a perspective view of a neutral position limit switch according to an embodiment of the present invention.

[0012] Figure 2 According to an embodiment of the present invention Figure 1 A perspective view of the operating head of a neutral position limit switch, which is shown in dotted lines.

[0013] Figure 3 is along Figure 2 A cross-sectional view of the operating head taken along line 3-3.

[0014] Figure 4 yes Figure 2 A schematic diagram of an operating head is shown in FIG. 1 , which shows the operating head in a vertical state or position.

[0015] Figure 5 yes Figure 2 Schematic diagram of an operating head showing the operating head when its rotatable shaft rotates in a clockwise direction.

[0016] Figure 6 yes Figure 2 Schematic diagram of an operating head showing the operating head when its rotatable shaft rotates in a counterclockwise direction. DETAILED DESCRIPTION

[0017] Embodiments of the present invention provide a neutral position limit switch having a simplified head assembly with a reduced number of moving parts and improved reliability. The head assembly is configured with an actuator shaft that, when rotated, causes rotation of a single cam and corresponding pivoting of a follower based on the interface between the cam and the rolling pin of the follower. Only a small degree of pre-travel rotation of the actuator shaft (e.g., approximately 5°) is required before the cam rotates sufficiently to interact with the rolling pin and convert the rotation into linear motion of the output member, resulting in actuation of the limit switch.

[0018] See also Figure 1 , a neutral position limit switch 10 according to an embodiment of the present invention is shown. The neutral position limit switch 10 includes an operating head subassembly 12 and a switch subassembly 14. The operating head 12 is retained on the switch subassembly by four screws (not shown), one at each corner, and can be separated therefrom by removing such screws. In operation, the limit switch 10 can selectively control the completion and / or interruption of one or more electrical connections based on the position of a displaceable switch sensing member in the switch subassembly 14, as will be explained in more detail below.

[0019] Embodiments of the present invention are particularly directed to the mechanisms contained within the operating head 12, and thus Figure 2 and Figure 3 1 shows a more detailed view of the operating head 12. As shown therein, the operating head 12 is generally configured to include an outer housing 16, a top cover 18, a rotatable shaft 20, an actuator member 22, a cam member 24, a follower 26, a stop 28, and a return mechanism (e.g., a coil spring) 30. The shaft 20 extends from the exterior of the housing 16 and passes through a sleeve bearing 32 into the interior of the housing 16, wherein the shaft 20 extends through an opening 34 in the cam member 24 and is pivotally seated in a mounting seat or sleeve bearing 36 formed in the housing 16 opposite the sleeve bearing 32. Although not shown in FIG. Figure 2 and Figure 3 2, but it is recognized that the neutral position limit switch 10 will include an operating arm mounted at an angle on the shaft 20 and fixed thereto (e.g., by tightening screws) to provide rotation of the shaft 20, as is known in the art. The operating arm may include a roller for engagement by a moving machine part or the like, which causes rotation of the operating arm and corresponding rotation of the shaft 20.

[0020] The shaft 20 is configured as a generally circular cylindrical member and has a semicircular portion, wherein the shaft 20 has a flat drive surface 38 in an area where it is seated within the cam member 24, so that rotation of the shaft 20 imparts rotation to the cam member 24. The shaft 20 also includes a recess 40 formed therein to receive the stopper 28, wherein the stopper 28 is seated on a flat surface in the recess 40, so that the stopper 28 can be oriented / arranged to be flush with the shaft 20. The stopper 28 is centered on the shaft 20 and mounted relative to the shaft by a pair of guide pins 41. The stopper 28 is aligned on the guide pins 41 via an opening included in the stopper 28 on opposite ends thereof, wherein the stopper 28 linearly translates along the guide pins 41 in response to rotation of the shaft 20. The coil spring 30 is positioned adjacent to the stopper 28 and within the recess 40, the coil spring having one end of the coil spring 30 mounted to the inner surface of the housing 16 and an opposite end of the coil spring 30 in contact with the stopper 28. The coil spring 30 serves to bias the stop 28 and the shaft 20 to a neutral position when no rotational force / torque is applied to the shaft 20 , as will be explained in greater detail below.

[0021] like Figure 3 As best shown, the follower 26 is generally comprised of a lever portion 42, a pivot pin 44, and a rolling pin 46. The pivot pin 44 is attached to the housing 16 and cooperates with an opening 47 formed in the lever portion 42 to provide for rotation of the lever portion 42 about the pivot pin 44. The lever portion 42 extends outwardly from the location of the pivot pin 44 and is aligned to be positioned adjacent to and between the cam member 24 and the actuator member 22. A first surface 48 of the lever portion 42 abuts the actuator member 22 and is formed as a generally flat surface, wherein the surface 48 interacts with the actuator member 22 to cause movement thereof when the lever portion 42 is rotated. The rolling pin 46 is fixed to the lever portion 42, which is generally adjacent to a second surface 50 thereof opposite the first surface 48. The rolling pin 46 is inserted into an opening 52 formed in the lever portion 42, wherein the opening 52 is formed in the lever portion 42 at a location longitudinally positioned between the location of the pivot pin 44 and the location where the actuator member 22 abuts the lever portion 42. The lever portion 42 is thicker at this location to form an opening 52 therein and receive the rolling pin 46 within the opening 52. The rolling pin 46 extends outwardly from the opening 52 in the lever portion 42 to abut the cam member 24 and allow interaction between the follower 26 and the cam member 24.

[0022] Likewise Figure 3As best shown in FIG. 1 , the cam member 24 comprises a disc cam or a flat plate cam and has a cam profile that is shaped to include a protrusion 54 that slopes from a reduced diameter cam surface 56 to an increased diameter cam surface 58. The shaft 20 is seated within the opening 34 of the cam member 24 in a manner (e.g., a friction fit) such that the cam member 24 is fixed to the shaft 20 at a desired position. The cam member 24 is positioned relative to the follower 26 such that the rolling pin 46 of the follower 26 floats at a half-point on the sloped protrusion 54 of the cam member 24, which corresponds to the neutral position of the operating head 12 and the limit switch 10. Thus, rotation of the cam member 24 in a clockwise direction causes the rolling pin 46 to move downwardly along the sloped protrusion 54 of the cam member 24 to the reduced diameter cam surface 56, while rotation of the cam member 24 in a counterclockwise direction causes the rolling pin 46 to move upwardly along the sloped protrusion 54 of the cam member 24 to the increased diameter cam surface 58. Therefore, movement of the lever portion 42 of the follower 26 in an upward or downward manner is achieved when the cam member 24 rotates.

[0023] After the cam member 24 rotates in a clockwise or counterclockwise direction and the corresponding upward or downward movement of the lever portion 42 of the follower 26, the actuator member 22 in contact with the lever portion 42 is also caused to move from a vertical position or a non-biased position. That is, the actuator member 22 can slide inwardly or outwardly along a linear path based on the movement of the follower 26, wherein the actuator member 22 can move between a fully actuated position, which is generally referred to as a first actuation position, and a second actuation position, each of which causes the tripping of the limit switch 10. According to an exemplary embodiment, the actuator member 22 is positioned so as to be adjacent to the end of the lever portion 42 and so as to be misaligned with the axis about which the follower member 26 rotates (i.e., the center axis of the force rotation of the shaft 20). This positioning of the actuator member 22 away from the center axis of the force rotation reduces the torque level required to be applied to the rotating shaft 20 and reduces the force transmitted between the cam member 24 and the rolling pin 46.

[0024] When the actuator member 22 is moved by the follower 26, the actuator member 22 slides along / in the opening 60 in the top cover 18 to provide linear actuation to the components of the switch subassembly 14, wherein the top cover 18 provides a guide for the actuator member 22. Figure 4As shown, the actuator member 22 extends into the switch housing 62 of the switch subassembly 14 (via a bushing 64 formed in the switch housing 62) and causes relative movement of its contact carrier 66. More specifically, according to an exemplary embodiment, the actuator member 22 abuts against the plunger 68 in the switch subassembly 14 aligned therewith to cause linear movement of the plunger 68, which in turn causes relative movement of the contact carrier 66. The contact carrier 66 shifts the position of the contact 70 in the switch subassembly 14 to different terminals 72 to make or break different circuits in the switch subassembly 14. That is, the contact carrier 66 shifts the position of the contact 70 to different terminals 72 based on the inward or outward movement of the actuator member 22 to the first actuation position and the second actuation position to make or break different circuits in the two-step switch of the switch subassembly 14. A compression spring 74 is disposed between the bottom side of the switch housing 62 and the bottom of the plunger 68 to push the plunger 68 and the actuator member 22 and return to the vertical / neutral position.

[0025] Still see Figure 4 And now also see Figure 5 and Figure 6 , according to one embodiment of the present invention, illustrates the function of the operating head 12 in a vertical / neutral position and when the shaft 20 is rotated in a clockwise direction and a counterclockwise direction, respectively, and the interaction of the operating head 12 with the switch subassembly 14. Figure 4 First shown, the operating head 12 is in a vertical / neutral position, in which the cam member 24 is in a non-rotated position, so that the rolling pin 46 of the follower 26 floats at a half-point on the inclined protrusion 54 of the cam member 24. Therefore, the follower 26 (i.e., its lever portion 42) is also in a vertical / neutral position, and the actuator member 22 is also at rest in the vertical / neutral position. Therefore, the contact carrier 66 of the switch subassembly is in a non-biased position, and the contacts 70 thereon are positioned accordingly to make / break the circuit associated with the non-biased position.

[0026] See also Figure 5, the shaft 20 of the operating head 12 rotates in a clockwise direction. As the shaft 20 rotates, the cam member 24 rotates and begins to interact with the rolling pin 46, thereby initiating the pivoting of the follower 26 and the translation of the actuator member 22, so that the rotation of the shaft 20 reaches or exceeds a minimum rotation amount, such as exceeding a pre-travel of about 5° (i.e., a pre-travel of 5° + / - 2°), thereby rotating the cam member 24 by a certain amount to cause the actuator member 22 to move linearly to the first actuation position to trip the limit switch 10. Therefore, when the shaft 20 rotates in a clockwise direction exceeding the minimum rotation amount, the cam member 24 is rotated so that the rolling pin 46 of the follower 26 moves the inclined protrusion 54 of the cam member 24 completely downward to the cam surface of reduced diameter. This causes the lever portion 42 of the follower 26 to move / rotate backward toward the cam member 24 and the actuator member 22 to retract back to the housing 16 of the operating head 12 by a predetermined linear distance, i.e., to the first actuation position. Retracting the actuator member 22 to the first actuated position causes the plunger 68 of the switch subassembly to move the contact carrier 66 to the first biased position, wherein the contacts 70 thereon are correspondingly positioned to make / break the circuit associated with the first biased position.

[0027] See also Figure 6 , the shaft 20 of the operating head 12 rotates in a counterclockwise direction. As the shaft 20 rotates, the cam member 24 rotates and begins to interact with the rolling pin 46, thereby initiating the pivoting of the follower 26 and the translation of the actuator member 22, so that the rotation of the shaft 20 reaches or exceeds a minimum rotation amount (e.g., exceeds a pre-travel of about 5°), so that the amount of rotation of the cam member 24 causes the actuator member 22 to move linearly to the second actuation position to trip the limit switch 10. Therefore, when the shaft 20 rotates in a counterclockwise direction exceeding the minimum rotation amount, the cam member 24 rotates so that the rolling pin 46 of the follower 26 moves the inclined protrusion 54 of the cam member 24 completely upward to the cam surface of the increased diameter. This causes the lever portion 42 of the follower 26 to move / rotate outwardly and away from the cam member 24 and the actuator member 22 to extend further outwardly from the housing 16 of the operating head 12 accordingly, i.e., to reach the second actuation position. Extension of the actuator member 22 to the second actuated position causes the plunger 68 of the switch subassembly to move the contact carrier 66 to the second biased position, wherein the contacts 70 thereon are correspondingly positioned to make / break the circuit associated with the second biased position.

[0028] With respect to the movement of the actuator member 22 caused by the follower 26 when the rotation of the cam member 24 exceeds the specified pre-travel amount, the positioning of the actuator member 22 will remain in its actuated position during another 85°-90° of post-travel of the cam member 24 in the same direction, or until the torque / rotational force on the shaft 20 and cam member 24 is terminated and the cam member 24 and follower 26 return to their vertical / neutral positions. In order to return the cam member 24 and follower 26 to their vertical / neutral positions, the coil spring 30 of the operating head 12 exerts a force on the stop 28 and causes the stop 28 to slide on the guide pin 41 and exert a force on the shaft 20, which in turn pushes the shaft 20 back to its vertical, non-rotated position—causing the cam member 24 and follower 26 to also return to their vertical / neutral positions. Thus, returning the cam member 24 and follower 26 to their vertical / neutral positions also returns the actuator member 22 to its stationary, vertical / neutral position, leaving the contact carrier 66 of the switch subassembly 14 in its unbiased position. This completes the operating cycle of the limit switch 10.

[0029] The construction of the operating head 12 and the arrangement of the components therein provide a number of benefits in the design of the present invention. First, positioning the rolling pin 46 at a half-point on the inclined protrusion 54 of the cam member 24 in the neutral position provides a limit switch 10 with only a small amount of pre-travel rotation (e.g., approximately 5°) of the actuator shaft 20 before the cam member 24 is fully rotated to cause the limit switch 10 to trip, under the interaction of the cam member 24 with the rolling pin 46 of the follower 26 within the pre-travel range (i.e., 0°-5°) (and the linear movement of the actuator member 22). This small amount of required pre-travel allows the switch subassembly 14 to switch / trip more quickly in the limit switch 10. In addition, the use of the rolling pin 46 in the follower 26—and its interaction with the cam member 24—reduces the friction between the follower 26 and the cam member 24 as the cam member 24 rotates. This reduction in friction—generally along with the shape and pivoting nature of the follower 26—allows for an acceptable larger wobble in the interaction between the follower 26 and the cam member 24 over a range of cam pressure angles (e.g., between 30° and 45°). Additionally, positioning the actuator member 22 so that it is not aligned with the axis about which the follower member 26 rotates (i.e., the center axis of rotation of the disengagement force) reduces the level of torque required to be applied to the rotating shaft 20 and reduces the force transmitted between the cam member 24 and the rolling pin 46. The reduction in the level of torque required to rotate the cam member 24 is desirable for reducing the forces in the operating head 12 and increasing the life of the operating head 12.

[0030] Advantageously, embodiments of the present invention therefore provide a neutral position limit switch having an operating head subassembly having a simplified design with a reduced number of moving parts, which requires less time and cost to assemble them, and enhances the reliability of the limit switch due to the reduction in moving parts therein. The operating head subassembly requires only a small degree of pre-travel rotation of the actuator shaft (e.g., close to 5°) before the rotation is sufficient to linearly translate the output member to the fully actuated position, so as to provide a faster switching / tripping time for the limit switch. In addition, the construction of the operating head subassembly provides its required functionality in a confined small space (i.e., a compact operating head subassembly). Thus, the beneficial effect of a simplified design with a reduced number of moving parts is achieved, which enhances the reliability of the limit switch without having to increase the outer boundaries / size of the operating head subassembly.

[0031] Therefore, according to one embodiment of the present invention, an operating head for providing actuation in a limit switch includes a housing, a shaft capable of rotating in a clockwise direction and a counterclockwise direction, a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft, and a follower actuated by the cam member in response to the rotation of the cam member in the clockwise direction and the counterclockwise direction, wherein the follower also includes a pivot pin fixed to the housing, a lever portion positioned on the pivot pin and capable of pivoting in opposite directions around the pivot pin, and a rolling pin mounted to the lever portion and in contact with the cam member. The operating head also includes an actuator member that contacts the lever portion and linearly translates in a first direction or a second direction in response to the pivoting of the lever portion. When the cam member rotates in a clockwise direction or a counterclockwise direction, the rolling pin moves along the profile of the cam member so as to pivot the lever portion, wherein the actuator member linearly translates in a first direction or a second direction in response to the pivoting of the lever portion.

[0032] According to another embodiment of the present invention, an electric limit switch includes a switch subassembly having a plurality of fixed electrical terminals and a contact carrier including an electrical contact thereon, the contact carrier being able to move between a plurality of different switch positions to selectively transfer the position of the electrical contact to different electrical terminals to make and disconnect different circuits in the switch subassembly. The electric limit switch also includes an operating head subassembly having a shaft that can rotate in a clockwise direction and a counterclockwise direction. A cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft; an actuator member, the actuator member being configured to be able to linearly move in a first direction or a second direction in response to the rotation of the cam member in a clockwise direction or a counterclockwise direction to cause a corresponding movement of the contact carrier; and a follower, the follower being in contact with each of the cam member and the actuator member to convert the rotation of the cam member in a clockwise direction or a counterclockwise direction into a linear movement of the actuator member in a first direction or a second direction, wherein the follower directly actuates the actuator member.

[0033] According to another embodiment of the present invention, an operating head for providing actuation in a limit switch includes a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and capable of rotating in a clockwise direction and a counterclockwise direction in response to the rotation of the shaft; and an actuator member, the actuator member moves linearly from a vertical position in a first direction or a second direction in response to the rotation of the cam member in a clockwise direction or a counterclockwise direction, and the actuator member can move between a first actuation position and a second actuation position. The operating head also includes a follower in contact with each of the cam member and the actuator member to convert the rotation of the cam member in a clockwise direction or a counterclockwise direction into a linear movement of the actuator member in a first direction or a second direction. In operation of the operating head, the shaft has a pre-travel rotation of approximately 5° to move the actuator member to the first actuation position and the second actuation position.

[0034] The present invention has been described in terms of preferred embodiments, and it is recognized that equivalents, alternatives and modifications, aside from those explicitly stated, are possible and within the scope of the appended claims.

Claims

1. An operating head for providing actuation in a limit switch, the operating head comprising: shell; a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and rotatable in the clockwise and counterclockwise directions in response to rotation of the shaft; a follower actuated by the cam member in response to rotation of the cam member in the clockwise and counterclockwise directions, the follower comprising: a pivot pin secured to the housing; a lever portion positioned on the pivot pin and including an opening, the lever portion being pivotable in opposite directions about the pivot pin; and a rolling pin inserted into the opening of the lever portion and extending outward from the opening, the rolling pin being in contact with the cam member through a circumferential surface thereof; and an actuator member that contacts the lever portion and linearly translates in a first direction or a second direction in response to pivoting of the lever portion; The rolling pin moves along the profile of the cam member when the cam member rotates in the clockwise direction or the counterclockwise direction to pivot the lever portion, wherein the actuator member linearly translates in the first direction or the second direction in response to the pivoting of the lever portion.

2. An operating head according to claim 1, wherein the cam profile of the cam member includes a protrusion that slopes from a cam surface with a reduced diameter to a cam surface with an increased diameter, and wherein when the operating head is in a vertical operating position, the rolling pin floats at a half-point on the inclined protrusion.

3. An operating head according to claim 2, wherein when the cam member rotates in the clockwise direction, the rolling pin moves downward along the inclined protrusion to the cam surface with reduced diameter, thereby causing the lever part to pivot toward the cam member and the actuator member to linearly translate in the first direction.

4. An operating head according to claim 2, wherein when the cam member rotates in the counterclockwise direction, the rolling pin moves upward along the inclined protrusion to the cam surface with increased diameter, thereby causing the lever portion to pivot away from the cam member and the actuator member to linearly translate in the second direction.

5. An operating head according to claim 2, wherein when the shaft is rotated 5° along the clockwise or counterclockwise pre-stroke, the rolling pin moves from the half point on the inclined protrusion to the cam surface with reduced diameter or the cam surface with increased diameter so as to move the actuator member to the first position or the second position.

6. An operating head according to claim 5, wherein after the shaft moves the rolling pin to a 5° pre-stroke rotation of the cam surface with reduced diameter or the cam surface with increased diameter, the rolling pin moves along the cam surface with reduced diameter or the cam surface with increased diameter to cause the shaft to perform another 85° to 90° post-stroke rotation in the same direction.

7. An operating head according to claim 1, wherein the actuator member is positioned so as to be misaligned with an axis about which the follower member rotates.

8. The operating head of claim 1, wherein the shaft includes a notch formed therein, and wherein the operating head further includes: a stopper positioned in the recess so as to contact the shaft; and a coil spring abutting the stop on one end and the housing on an opposite end; Wherein the coil spring is used to bias the stopper and shaft to a vertical operating position when no rotational force is applied to the shaft.

9. The operating head according to claim 1, wherein when moving along the profile of the cam member, the rolling pin rolls along the profile so as to reduce friction between the follower and the cam member.

10. An electric limit switch, comprising: A switch subassembly, the switch subassembly comprising: a plurality of fixed electrical terminals; and a contact carrier including electrical contacts thereon, the contact carrier being movable between a plurality of different switch positions to selectively shift the positions of the electrical contacts to different electrical terminals to make and break different circuits in the switch subassembly; and An operating head subassembly, the operating head subassembly comprising: a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and rotatable in the clockwise and counterclockwise directions in response to rotation of the shaft; an actuator member configured to be linearly movable in a first direction or a second direction in response to rotation of the cam member in the clockwise direction or the counterclockwise direction, wherein movement of the actuator member causes corresponding movement of the contact carrier; and A follower, the follower comprising a lever portion and a rolling pin, the rolling pin extending outward from an opening in the lever portion, the rolling pin contacting the cam member through its circumferential surface, and the follower contacting the actuator member to convert the rotation of the cam member in the clockwise or counterclockwise direction into linear motion of the actuator member in the first direction or the second direction, wherein the follower directly actuates the actuator member.

11. The electric limit switch according to claim 10, wherein the follower comprises: a pivot pin secured to a housing of the operating head subassembly; a lever portion positioned on the pivot pin and pivotable in opposite directions about the pivot pin, the lever portion contacting the actuator member to permit movement thereof; and a rolling pin mounted to the lever portion and in contact with the cam member; The rolling pin moves along the profile of the cam member when the cam member rotates in the clockwise direction or the counterclockwise direction to pivot the lever portion, wherein the actuator member linearly translates in the first direction or the second direction in response to the pivoting of the lever portion.

12. An electric limit switch according to claim 11, wherein the cam profile of the cam member includes a protrusion that slopes from a cam surface of reduced diameter to a cam surface of increased diameter, and wherein when the operating head is in the vertical operating position, the rolling pin floats at a half-point on the inclined protrusion.

13. An electric limit switch according to claim 12, wherein when the cam member rotates in the clockwise direction, the rolling pin moves downward along the inclined protrusion to the cam surface of reduced diameter, thereby causing the lever portion to pivot toward the cam member and the actuator member to linearly translate in the first direction.

14. An electric limit switch according to claim 12, wherein when the cam member rotates in the counterclockwise direction, the rolling pin moves upward along the inclined protrusion to the cam surface with increased diameter, thereby causing the lever portion to pivot away from the cam member and the actuator member to linearly translate in the second direction.

15. An electric limit switch according to claim 12, wherein when the shaft is rotated 5° along the clockwise or counterclockwise pre-stroke, the rolling pin moves from the half point on the inclined protrusion to the cam surface with reduced diameter or the cam surface with increased diameter, so as to enable the movement of the contact carrier to move to one of the multiple different switching positions.

16. The electrical limit switch of claim 11, wherein the actuator member is positioned so as to be adjacent an end of the lever portion and offset from the center of a central force axis about which the follower rotates.

17. The electrical limit switch of claim 10, wherein the switch subassembly further comprises a plunger aligned with the actuator member and configured to be linearly movable in response to a force applied thereto by the actuator member, the plunger abutting the contact carrier to cause movement thereof.

18. An operating head for providing actuation in a limit switch, the operating head comprising: a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a cam member supported on the shaft and rotatable in the clockwise and counterclockwise directions in response to rotation of the shaft; an actuator member that moves linearly from a vertical position in a first direction or a second direction in response to rotation of the cam member in the clockwise direction or the counterclockwise direction, the actuator member being movable between a first actuation position and a second actuation position; and a follower in contact with each of the cam member and the actuator member to convert the rotation of the cam member in the clockwise direction or the counterclockwise direction into a linear motion of the actuator member in the first direction or the second direction, the follower comprising a lever portion and a rolling pin extending outwardly from an opening in the lever portion, the rolling pin being in contact with the cam member through a circumferential surface thereof; Wherein the shaft has a pre-travel rotation of approximately 5° to move the actuator member to the first actuation position or the second actuation position.

19. The operating head according to claim 18, wherein the follower comprises: a pivot pin secured to a housing of the operating head; a lever portion positioned on the pivot pin and capable of pivoting in opposite directions about the pivot pin; and a rolling pin mounted to the lever portion and in contact with the cam member; The rolling pin moves along the profile of the cam member when the cam member rotates in the clockwise direction or the counterclockwise direction to pivot the lever portion, wherein the actuator member linearly translates in the first direction or the second direction in response to the pivoting of the lever portion.

20. An operating head as claimed in claim 18, wherein the actuator member is positioned so as to be out of alignment with the axis about which the follower member rotates.

21. An operating head, comprising: a shaft capable of rotating in a clockwise direction and a counterclockwise direction; a follower including a rolling pin and a lever portion positioned on a pivot pin, wherein the rolling pin extends outwardly from an opening in the lever portion; a cam member rotatable in the clockwise and counterclockwise directions in response to rotation of the shaft, the cam member comprising a cam surface including: a cam surface with a reduced diameter, a cam surface with an increased diameter, and an inclined portion between the cam surface with a reduced diameter and the cam surface with an increased diameter; as well as an actuator member that moves linearly from a vertical position in a first direction or a second direction in response to rotation of the cam member in the clockwise direction or the counterclockwise direction, When the operating head is in a vertical operating position, the rolling pin rests on the inclined portion without contacting the cam surface with reduced diameter or the cam surface with increased diameter.

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