US3568631A

US3568631A - Indicator mechanism

Info

Publication number: US3568631A
Application number: US827465A
Authority: US
Inventors: Harvey G Skinner
Original assignee: WESTMORELAND PLASTICS Inc
Current assignee: UMEC Corp; WESTMORELAND PLASTICS Inc
Priority date: 1969-05-02
Filing date: 1969-05-02
Publication date: 1971-03-09
Anticipated expiration: 1988-03-09
Also published as: GB1292798A

Abstract

I disclose an indicating mechanism comprising a support means on said support for defining an indicator path means and a drive member recess, said path means communicating with said recess, a drive member rotatably mounted within said recess, and an elongated flexible indicator joined to said drive member and at least partially wrapped thereabout, said indicator extending from said recess into and along said path means.

Description

United States Patent 2,014,485 9/1935 Themar Inventor Harvey G. Skinner Ligonier, Pa.

May 2, 1969 Mar. 9, 1971 Westmoreland Plastics Inc.

Latrobe, Pa.

Appl. No. Filed Patented Assignee INDICATOR MECHANISM 16 Claims, 10 Drawing Figs.

U.S.Cl 116/135, 116/115,116/133 Int. Cl G091 5/00 FieldofSearch 116/124, 124.1, 133, 135, 115, 115.5; 73/305;

74/(Inquired); 219/(lnquired); 338/(Inquired) References Cited UNITED STATES PATENTS 2,232,057 2/1941 Fa1lereta1.... 116/135 2,348,362 5/1944 Rudolf 73/305X 2,529,832 11/1950 Brietzke 116/135 2,529,833 11/1950 Brietzke 116/135 2,538,188 1/1951 Brietzke 116/135 3,040,700 6/1962 Smith, Jr. 1 16/135 3,139,854 7/1964 Hedges et a1. 116/135 Primary ExaminerLouis .I. Capozi AttorneyBue1l, Blenko & Ziesenheim 57 v 47 a 1 N 15 IV 1 .-58 ./52 "234% 72 F q 6 56 NA 39 16 a 0 1- -52 X 45 1? I T? 14 PATENTEDMAR BIS?! 3568.631

SHEET 1 UF 2 PATENTED MAR 9 mm SHEET 2 0F 2 n a w an i W W MG a 4 H W.

rnnrcnron MECHANISM The present invention relates to an indicator mechanism and more particularly to a mechanism of this character for translating rotary motion of relatively small radius to an external, larger scale movement for indicating purposes.

in the construction and use of various types of electrical equipment, a control or console panel frequently is provided. These panels or consoles frequently contain a number of rotary controls secured to the inside of the panel and having an operator knob protruding therethrough. The gas or electrical controls may involve variable resistances, conductances, capacitances, rotary switches and the like which are electrically connected to circuitry forming part of the electrical equipment, or gas flow.

With the increasing complexity of modern electrical, gas, and electronic equipment, a logical tendency toward miniaturization follows. The small sizes of the control knobs render their scale indicia difficult to read, as the scale indicia conventionally are inscribed on the knob or disposed closely thereabout. Moreover, inaccuracy frequentlyresults in both the placement and reading of scale indicia where the size thereof is limited in this manner. An indicating needle or pointer affixed to the control knob, when used, is usually spaced from the scale indicia and thus engenders further inaccuracies from parallax. t

Considerable improvement'in readability, both from the standpoints of accuracy and facility, can be had if these scales are made larger and therefore more easily read and calibrated. It is particularly desirable to-have the movement ofthe rotary control translated into a movement of an indicator tape or the like disposed for movement along the path which is removed at least a short distance from the rotary control knob. Such path may be linear, curvalinear, or arcuate depending upon the space limitations imposed by the control panel or console construction.

Most importantly, it has been established that an operator can more easily follow, with greater accuracy, the indicating end of a movable tape or other flexible indicator rather than the motion of a pointer or other indicating member affixed to a control knob and movable over a scale printed on or otherwise afiixed to the panel. Additionally, the conventional scale may substantially surround the control knob, where the control has nearly a 360 rotation. The operatorss fingers, then, frequently obstruct a portion of the scale during adjustment of the control.

in the past there have been a number of attempts to solve this problem, for example the U. S. Pat. Nos. to Brietzke 2,529,832 and 2,529,833; Smith, Jr. 3,040,700; and Hedges et al. 3,139,854. Each of these references contemplates unwrapping a flexible indicating tape or member from a rotary component of the control device. The indicating tape is then forced into an external, usually liner linear, indicating path. None of these references, however, are capable of use with a rotary control device capable of an increasing function in the clockwise direction or interchangeably with such device capable of increasing function in the opposite direction without substantial changes in structure. Obviously, if a rotary control having an increasing function in the opposite direction were substituted for those shown in the foregoing references, the scale indicia along the external path of indicating tape would have to be reversed. This would render reading of the scale indicia confusing, particularly where both clockwise and counterclockwise indicator systems or devices were used on a given panel. in that case some of the scale indicia may be inverted relative to other indicia to make reading more difficult. The

prior art, moreover, does not disclose an indicator system I overcome these disadvantages of the prior art by providing a rotary control device from which an indicator tape or strip is unwrapped for movement into external path means for cooperation with scale indicia along such path means. In one arrangement of my invention, the path means are disposed for receiving the indicator tape from either a clockwise increasing control device or one which evidences an increasing function in the opposite direction. indicia associated with the path means do not have to be inverted irrespective of the rotational direction of the rotary control in'supplying increasing increments of the controlled function.

in other arrangements of my invention the path means are arranged in an arcuate fashion. A portion of the path means may be displaced from the control knob for easy reading by placing the path means and the associated scale indicia entirely above, below, or to one side of the control knob such that the scale is not obstructed by the user's fingers. In furtherance of this purpose the indicia portion of the arcuatepath means can be provided with substantially the same center of rotation as that of the rotary controluIn any event the necessity of substantially surrounding the control knob with small and difficult to read scale indicia is obviated. In accordance with a specific modification of my invention I arrange the external path means of the indicator tape to connect the indicia portion of the path means with a point on the wrap area of the rotary control by meansof a smooth curve, such as a spiral section or Archimedes curve.

Finally, I arrange my novel indicator mechanism as a unitary structure such that a control knob forming part thereof is retained on a control shaft, upon securing the mechanism to the panel on which the control is mounted. I also provide stop means, forming part of the indicator mechanism, for the control knob and hence for the control secured thereto.

I accomplish these desirable results by providing an indicating mechanism comprising a support means on said support for defining an indicator path means and a drive member recess, said path means communicating with said recess, a drive member rotatably mounted within said recess, and an elongated flexible indicator joined to said drive member and at least partially wrapped thereabout, said indicator extending from said recess into and along said path means.

I also desirably provide a similar indicating mechanism wherein said path means include a pair of indicating paths adjoined with said recess at locations remote from one another to provide indications of increasing function for a preselected one of clockwise and counterclockwise movements of said drive member.

I also desirably provide a similar indicating mechanism wherein said path means include an arcuate path spacedly and partially surrounding drive member.

I also desirably provide a similar indicating mechanism wherein said drive member is of discoidal configuration, said indicator is at least partially wrapped about the peripheral edge thereof, said indicator being positioned on said edge by the adjacent surfaces of said support and said defining means.

I also desirably provide a similar indicating mechanism wherein said support includes a transparent cover and a base member, said base member having said defining means thereon, and a detachable overlay indicia plate is sandwiched between said cover and said base member, said overlay plate having visual access means generally aligned with at least a portion of said path means.

I also desirably provide a similar indicating mechanism wherein portions of said defining means and of said drive member are disposed respectively to bearingly engage portions of said indicator to provide stops for respectively delimiting movements of said drive member and of a rotary control coupled thereto.

l also desirably provide a similar indicating mechanism includinga control knob for a rotary control mounted on said support and secured to said drive member for rotation therewith, means on said knob and said control for keying said knob to said control for rotation therewith, said control being mounted on an external support member, and means for mounting said support on said support member so that said knob is maintained in keyed engagement with said control.

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same.

In the accompanying drawings I have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same, wherein:

FIG. 1 is a front elevational view of one form of indicator mechanism arranged in accordance with my invention;

FIG. 2 is a side elevational view of the mechanism as shown in FIG. 1;

FIG. 3 is a rear elevational view of the mechanism as shown in FIG. 1 and taken along reference line III-III thereof;

FIG. 4 is a cross-sectional view of the apparatus as shown in FIG. 3 and taken along reference line IV-IV thereof:

FIG. 4A is a partial cross-sectional view of the apparatus as shown in FIG. 3 and taken along reference line IVA-IVA thereof;

FIG. 5 is a partial front elevational view of the mechanism of FIG. 1 and showing another position of the indicator;

FIG. 6 is a front elevational view of another form of my indicator mechanism with parts removed for clarity;

FIG. 6A is a similar front elevational view of the mechanism of FIG. 6 showing another position of the indicator and associated components;

FIG. 7 is another front elevational view of the indicator mechanism of FIG. 5 showing a cover plate and indicia overlay attached; and,

FIG. 8 is a sectional view of the mechanism generally as shown in FIG. 7 and taken along reference line VIII-VIII thereof.

Referring now more particularly to FIGS. 1-5 of the drawings the exemplary indicator mechanism 10 shown therein comprises a support 11 including a front panel plate 12, a base member 14, a drive wheel 16 and a flexible indicating strip 18. The base member 14 in this example is provided with a pair of securance studs 20 (FIG. 2) whereby the indicator mechanism 10 can be secured to a control or console panel 22, for example by a pair of Tinnermans clips 24.

The indicator mechanism 10 is located on the panel 22 for engagement with a rotary control device 26, which can be secured to the opposite side of the panel 22 in any conventional fashion. The control 26 may be provided with one or more electric leads 28 for connection to other circuit components (not shown) for controlling various electrical, fluid, or gas apparatus. In this example, the control 26 is provided with a keyed operating rod or shaft 30 which extends through

suitable apertures

31 and 32 in the base member 14 and the front panel 12 respectively. The shaft 39 likewise extends through a keying recess 34 (FIG. 2) in extension 35 of control knob 36. The knob extension 35 in turn is inserted through drive wheel 16, which is enclosed within recess member 37 in this example formed integrally on the base member 14. The drive wheel 16 is keyed at 38 to the knob extension 35 which in turn is keyed at flats 39 to the control shaft 30 for rotation therewith. The drive wheel is further enclosed between the base member 14 arid the cover plate 12. When the indicator mechanism 10 is mounted on the panel 22, on which the control 26 is mounted, the knob 36 is retained on the control shaft 30 by the studs 20 and clips 24, or other suitable securance means, which secure the mechanism 10 to the panel 22.

Although the drive wheel 16 is of discoidal configuration, in this example, the indicator strip 18 is maintained on the peripheral edge of the drive wheel by the close fitting relation of the recess-defining

portions

37, 37a and the adjacent surfaces of the base member 14 and the cover plate 12 as evident from FIGS. 1 and 2.

Adjoining the recess member 37 of the base member 14 are a number of

wall sections

40, 42 which with the

recess members

37, 37a can be formed integrally with the base member 14, for example by molding from a suitable plastic. The aforementioned mounting studs 20 can be similarly and integrally molded. The outer wall sections 42, in this example, are linear extensions of the recess member 37, while the inner wall sections 40 are connected at their lower ends (as viewed in FIG. 1) to the arcuate recess member section 37a. A pair of

indicator paths

44, 46 are thus defined respectively by the inner and

outer wall sections

40, 42 and adjacent surfaces of the base member 12 and panel 14. The

paths

44, 46 adjoin the drive wheel recess 48 at the communicating

areas

50, 52 respectively. The drive wheel recess 48, which generally surrounds the

apertures

31, 32 is substantially enclosed and defined by the

recess members

37, 37a and by the adjacent surfaces of the base member and

front plates

12, 14.

The cover plate 12 can be provided with one or more indicating slots for example the slot 45 through which the free end 47 of the indicating strip 18 is visible. An additional indicating slot as indicated by chain outline 49 can also be provided if desired in the cover plate 12 in the event that the indicator strip 13 is redirected into path 46 rather than path 44 as shown in FIG. 1. The alternate indicating slot 49 may be provided as a knockout, or a separate cover plate (not shown) having an indicator slot 49 in place of the slot 45 can be provided. The

alternative indicating paths

44, 45 provide for reversal of the indicating movement of the strip 18 as set forth in greater detail below.

Alternatively, the cover plate 14 an can be fabricated from a transparent material, and separate overlay plate 53 (FIG. 2) having the

slot

45 or 49 and the indicia 63 (described below) can be positioned between the cover plate 14 and the base member 12. To reverse the indicator movements, i.e., when shifting the indicator 18 from path 44 to path 46, the overlay plate simply is reversed for a corresponding shift in the indicator slot. The overlay plate conveniently can be provided with indicia 68 on both obverse and reverse sides for this purpose.

The drive wheel 16 desirably is provided with a pair of displaced connecting means to which the drive end 54 of the strip 18 alternatively can be secured. In this example the aforementioned connecting means include a pair of indents or slots 56, 58, and in this example the strip 18 is secured to the left or clockwise slot 56 so that a proper length of the indicator or strip 18 can be extended into path 44. In furtherance of this purpose the strip 18 is provided with a keying end portion 60 which is fitted into a complementarily shaped portion of the selected drive wheel slot 56 or 53. Depending upon the resiliency of the material forming a strip 18, the strip can be provided if desired with a living hinge or restricted section 62 to facilitate bending of the end portion 54 of the strip 18 around the adjacent corner 64 or 66 of the drive wheel 16.

At the low or start position of the control 26 and its operating shaft 30 the indicator strip is wrapped substantially around the entire peripheral edge of the drive wheel 16 (FIG. 1). The indicating end 47 of the strip 18 is protruded through the communicating area 50 between the drive wheel recess 48 and the clockwise indicating path 44. Accordingly the indicator end 47 of the strip 18 encounters increasing scale indicia 68 during clockwise movement of control knob 38 (solid arrow 70), as the function controlled by the control 26 is varied in the increasing direction. Atthe initial strip position or minimum indication (FIG. 3), the engagement of the strip bend 67 with the adjacent portion of the strip 18 urges this portion against the adjacent path defining wall section 42 to act as a stop for the drive wheel 16 and the control knob 36 and control shaft 30 keyed thereto. The lower or minimum limit of the function controlled by the rotary control 26 is thereby established, a very useful arrangement fo those instances when the rotary control 26 is lacking in integral stop or motion-delimiting means or when delimitation differing from that afforded by a given control is desired. Similarly, as shown in FIG. 4A, control movement can be delimited in the maximum direction by contact of the strip indicating end 47 with a stop member 69 formed by the top inside surface of the support 11. Although the indicator is relatively flexible, it is sufficiently rigid to resist buckling particularly in the communicating

area

50 or 52, where the indicator is only partially supported, at the adjaeent wall section 12. Throughout the remainder of the movement path of the strip 10, the latter is relatively closely confined between the

adjacent wall sections

40, 42 or between the recess wall 317 and the drive wheel 16.

in the event that a counterclockwise control (not shown) as substituted for the rotary control 26, the indicator strip 18 is removed from its keyed engagement with drive wheel slot 56 and engaged in drive wheel slot 50. At such time the strip is wrapped in the opposite direction about the peripheral edge of the drive wheel 16, and its indicating end is protruded through communicating area 52 into the alternative or counterclockwise indicating path 46 as denoted by partial chain outline 72 of the indicator 10. The indicator 72, then, will properly denote increasing scale indicia for counterclockwise movement of a rotary control (not shown) associated with the indicating mechanism 10 (dashed arrow 74). As noted previously the indicia 60 and a suitable slot or

window

45 or 49 can be formed on the opaque overlay plate 53 (FIG. 2).

Referring now to FIGS. 6-8 another arrangement 80 of my indicator mechanism is shown for the purpose of translating rotary movement ofa control device into movement along an external arcuate path for indicating purposes. In this arrangement the indicating mechanism 80 has a support 81 including a generally circular base member 02 having in this example a central aperture 0% and path defining wall sections 06, 08. The base member 02 is also provided with securance studs the purpose and function of which have been described previously. The central aperture 84 of the base member 02 affords passage of a control shaft and control knob extension for a suitable rotary control mechanism 26 (FIG. 53).

The inner wall section 86 additionally defines a generally cireuiar recess 90 in which is mounted drive wheel 92. The drive wheel 92 is provided with a generally central recess 94 including key 96 for keying engagement with a control knob extension 00 (FlGS. 6 and 6A) of control knob 99.

The drive member 92 is provided with strip slot 100 having a keying configuration and into which a similarly shaped end portion 102 of a flexible indicator strip 10 is inserted for securance to the drive member 92.

The wall sections 86, 00 define a generally arcuate indicator path 106 therebetween which is further enclosed by the ad jacent surfaces of the base member 82 and a cover plate 108 (F168. 7 and 8). The indicator path 106 communicates at the area denoted generally by reference character 110 with the drive member recess 90. Accordingly indicator strip 104 extends from its connection with and partial wrapping about the drive member 92 through the communicating area 110 and thence along the indicator path 106.

in the arrangement shown in FIG. 6A the drive member 92 has been rotated (arrow 112) in the clockwise direction to a point corresponding to its maximum setting. As a result the indicating end 47 of the indicator strip 10 1 is at the high end of the scale indicia denoted by reference character 114 (FIG. 7).

At this point motion of the indicator mechanism 80 can be delimited by engagement of the indicator end 47' with stop 115 at the maximum end of the indicator path 106 after the manner of FIG. 5. In many cases it is preferable to delimit movement of the indicator mechanism 00 in the maximum direction short of the stop 115 by disposing the wall end 12% and the driving wheel projection 117 to bearingly engage the adjacent portion of the strip 10d to prevent further movement of the drive wheel 92 and associated components. The strip 104 is not sufficiently resilient as to be forced into an S-bend by such engagement and to allow continued movement of the drive wheel 92. Naturally, both of these stop means can be employed in concert to ensure stoppage of further drive wheel rotation.

The scale indicia 11d and if desired an indicator slot corresponding to window 116 can be formed directly upon the front cover plate 108. Desirably, however, the front cover plate is made from a transparent plastic material, and a separate relatively thin, opaque indicia plate 110 is secured between the cover plate and the base member 82. This facilitates provision of differing scale indicia for various applications. If desired, the indicia plate can be likewise fabricated from a transparent plastic material and provided with an opaque coating save for the window area 116. The indicia plate 110 and the cover plate 100 are provided with

central apertures

120, 122 for passage of an operating shaft or control knob extension 90.

Referring again to FIGS. 6 and 6A, it will be seen that the flexible indicator strip 104 proceeds along a smooth curve or arcuate path from its connection with the drive member 92 and along the generally spiral indicating path 106. Desirably the initial portion of the path 106 is conformed to an Archimedes or similar type curve for this purpose. In furtherance of this purpose the adjacent surfaces of the

wall sections

86, 80 are given a similar configuration. The drive member 92 desirably is provided with a similar Archimedes curve section 107 to facilitate paying 011 the strip 104 along a relatively smooth curved path and particularly to avoid bending the strip 104 over the adjacent end of wall section 06, except as noted above.

Likewise, a portion 105 of the recess side of the inner wall 86 and the adjacent edge 107 of the drive wheel 92 are similarly and complementarily configured to follow the aforesaid Archimedes or spiral curve. The remaining

portions

109, 111 of the wall 86 and drive wheel 92, in this example, are of circular contour. When the drive wheel is moved to its minimum position (FIG? 6) the strip 104 becomes bound between the

surfaces

109, 111 to prevent further movement of the drive wheel 92 and to delimit correspondingly the minimum setting of control knob 90 and the rotary control attached thereto. At this point the indicating end 47' of the strip 104 is at the minimum end of slot 116 (FIGS. 6A and 7).

With the arrangement of FIGS. 6& it is possible to group the pertinent scale indicia, such as the indicia 114, generally to one side of the operating knob (such as knob 38 of FIG. 2) and to dispense with the customary pointer or other indicator affixed to the knob. With this arrangement, as better shown in FIG. 6, the scale 114 can be more easily and accurately read. In the embodiments shown, the indicia portion of the path 106 is generally circular about a point substantially concentric with that of the operating shaft 90, while the preliminary portion 124 of the indicator path 106 conforms to an Archimedes curve or spiral portion as noted above. it will be understood, of course, that any smoothly curving configuration can be employed between the indicia portion of the path 106 and the transfer or communicating area 110. Obviously, too, the indicia portion can conform to a path having a shape other than circular.

The indicating direction of the indicator mechanism d0 can be relatively reversed simply by reversing the drive member 02 on the shaft or extension 98, by similarly reversing overlay 118 if used, and by providing a base member 82 having relatively reversed wall sections 86, 0d. The latter can be accomplished simply by turning over the die plate or the like (not shown) used in molding the base member 82.

Desirably the overlay plate 110 is provided with a symmetrically disposed locating notch for cooperation with locating tab 132 on the path defining plate 82. Desirably, the indicia plate 110 is placed between the cover plate 100 and the path defining member 02 where the indicia plate is further positioned and confined by rim 13 i forming part of the cover plate 100. In this example, the cover plate rim 13 1 is fitted closely about the outer surface 130 of the outer path defining wall 8%, which can be made circular for this purpose.

From the foregoing it will be apparent that novel and efficient forms of Indicator Mechanisms have been described herein. While 1' have shown and described certain presently preferred embodiments of the invention and have illustrated presently preferred methods of practicing the same, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the spirit and scope of my disclosure.

I claim:

1. An indicating mechanism comprising a support, means on said support for defining an indicator hollow path means and a drive member recess, said path means communicating with said recess, a drive member rotatably mounted within said recess, an elongated flexible indicator joined to said drive member and extending from said recess into and along said path means, said drive member being of discoidal configuration, said indicator being at least partially wrapped about the peripheral edge thereof, said indicator being positioned on said edge solely by the adjacent surfaces of said support and said defining means and the adjacent end portion of said path means, and said support including a cover having visual access means therein aligned with at least a portion of said path means.

2. The combination according to claim 1 wherein said means are provided for detachably joining said indicator to saiddrive member, said drive member joining means extending generally in the direction of said path means so that said indicator can be detachably joined to said drive member without substantial bending.

3. The combination according to claim 1 wherein said support includes a transparent cover and a base member, said base member having said defining means thereon, and a detachable overlay indicia plate is sandwiched between said cover and said base member, said overlay plate having visual access means generally aligned with at least a portion of said path means.

4. The combination according to claim 1 wherein portions of said defining means and of said drive member are disposed respectively to bearingly engage portions of said indicator to provide stops for respectively delimiting movement of said drive member and of a rotary control coupled thereto.

5. The combination according to claim 1 including a control knob for a rotary control mounted on said support and secured to said drive member for rotation therewith, means on said knob and said control for keying said knob to said control for rotation therewith, said control being mounted on an external support member, and means for mounting said support on said support member so that said knob is maintained in keyed engagement with said control. I

6. The combination according to claim 1 wherein said path means include an arcuate path spacedly and at least partially surrounding drive member.

7. The combination according to claim 6 wherein at least the initial portion of said path is a spiral section and a portion of said drive member is similarly shaped.

8. The combination according to claim 7 wherein said spiral section conforms to an Archimedes curve.

9. An indicating mechanism comprising a support, means on said support for defining an indicator path means and a drive member recess, said path means communicating with said recess, a drive member rotatably mounted within said recess, and an elongated flexible indicator joined to said drive member and at least partially wrapped thereabout, said indicator extending from said recess into and along said path means, said path means including a pair of indicating paths adjoined with said recess at locations remote from one another to provide indications of increasing function for a preselected one of clockwise and counterclockwise movements of said drive member.

10. The combination according to claim 9 wherein scale indicia are secured to said support and disposed generally along said path means.

11. The combination according to claim 9 wherein said support is provided with visual access means corresponding to at leasta ortion of said path means.

12. e combination according to claim 9 wherein said drive member is provided with dual connection means for said indicator corresponding respectively to the relative locations of said paths to facilitate changing of said indicator from one path to another.

13. The combination according to claim 9 wherein means are provided for detachably joining said indicator to said drive member, said joining means extending generally in the direction of said path means so that said indicator can be detachably joined to said drive member without substantial bending.

14. The combination according to claim 9 wherein said support includes a transparent cover and a base member, said base member having said defining means thereon, and a detachable overlay indicia plate is sandwiched between said cover plate and said base member, said overlay plate having visual access means generally aligned with at least a portion of said path means.

15. The combination according to claim 9 wherein portions of said defining means and of said drive member are disposed respectively to engage bearingly portions of said indicator to provide stops for respectively delimiting movements of said drive member and of a rotary control coupled thereto.

16. The combination according to claim 9 including a control knob, a rotary control mechanism, said knob being secured to said drive member for rotation therewith, means on said knob and said control for keying said knob to said control for rotation therewith, said control being mounted on an external support member, and means for mounting said support on said support member so that said knob is maintained in keyed engagement with said control.

Claims

2. The combination according to claim 1 wherein said meanS are provided for detachably joining said indicator to said drive member, said drive member joining means extending generally in the direction of said path means so that said indicator can be detachably joined to said drive member without substantial bending.

5. The combination according to claim 1 including a control knob for a rotary control mounted on said support and secured to said drive member for rotation therewith, means on said knob and said control for keying said knob to said control for rotation therewith, said control being mounted on an external support member, and means for mounting said support on said support member so that said knob is maintained in keyed engagement with said control.

11. The combination according to claim 9 wherein said support is provided with visual access means corresponding to at least a portion of said path means.

12. The combination according to claim 9 wherein said drive member is provided with dual connection means for said indicator corresponding respectively to the relative locations of said paths to facilitate changing of said indicator from one path to another.