Step switching mechanism switchable forward and backward
United States Patent [1 1 [111 3,876,848  
 Hartmann 1 Apr. 8, 1975 1 STEP SWITCHING MECHANISM SWITCHABLE FORWARD AND BACKWARD Inventor: Fritz Hartmann, 1m Heuschlag 9,  
 852 Erlangen, Germany Filed: Jan. 31, 1974 Appl. No.: 438,470  
 References Cited UNITED STATES PATENTS 4/1972 Jordan et a1. 200/156 FOREIGN PATENTS OR APPLICATIONS 1,110,276 7/1961 Germany 200/156 Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney, Agent, or Firm-Robert H. Jacob [57] ABSTRACT A step switch mechanism operable in both forward and reverse directions has a common feeler for both directions. The feeler is tiltable toward the desired direction and simultaneously slidable transversely to the direct of operation.  
 6 Claims, 4 Drawing Figures STEP SWITCHING MECHANISM SWITCHABLE FORWARD AND BACKWARD The invention concerns a step switching mechanism that can be operated in forward and reverse directions. It already has been proposed in connection with such a step switching mechanism to provide a common feeler for both directions of movement which, depending on the desired direction of operation, is tiltable to ward the desired direction of operation of its position of rest in one direction or the other and simultaneously slidable transversely to the direction of operation. In this connection the feeler acts on operating stepping means of a driven part in the existing direction of operation and is tiltable to both sides in a sliding guide and displaceably supported obliquely to the direction of operation. A spring supported against the housing counteracts its displacement in the longitudinal direction in the guide.  
  Step switching mechanisms of this type can serve in connection with switches and leads as coding switches, for example for decimal or binary code systems.  
  In the proposed step switching mechanism the further switching of the driven part takes place in two distinctly separated half steps. The actuating feeler path has a break, so that there is danger that the operator may release the feeler button after a half step, which can result in faulty switching.  
  The invention is based on the problem of equipping a step switching mechanism of the proposed type in such a manner that a short sensing path is provided owing to which the measure of division can be selected to be very small, and rapid setting is made possible and the sensing path extends continuously.  
  In accordance with the invention this problem is solved in the forward and backward switchable step switching mechanism described above in that the sensor is constructed in one piece with a feeder button for each direction of movement of the connection of the scanning buttons has a small resilient bridge, that two stationary abutment studs are provided, one of each of which cooperates with a coordinated oblique edge of the feeler, and that the feeler has two transport studs symmetrical with the longitudinal axis and a transport wedge in the longitudinal axis which cooperate with a star-shaped sprocket wheel of the driven part.  
  By means of the invention a step switching mechanism is provided which consists essentially of merely three parts, which can be set rapidly and easily without danger of faulty switching.  
  It is particularly suitable when the transport wedge is constructed as border limit of the guiding slide.  
  In the preferred embodiment of the invention the guiding slide consists of a longitudinal slot having oblique sliding surfaces in the feeler and a securing stud fixed on the housing.  
  Advantageously the transport studs are each provided with a cutter-like edge whose flanks are facing one another and are longer than the outer flanks.  
 In a preferred embodiment of the invention the FIG. 1, a longitudinal section through a step switching mechanism in accordance with the invention,  
  FIG. 2, a plan view of an opened step switching mechanism,  
 FIG. 3, a digit wheel as a driven part, and  
 FIG. 4, a feeler as driving part.  
  In a housing 1 having a window cutout 1a, a fixed axis lb for a digit wheel 2 is provided with a suitable bore. Furthermore a right abutment stud 1d is in the bottom of the housing 1, and a left abutment stud 1e as well as a rearward fixing stud 1c are formed. The housing furthermore has a right cutout 1f in its forward wall for a feeler and a left cutout 1g for a second feeler.  
  In the embodiment illustrated a digit wheel 2 serves as driven part with a wheel mantle 2a and a star-shaped sprocket wheel 2b serving as switching or advancing member. A free space 20 is provided for a contact device.  
  In the housing 1 a sensor 3 is longitudinally slidable and disposed somewhat tiltably in two directions. The feeler 3 has two limiting ribs 31&#39; for a pressure spring 4 which supports itself against the rear wall of the housing 1 and counteracts any longitudinal displacement of the feeler 3, so that the pressure spring 2 also applies a resetting force after the feeler actuation has taken place.  
  For each direction of movement of the driven part 2 a feeler knob is provided, which in the drawing are illustrated as right feeler knob 3a and left feeler knob 3b. The feeler knobs 3a and 3b are made to constitute a unitary member with the remaining feeler 3 and are connected with the main part by way of resilient parts 32 and 32. The narrowing in the area of the resilient parts 3e and 3e is formed by one each cutout which merge into an oblique abutment or sliding surface 3/1, 3/1. Abutment studs 1d and 1e fixed to the housing are associated with these sliding surfaces 311 and 3/1. In the forward area transport studs 30 and 3d are arranged on the feeler which are provided with a cutting edge 30c or 3a&#39;d. These cutting edges 3cc and 3dd cooperate with the teeth 2b of the star-shaped sprocket wheel 2b.  
  In the rearward area the feeler 3 extends through a sliding guide which consists of a cutout 3g for a fixing stud 10 that is secured to the housing and an oblique sliding surface 3g. The forward limit of the cutout 3g is defined by a transport wedge 3f with a cutting edge 3f, each of which cooperates with the cutout between two teeth of the star-shaped sprocket wheel 2.  
  In the position of rest the feeler 3 is disposed symmetrically in housing 1, the feeler knobs 3a and 3b are guided in the housing cutouts lfand 1g, and in the cutout 3g extends the securing stud 1c. The digit wheel 2 is journalled by means of its central bore on the axis lb stationary in the housing. The transport wedge 3f is pressed by pressure spring 4 against the toothed crown 2b and effects a fixed angular position of the digit wheel 2.  
  On pressing a feeler knob, for example 3a, a pressure is applied against pressure spring 4 that is disposed against the direction of pressure. The feeler 3 rocks during the first phase in clockwise direction until the abutment and sliding surface 311 contacts the abutment stud 1d. The resilient part 3e makes possible the rocking of the feeler 3. The cutting edge 3cc of the transport stud 3c has been moved laterally to the tooth point 2b. In the second phase the feeler 3 slides with its oblique sliding surface 3h against the abutment stud 1d and with its sliding surface 3g against the fixing stud 1c in the direction of the pressure spring 4. Thus the transport wedge 3freleases the toothed crown 2b, the transport stud 3c enters with its cutting edge 30c laterally of the tooth point 2b and turns the digit wheel 2 by onehalf toothed portion in counterclockwise direction. The oblique arrangement of the sliding surface 311 thereby effects that the toothed crown 2b comes to rest with the tooth point 2b exactly on the horizontal center line, respectively the longitudinal axis. This is a prerequisite for the further transporting operation. Now the transport step has been half completed. When the feeler knob 3a is now freed, the pressure spring 4 presses the feeler 3 again into its starting position, re-  
 spectively its position of rest. The transport wedge 3f that is disposed laterally of the tooth point 2b owing to the oblique arrangement of the sliding surface 3g engages in such a manner that the digit wheel is turned in counterclockwise direction until the corresponding switch rest position has been fully reached.  
  The left half of the feeler and of the housing are symmetrically constructed, so that on operating the left feeler knob 3b the digit wheel 2 is turned further in clockwise direction in an analogical manner.  
  The housing 1 may be covered in a manner known per se and not shown, and may, if necessary, be provided with a printed circuit whereby the closure plate has a border extending above the housing which carries the outer contacts or connections.  
  The digit wheel 2 has numerals or other symbols which can be seen in the window cutout la provided at the operating side of the housing 1.  
  A step switching mechanism in accordance with the invention may also be produced with very small dimensions where the numberings on the digit wheel are relatively large. For this purpose the construction is such that in a known manner several step switching mechanisms are disposed alongside one another or above one another and can be connected with each other.  
  Thus, the invention is not limited to the embodiment illustrated and described. It encompasses also all professional modifications as well as all parts and subcombinations of the described and/or illustrated features or measures.  
  Having now described my invention with reference to the embodiment illustrated in the drawings, what l desire to protect by letters patent of the United States is set forth in the appended claims.  
 I claim:  
  1. Forward and backward switchable step switching mechanism comprising a feeler common to both directions of operation tiltable from a position of rest in one direction or the other and simultaneously slidable transversely to the direction of operation, and including a driven part having switching means acted upon in the existing direction of operation, sliding guide means supporting said feeler for tilting movements in opposite directions and for sliding movements transversely of the direction of operation, a spring biasing said feeler in said housing against longitudinal displacement, said feeler having one each unitary knob for each direction of movement and one each resilient bridge for connecting said feeler knobs with said feeler, two stationary abutment studs being provided, said feeler having 0blique edges, one each cooperating with an abutment stud and having two transport studs extending symmetrically to the longitudinal axis and having a feeding wedge disposed along the longitudinal axis proximate said driven part.  
  2. Step switching mechanism in accordance with claim 1 where said feeding wedge is the border limit of said sliding guide means.  
  3. Step switching mechanism in accordance with claim 2, where said sliding guide means is defined by an elongated slot having oblique sliding surfaces on said feeler and a stationary stud.  
  4. Step switching mechanism in accordance with claim 1 where said transport studs each present an edge having opposite flanks that are no longer than the outer flanks.  
  5. Step switching mechanism in accordance with claim 1 having a driven member defining a digit roller or the like and said housing having a fixed axis encompassed by said feeler.  
  6. Step switching mechanism in accordance with claim 5 where all components excepting the spring are made of plastic material.  
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