Control mechanism

Claim 1

Control mechanism for the advance and withdrawal of a functional part displaceable in a housing against or under the influence of a spring, and for locking the said part in advanced and withdrawn positions, such mechanism comprising a pressure actuating member which is displaceably mounted in said housing and has a central axis extending in the direction in which the member is displaceable; an actuating end to said pressure actuating member extending out of the housing; control elements provided on said pressure actuating member, such control elements being arranged at the same height relatively to said central axis of the pressure actuating member and projecting radially from the pressure actuating member, the control elements having a ''''near'''' and ''''remote'''' end relatively to said actuating end of the pressure actuating member; at least one control face provided at the remote end of the control elements and designed as a bevelled face whicH extends in the direction of a tangent to a circle, the centre of which is located on the said central axis of the pressure actuating member; strip-shaped projections formed internally on said housing and extending, in spaced relationship, parallel to the said central axis of the pressure actuating member with said control elements engaging in the spaces between the strip-shaped projections; a bevelled control face at the ends of said strip-shaped projections remote from the actuating end of the pressure actuating member, such bevelled control face extending in the same direction as the control face of the control elements of the pressure actuating member; guide faces at the longitudinal sides of said strip-shaped projections and on which the control elements are so guided over their entire displacement that the pressure actuating member is secured against rotation, the control faces being located at the same height relatively to the said central axis; a control member which is rotatable in the housing and displaceable in the direction of the said central axis of the pressure actuating member; control elements provided, in spaced relationship, on said control member and projecting radially therefrom, such control elements, as seen from the actuating end of the pressure actuating member, being arranged behind the control elements of the pressure actuating member and being disposed at the same height relatively to the said central axis, and having, on the sides thereof facing the control faces of the control elements of the actuating member, in each case a notch into which, in the advanced position, the end carrying the control face of a stripshaped projection engages; at least one bevelled control face on each notch co-operating with the control faces of the pressure actuating member and of said strip-shaped projections and extending in the same direction as the latter, the spacing between the control elements of the rotatable control member being so dimensioned that the said strip-shaped projections are able to travel between the control elements; a stop formed between the said strip-shaped projections internally of the housing for the control elements of the rotatable control member travelling, on transition from the said advanced position into the said withdrawn position, into the interspaces between the strip-shaped projection; and a spring arranged in the housing and acting on the rotatable control member in such a manner that the control faces thereof, on the advance of the pressure actuating member, are pressed against the control faces of the latter and, on withdrawal of the pressure actuating member, are pressed against the control faces of the strip-shaped projections, whereby, due to the pressure of the control faces of the rotatable control member against the control faces of the further mechanism parts, further-rotation of the rotatable control member is achieved.