Patent ID: 7667187

Claim:
A hollow-shaft encoder ( 1 ) and motor-shaft protective cap ( 2 ), which are repeatedly releasable from and connectable to each other by means of connection means ( 3 ), said encoder ( 1 ) incorporating all electrical and mechanical components for a pick-up and output of measuring signals and the protective cap having none of the electrical or mechanical components for the pick-up and output; wherein the encoder is housed in a casing; wherein the connection means ( 3 ) are integrated in the encoder ( 1 ) and protective cap ( 2 ) and form a connection between the encoder ( 1 ) and protective cap ( 2 ); wherein the protective cap ( 2 ) is conical and tapers away from the hollow-shaft encoder ( 1 ); wherein the encoder has first wings ( 8 ) which extend inward from the periphery of a first end of the encoder casing and the protective cap has an annular transition region ( 28 ) that extends outward from the periphery of a first end of the protective can and second wings ( 11 ) which extend outward from the periphery of the annular transition region; wherein the first and second wings constitutes the connection means ( 3 ); wherein the first end of the encoder casing includes a depression ( 7 ) formed by widened regions ( 9 ), said widened regions extending radially inward from the inner periphery of the encoder casing and spaced from the first end of the encoder casing, the first wings being incorporated in the depression; wherein a portion of the first end of the protective cap and the second wings extend into the depression, the second wings extend under and engage the first wings when rotated in an assembled position so as to prevent the protective cap from being pulled off the encoder in the axial direction; wherein the annular transition region includes an annular groove and a sealing ring situated in the annular groove and contacting a portion of the encoder casing when the protective cap is engaged with the encoder casing; wherein the encoder is accommodated at least partially in an axial recess in the protective cap; and wherein means to accommodate a tool to remove the protective cap from the encoder is fixed on a second end of the protective cap.