Rotational frequency sensing device with pulse generating wheel having two-axial position supporting sleeve

A rotational frequency sensing device for a machine element rotatable about an axis, said device comprising a pulse generating wheel and a radial shaft sealing ring;

• wherein the pulse generating wheel has a cylindrical sleeve that is slid onto the machine element;
• wherein the radial shaft sealing ring is provided with a sealing lip made of polymer material, the sealing lip having a radially inwardly directed conical surface;
• wherein the cylindrical sleeve has a first axial position and a second axial position;
• wherein in the first axial position of the cylindrical sleeve, the conical surface is contacted by the cylindrical sleeve and is expanded in the radial direction;
• and
• wherein in the second axial position of the cylindrical sleeve, the cylindrical sleeve is at an axial distance from the conical surface and the sealing lip is in direct contact with the machine element.