Contact Meter

an instrument for measurements of the pressure (or contact) line in wide cylindrical spiral gears having an involute profile. The pressure line is located at the intersection of the side surface of a tooth with a plane tangent to the base circle. It is characterized by its shape (straightness) and by its location with respect to the gear axis (the pressure angle). A distinction is made among all-purpose contact meters, which are used to check the direction and straightness of the pressure line; contact meters designed only to check straightness; and contact meters used only to check direction. The main subassemblies of a contact meter are the device for centering the contact meter or the gear, a unit used in adjusting for the location of the pressure line, a measuring mechanism (with a probe tip), and a recording or reading device. The tip of a contact meter passes through all points of the pressure line and determines its deflections, which are then registered by the recording or indicating device.