Method of determining wear in a bearing surface

A method of determining an amount of wear in a spherical working surface of a bearing ring of a spherical plain bearing, the method comprising steps of:

• providing a reference groove of predetermined depth in the working surface, when the working surface is in an unworn condition;
• after a period of service, using the reference groove and axial end faces of the bearing ring as reference surfaces for centering and aligning a measuring tool, the tool having the following features:
• a first surface adapted to face the spherical working surface of the bearing ring, and a protrusion that extends from the first surface in radial direction and is adapted to fit into the reference groove;
• first and second clamping sections that engage the axial end faces of the bearing ring;
• two or more radial openings that extend from a second surface of the tool through to the first surface, and which are axially spaced from the protrusion;
• and
• measuring a radial distance with a depth gauge associated with at least one of the two or more radial openings;
• determining the amount of wear by measuring the radial distance to the spherical working surface through each of the radial openings and comparing the measured value with a reference value measured using the tool for an unworn working surface comprising a reference groove of the same predetermined depth.