Universal joint wear indicator

An end of life indicator for a universal joint comprises an indicator member that monitors the temperature of the cross member of the universal joint. As the universal joint approaches the end of its life, the cross member exceeds expected temperatures as the bearings begin to wear. At a temperature above the typical operational temperature expected with a properly functioning universal joint, but below the temperature wherein the universal joint could be damaged or seize, a portion of the temperature indicator melts allowing the indicator to move to the actuated position. An operator will be able to visually identify the universal joint as approaching the end of its life. In one preferred embodiment, the indicator includes a plug at a position spaced forwardly of the indicator piston, with the plug holding the piston at the non-actuated position. When the plug melts, the indicator is spring biased to an outwardly actuated position where the operator will be able to visually identify an actuated indicator.