A hot bearing simulator is provided for verifying the proper operation of hot box detectors in a dynamic fashion. The hot bearing simulator employs a temperature controller and heater means associated with various axles of a rolling carriage. The heaters are adjusted such that a hot box detector will be verified to determine if it is able to sense when the absolute temperature of left or right wheel bearings exceeds a first predetermined temperature or, alternatively, when the difference in temperature between a left and right wheel bearing differ by a second predetermined amount.
