Bear is BR Hymek diesel
Bear is one of the more polite, charming, respectful, useful diesels. He is a loyal, friendly, and sympathetic sort, but he is extremely noisy and obstreperous, as he often makes unusual growling noises much to the disturbance of the other engines; thus earning the name "Bear". The Fat Controller was impressed with BoCo and Bear; he called them "versatile" because they could pull both coaches and trucks. BoCo and Bear usually defend the steam engines when a visiting diesel boasts about how superior they are, and vice versa, as the steam engines often use BoCo and Bear as examples of diesels that are not rude and nasty.
Bears is based on the British Railways Class 35 "Hymek" Diesel Locomotive. Designed for use on the Western Region of BR, 101 of these units were built between 1961 and 1964 by Beyer, Peacock and Company. The locomotives were given the nickname "Hymeks" because of the Mekydro-Design Hydraulic transition units. The Class was withdrawn between 1971-1975, with 4 members surviving into preservation.
Connor is also another member of this class.