page_title: B unit
section_title: List of B unit locomotive models
hierarchical_section_title: B unit / List of B unit locomotive models
caption_attribution_description: Australian diesel locomotive (cabless slave unit) XRB 561 at the South Dynon motive power centre, Melbourne
context_page_description: A B unit, in railroad terminology, is a locomotive unit which does not have a control cab or crew compartment, and must therefore be operated in tandem with another coupled locomotive with a cab. The terms booster unit and cabless are also used. The concept is largely confined to North America. Elsewhere, locomotives without driving cabs are rare.
context_section_description: These are all known B unit models, with discrepancies settled by the later (Marre) reference. At least one of each model was manufactured. All units below contain one or more engines and traction motors, so slugs and snails are not listed.  Cow-calf units are also not listed, since these were considered a single locomotive. The New York City Revenue cars 66 and 67 were R8A units which were B units also.
caption: Australian XRB class locomotive.
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