page_title: Bo-Bo
section_title: 1A-A1 (or A1-1A)
hierarchical_section_title: Bo-Bo / B′B′ / 1A-A1 (or A1-1A)
caption_attribution_description: British Railways mixed three-car diesel-mechanical multiple unit formed of Derby Works class 107 driving motor composite lavatory number SC52035 and trailer second lavatory number SC59787 and Metropolitan-Cammell Railway Carriage &amp; Wagon Company Limited class 101 driving motor brake second number SC51469 stands inside Ayr Traction Maintenance Depot during the Railfair open day. Sunday 30th October 1983
context_page_description: B-B and Bo-Bo are the Association of American Railroads and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies. They are equivalent to the B′B′ and Bo′Bo′ classifications in the UIC system. The arrangement of two, two-axled, bogies is a common wheel arrangement for modern electric and diesel locomotives.
context_section_description: Railcars and multiple units use similar two-axle powered bogies and many of them use similar hydraulic or mechanical transmissions, rather than traction motors. However railcars are also lightweight and do not require all axles to be powered in order to gain adequate adhesion. They thus use a wheel arrangement of 1A-A1 (UIC: (1A)(A1) ) (or A1-1A (UIC: (A1)(1A) ) ) rather than B-B. A common arrangement is for each power car to have two independent engines and transmissions, each driving a single axle of each bogie.
  The difference between 1A-A1 and A1-1A is that 1A-A1 has the powered axles being the axles furthest from the ends, whilst A1-1A has the powered axles closest to the ends.
caption: BR class 107 multiple unit
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