Les:
OB was powered with steam from the locomotve pushing it. The connections and piping were stored inside the OB's structure.
You can find the complete history and technical information on Pile Driver OB in two publicatons I wrote:
NARROW GAUGE PICTORIAL: Volume 7 - Denver & Rio Grande Western Work Equipment - OA to OZ
By Jerry B. Day. Covers the specialty work equipment used by the D&RGW narrow gauge operations.
224 pages, album format, softbound. $35.00
[
www.crrm.org]
Rio Grande Modeling & Historical Society Prospector magazine, Volume 3, Number 1, available for $10.00 at:
[
www.drgw.org]
Jerry Day