To see a couple more: http://justacarguy.blogspot.com/2011/03/diplocks-pedrail-what-name-somebody.html
For the most thorough look at the Pedrail system: http://cyberneticzoo.com/tag/walking-wheels/
if you want to read about it http://books.google.com/books?id=63QnAAAAMAAJ&pg=PA699&dq=belgian++pipe&hl=en&ei=Xc1GTqjoCIGssQLRscSSCA&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDIQ6AEwAg#v=onepage&q=belgian%20%20pipe&f=false