The resistances used by the tractioin control equipment were located under the floor behind the cab. The covers over the top would provide a certain amount of physical protection whilst the vehicle was a bare chassis but I suspect their main role was as a fire barrier - resistances can get quite hot!
Photograph from the GEC archive
Categories & Keywords
Category:Transportation
Subcategory:Buses
Subcategory Detail:
Keywords:BUT, City of Cardiff, GEC, trolleybus, 9641T