Section 616. Transportation of Explosives, Detonators, Conveyors, etc., Forbidden.--Neither explosives nor detonators shall be transported on flight or shaking conveyors, scrapers, mechanical loading machines, locomotives, cutting machines, drill trucks, or any self-propelled mobile equipment: Provided, however, That this does not prohibit the transportation of explosives or detonators in equipment designed especially to transport such explosives or detonators.