The Building Maintenance Unit (BMU) is a system with telescopic jibs for all cleaning and maintenance on buildings. The cradle is designed to take one or two people together with their tools and cleaning materials. building maintenance unit (BMU) is an automatic, remote-controlled, or mechanical device, usually suspended from the roof, which moves systematically over some surface of a structure while carrying human window washers or mechanical robots to maintain or clean the covered surfaces. BMUs are almost always positioned over the exterior of a structure, but can also be used on interior surfaces such as large ceilings (e.g. in stadiums or train stations) or atrium walls. The BMU type S, T are systems with telescopic jibs for all cleaning and maintenance on buildings. The cradle is designed to take one or two people together with their tools and cleaning materials.