The type MB 50 is the most universal self-tensioning base for all friction belt drives with 5.5 to 45 kW electric motors (frame size dimensions 132 S to 225 M). The standardized base plate can be installed on the rubber spring either "center" or "off-set" according to the position of the driven pulley. The pretensioning device can be attached in 3 different positions allowing to incline the base plate according to the ideal working angle. The belt pretension can be continuously settled equivalent to the belt size and quantity . The ROSTA motorbase type MB 50 is supplied disassembled in different kits; all steel parts are painted with a blue primer.