The AVW DUAL Z-WRAP MITTER COMBO operate on gravity.No complicated controls because of the design it can self adjust to most conveyor speed requirements. Simple design and low maintenance. The mitter curtain has a unique basket motion that provides aggressive motion on the vehicle surface not just atthe top of the basket. It is constructed of high grade stainless steel. Telescopic height adjustment allows for easy installation even in settings with limited or obstructed heights. There are no bearings to grease on this unit.