Balancing device for mounting seats with variable shapes and sizes. Manipulator Partner Equo, overhead trolley mounted version equipped with pinch jaws tooling for handling and installation of bus seats with variable shapes and types. The tooling is able to grip the seats positioned flat, to tilt them by 90° with a pneumatic device and release them in a vertical position inside the bus, thanks to a telescopic arm and a particular shaping of the terminal arm. The Manipulator is supplied complete with an overhead trolley to run in a tracking system, composed of two opposite aluminium U sections with connecting and stiffening ribs,complete with attachment points for an overhead suspension and end buffers. The junction between the various parts is done with screws. More than 50.000 manipulators are in use throughout all the industrialised areas of the five continents.