The oil-sprung legs of retractable landing gear are still called "Oleo struts". An oleo strut absorbs this energy, reducing bounce. The aircraft uses oleo strut suspension for its 24 wheels. Each main wheel was inboard of its gear leg and oleo. The units are fitted with large round oleo buffers, and have no gangways between carriages. The last development version of Oleo, 1.99.16, was released in 2001. The newly designed oleo attachment bracket is made of steel. Each main unit comprised two oleo legs and a single wheel.