Flat body specialization and modularization of production and Assembly precision, interchangeable; Only one repair car cathodic electrophoresis process for structural components, effective protection of corrosion resistance; Tilt cylinder arrangement on the girders and support on the beams of the same on the inside, even distribution of load, greatly improving the service life of the vehicle; After replaceable friction plate, rollers, panels slide smoother and easy low cost maintenance; An adjustable mechanical stop device, flat lock even more accurate, more reliable and more secure; Beams and collapsed at the end of the Board hinge beam hardening, load capacity to further enhance; New bi-directional Panel, easy operation, high reliability; A variety of bundled tools, using simple jobs easier.