A top cross-member is coupled to the first and second fixed panels adjacent the top edge.

The upper cross member has a mounting surface extending the length thereof.

The frame top includes an upper cross-member and two lateral reinforcement plates.

A gap should always remain between the decking (16) and upper cross member (12).

A bottom cross-member is spaced from the top cross-member and is coupled to the first and second fixed panels adjacent the bottom edge.

The bores are transversely spaced apart at a distance larger than the diameter of the medullary nail (3).

The optical aperture blocks the optical field in such a manner that it eliminates higher transverse mode lasing.

The upper cross-sectional profile (11a) and the under cross-sectional profile (11b) change extension direction either continuously or in steps that are smaller than 90 degrees.

Preferably, the upper transversal link, which is disposed on the body side, comprises a solid rotational axis (8) and the lower transversal link plane is made of three independent transversal swinging arms (3a, 3b, 3c,).

Both ends of the upper transversal tube (3) are respectively connected to the upper connection tubes (6).

Attached to the upper and lower ends of the upright member (11) are horizontal members including an upper cross member (12).

The one-piece seat back frame includes a first side member and a second side member spaced apart from the first side member, an upper cross member and a lower cross member.

A bearer beam (20) is secured to the upper transverse support (21) and wheels (19) to the lower support (16).

An upper transverse element (46) engages the tops of the vertical elements (43) and a lower transverse element (46) similarly engages the bottoms of the vertical elements.

A left support (14) and a right support (14) of the lifting device are provided with a rotary upper cross lintel shaft (8) respectively.