Abstract: A hinge pivots a cover to a base of an object, and consists of a sleeve, an acting counteraction bar, a passive counteraction bar, and an oil hydraulic member; the acting counteraction bar has a connecting section, and a slope section, and is fitted in one end of the sleeve, and joined to the cover at the connecting section; the passive counteraction bar has a slope section, and is held in the sleeve in a linearly slidable manner with its slope section touching the slope section of the acting counteraction bar; the hydraulic member has an acting end, and is pressed against other end of the passive counteraction bar; when the cover is being pivoted open, the slope section of the acting bar will slide on the slope section of the passive bar to push the passive bar for the hydraulic member to slow down the acting bar.

Abstract: An air cylinder has a piston, an inner tube, an outer tube, a cylinder tank, a control valve, an O-ring, a bearing, and an oil seal. The inner tube is inserted in the outer tube. The outer tube is inserted through the cylinder tank. The control valve is disposed on a top end of the inner tube. The bearing is disposed on a bottom of the inner tube. The O-ring encloses the control valve. The oil seal encloses the bearing. A first sealing device is disposed between the outer tube and the control valve to separate the O-ring and the outer tube, and a second sealing device is disposed between the outer tube and the oil seal.