| 摘要 |
<p>Different sized tubes can be accommodated in a gripping dog that consists of an outer hollow cage, the inside surface of which is divided into three equal sections which are curved from the outside towards the centre. Three rollers fastened to a cover ring are held in contact with these tapered surfaces, and ring and cage rotate concentrically to each other. When the cage is rotated, it forces the rollers inwards to grip the tube placed along the centre line and turn it the required amount. Rotation in the possible direction releases the tubes. The cage and cover ring may be moved by pressure cylinders or by springs.</p> |
