| 摘要 |
<p>1,220,618. Weapon mountings. MESSERSCHMIDT - BOLKOW - BLOHM G.m.b.H. 24 April, 1968 [25 April, 1967], No. 19386/68. Heading F3C. [Also in Divisions F2 and G2] In a rotary follow-up apparatus, viz. an apparatus such as a weapon or camera rotatably mounted so that the user can keep a line of sight trained on a moving object, the follow-up movement is damped by a frictional damper in which at least one of the frictional surfaces is of polytetrafluorethylene. At and above a critical velocity of relative movement over a P.T.F.E. surface, the coefficient of dynamic friction is substantially constant; below this velocity the coefficient rises with velocity. In the present application, the velocity will be subcritical in use, so that starting movement is not resisted but more rapid movement is damped. Fig. 1 shows the follow-up apparatus 10 rotarily mounted on a fixed support 7 by means of a bearing assembly 14. The relatively sliding surfaces 15, 17 carry respective ring inserts 16, 18, Fig. 2, which are in mutual contact and consist respectively of polished steel and P.T.F.E. The steel ring may be P.T.F.E. coated, e.g. by P.T.F.E. molecules " picked up " from the P.T.F.E. ring. The bearing. Fig. 4, is a self-adjusting cone bearing incorporating balls. In Figs. 5 and 6 (not shown), the P.T.F.E.-containing sliding bearing (34) corresponding to the sliding bearings 15, 17 of Figs. 1 and 2 is itself a selfadjusting cone bearing but without balls.</p> |
