| 摘要 |
1289768 Stand heads C O'CONNOR 10 July 1970 [17 July 1969] 33627/70 Heading A4H [Also in Division F2] An instrument panhead for a camera 12 comprises a chamber 21 ending in an annular sealing region partly defined by a pair of interconnected surfaces 41, 42 and an opposed relatively rotatable surface 43, and a unitary seal 30 of P. T. F. E. and of U-section having a pair of sealing surfaces 45, 46 in firm sealing engagement with the pair of inter-connected surfaces and a sealing surface 47 in sliding contact with the rotatable surface, the seal being resiliently deflected upon installation and formed with a surface exposed to the chamber so that a pressure differential across the seal would tend to urge the sliding surface or edge of the seal against the rotatable surface. The main body 14 of the panhead is supported for panning movement on a bearing 31 which is disposed in the chamber 21 defined by a skirt 22 depending from the main body and a pedestal 23 extending upwardly from a base 15. When the instrument is used in an area of reduced pressure as when employed in an aircraft, the effectiveness of the seal is increased to prevent the escape of the silicone fluid in the chamber 21. The panhead also includes a cylindrical portion 16 which carries an instrument platform 17 and rotates about a horizontal axis. Both the tilting and the panning movements are made in response to manual pressure on a handle 13 and the control and resistance to such movements is provided by the silicone fluid in the chamber 21 and cork-surfaced bands 24 which are tightened into frictional engagement by means of knobs 25, 26; the cork-surfaced band 24 shown is anchored to the skirt 22 and is adjustably-drawn about the pedestal 23 by the knob 25. |
