GB815498A - Improvements relating to pressure helmets breathing masks and the like - Google Patents

Abstract

815,498. Respiratory appliances. TAYLOR, E. H., and BAXTER WOODHOUSE & TAYLOR Ltd. June 1, 1955 [March 12, 1954], No. 7280/54. Class 81 (2). In a pressure helmet a vizor is mounted for movement into and out of sealing engagement with an aperture opposite the eyes. In opening, the first movement of the vizor is forwardly away from the helmet to break the seal and the second movement is upwardly away from the opening. As shown, Fig. 1, the wearer moves the vizor bar 5 up or down in order to open or close the vizor 2, which in the closed position, fills the opening 4. Sealing is effected between 2 and the shell 1 by the deflatable means 16. A sun vizor 6 is movable independently, between 2 and 5. The helmet consists of a fibre front 1 which curves toward the front and top of the head and a rear part of fabric material 12 closed by a sliding fastener. Mounted on 1 are the intercommunication lead-in 8, oxygen supply pipe 11 and the emergency oxygen inlet 15. Pressurization is effected by an inflatable envelope (not shown) between 1 and 12 which envelopes the head and part of which forms the seal 16, and which includes an oxygen mask covering the nose and mouth. When 2 is closed on to a seal 16, the space in front of the. eyes can be maintained at the required pressure. Unsealing action. Movement of the bar 5 causes the vizor 2 to move about hinges 3. In one embodiment of hinge 3, Figs. 6, 7, movement of bar 5 upwards rotates shaft 29, through gearing 40, 41 and causes cranks 29 to move outward and forward thereby moving forward the vizor frame 20 away from engagement with seal 20 with further movement upwards of 5, the rotation of 29 is stopped by the engagement of the cam and stud 33, 36, a locking mechanism is released by 33 and the upward pressure on 5 carries the hinge cover 26 round the axis of spindle 25 and raises 2 above 4, against the action of the spiral spring 47. In a second embodiment, not shown, the cam and stud 33, 36 is replaced by a cam which engages with two slots in the case and base plate. In a third embodiment, Figs. 18, 19, the support rods 61 of the vizor frame 20 are urged along the slots 62 by rotation of the eccentric 53 inside the internally threaded collar 60 by the initial unsealing movement of vizor bar 5. Subsequent raising of the vizor takes place against the action of spring 70. In all the embodiments, the vizor is held in the open position by a spring catch device (not shown). Specification 815,499 is referred to.