GB1005188A - Improvements relating to flying helmets - Google Patents

Abstract

1,005,188. Respiratory helmets. M. L. AVIATION CO. Ltd. March 9, 1962 [March 14, 1961], No. 9316/61. Heading A5T. [Also in Divisions A3 and G2] A pressurised helmet has an open front and a pivoted lune-shaped visor 10 which when not closing the opening is stored within the helmet, a pressure-tight hood 36 being sealed along the upper edge of the visor, round the visor pivots 48, and to the helmet so that when the visor is open the hood is folded behind it and when the visor is closed the hood forms a pressure-tight seal between the upper edge of the visor and the helmet. The hood is also lune-shaped and, when the visor is open, is stored with the visor in a lune-shaped compartment 28 at the top of the helmet. The sides 56 of the hood are concave and have an enlarged rim which is continuous with a seal 16 along the lower edge of the visor between parallel transparent plates 11, 12 forming the visor. The rim 54 at each side of the hood is slidable in spiral grooves in bosses fixed to the helmet around the pivot shafts 48, the grooves being narrower towards the front so that the rim is compressed when the visor is closed to form a seal. The sides of the visor are fixed to side plates 42, pivoted on the shafts 48, each side plate having an extension 57 on the opposite side of the pivot. The visor is urged into closed position by a tension spring 60 which extends around the back of the helmet between the two side plate extensions. The visor is held in open position against the spring by the free end of a lever 61 which bears against one of the side plate extensions 57 and is pivoted on the helmet shell. An operating bar 65 which extends around the outside of the helmet is connected to sleeves 66, rotatable on the pivot shafts 48. At one side a sleeve 68 is connected to a plate 69 pivotal about the shaft 48 and having a cam surface 70 which bears against a roller 63 on the lever 61. On manually pivoting the operating bar downwardly the cam surface moves the lever out of contact with the visor side plate extension 57 so that the visor closes. In its lower-most position, the operating bar secures catches which hold the visor closed. The lever 61 is also connected by a linkage with a lever 78 which normally bears against a head 77 connected to a barometric capsule 71 on the exterior of the helmet. If the pressure outside the helmet falls unduly, the head is moved by the capsule out of engagement with the lever 78 thus allowing the linkage to move so that the lever 61 disengages the visor side plate extension and the visor closes. Also the lever 61 may be disengaged from the extension on expansion of a bellows 112 which is connected with bladders mounted inside the helmet opening. The bladders collapse to expand the bellows if they are subjected to a sudden increase in pressure e.g. due to an explosion. The helmet has a sun visor 128 which is normally housed in the compartment 28 and may be pivoted on the shafts 48, 49 by a handle 130 to a position over the eyes of the wearer. An oxygen mask 4 having a door 20 through which the wearer may feed himself is located inside the helmet. Specifications 941, 494, 1, 005, 186 and 1, 005, 187 are referred to.