GB844060A - Improvements relating to head gear for airmen - Google Patents

Abstract

844,060. Respiratory appliances. M. L. AVIATION CO. Ltd. Oct. 2, 1957 [Oct. 10, 1956], No. 30892/56. Class 81(2) [Also in Group VII] An airman's helmet has a front opening 2, Fig. 1 and is fitted with a transparent visor 6 mounted on side arms 7 pivoted at 8 to the sides of the helmet so as to swing from the open position shown in Fig. 1 to a closed position in which the visor seals the opening 2. A face seal in the form of an inflatable bag (not shown) is secured to the interior of the helmet around the edge of the opening 2 so that its edge extends around the airman's face and the bag is formed with two flaps which overlap at the rear of the airman's head and serve to equalise the pressure in both directions when the bag is inflated, thus avoiding forward movement of the helmet. The arms 7 are each provided with an internal spring 21 Fig. 4, which exerts an inward bias on the visor 6 to provide effective sealing pressure against the edges of the opening 2. The visor 6 is urged to the closed position by springs encircling the pivots 8 and is held in the open position by a latch 12 which engages a trigger controlled by a barometric capsule 13. The latch 12 may be released manually or automatically by means of the capsule 13 in the event of a drop in the pressure in the aircraft cabin. Manual movement of the visor is effected by a pair of lugs 30, pivoted to a bridge piece mounted on the visor, each lug having secured to it a rod 35 which extends downwardly to the mechanism shown in Fig. 4 and which is pivotally connected to a bellcrank lever 41 pivoted on the arm 7. The mechanism is such that by squeezing together the two lugs 30, the bell crank levers 41 are rocked to cause release of the latch 12 and relief of the inward bias on the visor caused by a spring 21. While gripping the lugs 30 the airmen can than move the visor downwardly into the closed position.and when the lugs are released the inward bias is restored. Movement from the closed to open position is affected similarly. the visor 6 to provide effective sealing pressure against the edges of the opening 2. The visor 6 is urged to the closed position by springs encircling the pivots 8 and is held in the open position by a latch 12 which engages a trigger controlled by a barometric capsule 13. The latch 12 may be released manually or automatically by means of the capsule 13 in the event of a drop in the pressure in the aircraft cabin. Manual movement of the visor is effected by a pair of lugs 30, pivoted to a bridge piece mounted on the visor, each lug having secured to it a rod 35 which extends downwardly to the mechanism shown in Fig. 4 and which is pivotally connected to a bellcrank lever 41 pivoted on the arm 7. The mechanism is such that by squeezing together the two lugs 30, the bell crank levers 41 are rocked to cause release of the latch 12 and relief of the inward bias on the visor caused by a spring 21. While gripping the lugs 30 the airmen can than move the visor downwardly into the closed position.and when the lugs are released the inward bias is restored. Movement from the closed to open position is affected similarly.