Patent GB-848208-A (GB)
Title: Improvements in means for securing an occupant in a seat such as an aircraft ejection seat
IPC: B64D25/10
Filed: 1956-12-21
Abstract: 848,208. Aircraft ejection seats. MARTIN,J., and MARTIN-BAKER AIRCRAFT CO. Nov. 12, 1957 [Dec. 21, 1956], No. 38955/56. Class 4. [Also in Groups XXV and XXXIV] An aircraft ejection seat has means for coupling an occupant's main body harness to a back rest of the seat, comprising a strap connected to and wound on a drum rotatably mounted on the seat back and spring biased to wind in the strap, a link forward of the seat and securable to the harness, the strap extending forwardly from the drum to the link and back to a releasable fastening on the seat, a clamp normally engaging the strap to prevent movement thereof under a forward load but to permit the spring to wind in the strap, and means operable by the occupant to release the clamp. The fastening between the strap and seat may be released at the same point in the ejection sequence as seat harness fastenings, and all fastenings may be manually releasable. Fig. 1 shows the drum 5 mounted on a shaft 7 fixed to the seat 1 and biased by a coil spring 11 so as to tend to wind in the strap 9, which passes over fixed guide pulleys 13, 14 to a pulley 19 on the link 15 attached to the occupant's body harness 17. The strap continues to a lug 21 normally inserted in an aperture 25 in a housing 27 on the seat (see also Fig. 2) and engaged by a bolt 29 biased by a spring 31 to the lug engaging position. The bolt is chamfered so that it engages the lug on insertion of the latter into the housing. The clamp comprises a fixed plate 47 on housing 27, and a cam 49 mounted on a fixed shaft 51 and biased to grip the strap with plate 47 by a spring 75. A forward load on the strap tends to tighten the clamp, but movement of the strap under the action of spring 11 is not impeded. The surfaces of plate 47 and cam 49 may be serrated. The clamp can be released by operation of a manual lever (not shown) pulling on a cable 57 attached to a crank arm on cam 49. The cable may be replaced by suitable linkwork, see Figs. 5-7 (not shown). To free the occupant from the seat, bolt 29 may be withdrawn from lug 21 by a sear 41 acting on a roller 39 mounted in the bifurcated end 37 of the bolt. The sear is operated by a lever 83 pivoted on the seat, Fig. 8, and rotatable by a member (not shown) in a housing 87 at the appropriate point in the ejection sequence. Lever 83 is also connected by tie 83 to a rod 91 movable on parallel swing- ing links 97, 99 and bearing a sliding collar 101 pivoted to a lever 103 mounted on the seat. On rotation of lever 83 during the ejection sequence, rod 91 is moved parallel to itself and rotates lever 103, which is connected to a shaft 105, Fig. 9, running transversely of the seat. Crank arms on the shaft are connected to rods 109, 111 pivoted to bell crank levers 117, 119 operating in bolts 133, 135 similar to bolt 29. Disengagement of bolt 29 from lug 21 is thus accompanied by disengagement of bolts 133, 135 from rings on the seat harness, completely freeing the occupant from the seat. Manual disengagement at any time is possible by rotating a hand lever 165, linked to a sear 159 operating on a roller 155 mounted on a rod 151 connected to bell crank lever 117, thus withdrawing bolt 133, operating linkage 109, 105, 111 and 119 to withdraw bolt 135, and operating linkage 109, 105, 103, 91, Fig. 8, 89, 83 and sear 41 to withdraw bolt 29.