GB1320011A - Retractable undercarriage for aircraft - Google Patents

Abstract

1320011 Retractable aircraft undercarriage MESSIER 26 June 1970 [27 June 1969] 31171/70 Addition to 1303663 Heading B7G In a modification of the undercarriage of the parent Specification, the slide valve fluid distributer (12) having three positions, which controls the supply of pressure fluid to the jack 23 operating the hatchdoor 16, is replaced by a first distributer 312 which can take up a first position assumed when the undercarriage is fully lowered and a second position assumed at other times, and a second fluid distributer 412 which also has two positions, one assumed when the undercarriage is locked in the retracted position and one when it is not. As well as being suitable for a case when the size of the undercarriage would necessitate a lengthy mechanical connection between the arms (6) and (9) of the original device, the modification ensures that the door is only closed after the undercarriage has been locked in its place. The distributers 312 and 412 are illustrated in their positions when the undercarriage is locked up, unlocked and fully lowered (Figs. 2-4 respectively, not shown). As in the parent Specification, 1,303,663, when the undercarriage is being lowered or retracted the door 16 is held open by the appropriate chamber 233 of jack 23 being supplied from whichever conduit is under pressure by way of spring clapper valves. Alternative embodiments of the present modifications also ensure that the door remains open, despite any fluctuations or failures of the hydraulic system, during movement of the undercarriage. Thus (Fig. 5) chamber 233 is connected directly to pressure line 104 via non- return valve 27 when the positions of modified distributers 512 and 612 correspond to the undercarriage being in motion. Alternatively, Fig. 6, a mechanical lock may be provided, clip 234 on the jack connection rod 231 being held over projection 235 by spring-loaded piston 236 when chamber 232 is not being supplied with pressure fluid. In a further embodiment, Fig. 7 and Figs. 8 and 9 (not shown) chamber 233 is fed with pressure fluid at all times, so as to tend to maintain the door open; when it is desired that the door be closed pressure fluid is fed also to chamber 232, which is of greater cross-section, so that the pressure in chamber 233 is overridden. This modification may also have the mechanical lock already described with regard to Fig. 6.