GB2161202A - Locking means for retractable devices - Google Patents

Abstract

A locking means 8, co-operable with a pin 7 fast with an aircraft undercarriage, comprises a retention member 16 which includes a first portion 17 pivotally-connected to fixed structure 9 and a second portion 19 with which the pin is engageable. Portion 19 is of hook shape and pivotally- connected to portion 17. The latch 32/33 is co-operable with portion 17. Holding means 21 is provided which in its operative condition locks portions 17 and 19 together and which in its inoperative condition permits pivotal movement of portion 19 with respect to portion 17. First operator means 28 so controls the latch as to permit pivotal movement of portion 17, 19 together as one about the pivotal connection of portion 17 to fixed structure thus to permit release of the pin and undercarriage extension. Second operator means 38 is capable of so effecting movement of the holding means as to permit pivotal movement of portion 19 with respect to portion 17 for release of the pin. <IMAGE>

Description

SPECIFICATION Locking means for retractable devices This invention relates to locking means for retractable devices, for example up-lock means for aircraft undercarriages or for aircraft ram air turbine units which when not in use are required to be securely held in a retracted condition in a suitably shaped stowage zone in the associated aircraft.

Hitherto certain such up-lock means have included a hook or like member pivotally-mounted upon an aircraft and co-operable with a pin or the like fast with a portion of the retractable device. On retraction of the device the hook or like member has automatically locked on to the pin and, for subsequent release of the pin to permit re-extension of the device, the hook or like member has been moved about its pivotal mounting by suitable fluidpressure-operable or electrically-operable actuator means through the intermediary of a latch. In some constructions provision has been made for emergency release of the up-lock means in the event that the fluid-pressure-operable or electrically-operable actuator means fails to operate.Here a mechanical connection has been made to the hook or like member so that it can be moved about its pivotal connection without hindrance from the failed actuator means. However, in practice such emergency release has on occasions not been possible due to jamming of the latch itself, for example by foreign objects inadvertently engaging it or ice accumulations engaging it, with serious, if not disastrous, consequences.

The invention as claimed is intended to provide a remedy. It solves the problem of how to design a locking means so constructed that in the event of failure of its actuator means, or jamming of the latch, emergency release is nevertheless obtainable.

According to this invention locking means, suitable for a retractable device carried by an aircraft or the like, and co-operable with a pin or the like fast with said retractable device, comprises a retention member which includes a first portion pivotallyconnected to fixed structure and a second portion with which said pin on retraction of said device is operably engageable, said second portion being of hook or like shape and pivotally-connected to said first portion, a latch co-operable with said first portion, holding means which in its operative condition locks said first portion and said second portion together and which in its inoperative position permits pivotal movement of said second portion with respect to said first portion, first operator means for so controlling said latch as to permit pivotal movement of said first portion and said second portion together as one about the pivotal connection of said first portion to said fixed structure and thus to permit release of said pin and extension of said retractable device, and second operator means capable, in the event that said first portion fails to move about said pivotal connection, of effecting movement of said holding means to its inoperative position thereby to permit pivotal movement of said second portion with respect to said first portion and consequent release of said pin.

Preferably said first operator means comprises a fluid-pressure-operable actuator and said second operator means comprises a manually-controlled linkage or the like.

The retention member may be carried by a frame structure or the like, itself fast with said fixed structure and said latch may be pivotally-mounted on said frame structure. The latch may include a roller which is engageable with a suitably shaped recess formed in said first portion of said retention member.

The holding means may comprise a spring-loaded link member pivotally-connected at one end to said first portion of said retention member and carrying at its other end portion a roller which is engageable with a suitably-shaped recess formed in said second portion of said retention member.

The advantages offered by the invention are mainly that if the first operator means fails to operate for release of the locking means or if the latch jams so that the first portion of the retention member becomes immovable, the second operator means can be used to release said locking means.

One way of carrying out the invention is described in detail below with reference to drawings which illustrate only one specific embodiment, in which Figure 1 is a front elevation of an aircraft main undercarriage and associated up-lock means for holding the undercarriage in its retracted condition, Figure 2 is an enlarged side elevation of the uplock means shown in Figure 1, Figure 3 is a view taken along the line Ill-Ill in Figure 2, Figure 4 is a view taken in the direction of the arrow IV on Figure 2, and Figure 5 is a view also taken in the direction of the arrow IV on Figure 2, but with the up-lock means in a different operating condition from that of Figure 4.

The retractable undercarriage shown in Figure 1 comprises a leg 1 which carries wheels 2 and which is pivotally-mounted at 3 to fixed aircraft structure as at 4. The undercarriage is retractable about pivotal mounting 3 into stowage zone 5 by a suitable fluid-pressure-operable retraction jack 6. As on retraction the undercarriage reaches its stowed condition in zone 5, a pin 7 fast with leg 1 engages an up-lock means 8 disposed in zone 5 and fast with fixed aircraft structure.

As shown in Figures 2 to 5 up-lock means 8 includes a frame structure 9 formed by two parallel plate members 10,11 which are bolted two a mounting bracket assembly 12. This assembly provides two fixing points 13, 14 by which the uplock means is securely fastened to the aircraft structure. The lower end portion of each plate member is provided with a recess 15 of generally inverted V-shape and radiussed at its base, the two recesses providing a pair of seatings for pin 7.

A retention member 16 is carried by, and disposed between, the two plate members of frame structure 9. The retention member comprises a first portion 17, which is mounted for pivotal rocking movement about the axis 18 and with respect to structure 9, and a second portion 19 which is mounted for pivotal rocking movement with respect to first portion 17 and about the same axis 18. Second portion 19 has a hook formation 20 co-operable with recesses 15 and with pin 7.

Holding means includes a link member 21 which is pivotally-connected at 22 at one end thereof to a projection 23 of first portion 17 and which is slotted at 24 at its other end to receive a roller 25 carried thereby. This roller is co-operable with a recess 26 of semi-circular shape formed in second portion 19 of retention member 16. A tension coil spring 27 which is connected between portions 17 and 19 assists in normally holding the roller 25 in engagement with recess 26 as shown in Figure 3 and thus those portions are then locked together as a single member.

First operator means in the form of a fluidpressure-operable jack 28 is secured to plate member 10, the piston rod 29 of this jack engaging a lever 30 fast with shaft 31 mounted in suitable bearings in plate members 10, 11. A further lever 32, also secured to shaft 31, carries a roller 33 which, as shown in Figure 3, normally engages a semi-circular recess 34 formed in first portion 17 of retention member 16. Thus lever 32 and roller 33 together form a pivotal latch. A pair of tension coil springs 35, 36 respectively disposed on the outer side of plate members 10, 11 are connected between member 21 and lever 32.

The member 21 is provided with a transverse portion 37 to the free end of which second operator means in the form of a mechanical linkage, partly shown at 38, is suitably attached. The point 39 of connection of this linkage with the portion 19 is coincident with the axis 18 about which the first and second portions 17, 19 of retention member 16 are rockable.

When it is required to retract the undercarriage from its extended condition shown in Figure 1 to its retracted position in stowage zone 5, the jack 6 is extended and leg 1,togetherwith its wheels 2, is caused to hinge upwardly about its pivotal mounting 3 until pin 7 reaches up-lock means 8.

Normally the up-lock means is in the condition shown in Figure 4 in readiness to receive pin 7. In this condition the latch roller 33 is disengaged from recess 34 while the roller 25 of the holding means is engaged with recess 26.

Upon pin 7 moving into recesses 15 it strikes the edge 40 of portion 19. Thus under the momentum of the retracting undercarriage the two portions 17 and 19, now held together as one by holding means 211 25, are moved in the anticlockwise direction as viewed in Figure 4 about axis 18. This movement continues until the hook formation 20 is disposed beneath pin 7. Simultaneously, and since under these conditions the jack 28 is not pressurised, the lever 32 is caused by spring means 35, 36 to pivot in the anticlockwise direction as viewed in Figure 4 so that the latch roller 33 engages recess 34. Thus the up-lock assembly is now in the condition shown in Figure 3 and the undercarriage is locked in its retracted condition.

When, subsequently, it is desired to extend the undercarriage, jack 28 is extended by the application of fluid under pressure thereto and its piston rod 29 causes the lever 30, shaft 31 and latch 32/33 to move together in the clockwise direction whereupon roller 33 is released from engagement with recess 34. This permits portions 17 and 19, now locked together by holding means 21/25, to move together as one in the clockwise direction about axis 18 under the effort of springs 35, 36 and under the weight of the undercarriage. As this occurs roller 33 rides over the nose formation 41 of portion 17 and hook formation 20 is moved away from its position beneath pin 7 to its position shown in Figure 4. Thus the pin is released from its engagement with the up-lock means and the undercarriage is permitted to extend in readiness for landing of the associated aircraft.

The fluid pressure supply to jack 28 is cut off but the up-lock means remains in the condition shown in Figure 4 in readiness to receive pin 7 on the next occasion of undercarriage retraction.

If upon retraction of the undercarriage the jack 28 fails to operate or becomes jammed, or if the latch becomes jammed by foreign matter or ice accumulation, so that portion 17 is immovable and hence portions 17, 18 cannot be moved in their locked-together condition for release of pin 7, the second operator means is brought into use. Thus the mechanical linkage, partly shown at 38, is operated and as shown in Figure 5 the holding means formed by member 21 and roller 25 is swung outwardly of portion 19 about pivot 22 so that roller 25 becomes disengaged from recess 26. Hence portion 19 is free to move in the clockwise direction about axis 18 and with respect to the now immovable portion 17, this movement being under the effort of spring 27 and under the weight of the undercarriage.When portion 19 reaches the position shown in Figure 5, pin 7 is released and the undercarriage is permitted to extend despite the above-mentioned jamming of the jack and/or latch.

Thereafter the undercarriage can be retracted, if really necessary, with the above jamming persisting. On such retraction, pin 7 again strikes edge 40 of portion 19 and that portion is caused to pivot in the anticlockwise direction about axis 18 under the momentum ofthe retracting undercarriage. Such pivoting movement is with respect to the still immovable portion 17 of retention member 16 and continues until hook formation 20 is disposed beneath pin 7, whereupon link member 21 is permitted under the spring means acting upon it to so swing about its pivot 22 that roller 25 reengages recess 26. Thus in the manner shown in Figure 3 portions 17 and 19 are again locked together and pin 7 is securely held by the up-lock means 8 to maintain the undercarriage in its retracted condition.

Although in the embodiment above described with reference to the drawings the first operator means is in the form of a fluid-pressure-operable jack and the second operator means comprises a mechanical linkage, in other embodiments of the invention other suitable forms of operator means may instead be used, for example electricallyoperable means.

Further, although in the embodiment above described with reference to the drawings the arrangement is such that two parallel tension springs are provided in association with retention member 16 and a single tension spring is provided in association with holding means 21/25, in alternative embodiments of the invention other suitable spring arrangements may instead be used, those arrangements in some cases employing springs of a form other than tension springs and/or differing numbers of springs.

Again, although in the embodiment above described with reference to the drawings the locking means is applied to an aircraft undercarriage, in other embodiments the invention is with advantage applied to other devices required to be moved from an extended position to a retracted position, and vice versa, for example ram air turbine units which when deployed into the slipstream of an aircraft or the like are used for generating emergency hydraulic and/or electrical power.

Other examples of devices to which the invention may also be applied are retraction doors for undercarriagesorforram airturbine units of aircraft or the like, and any other type of door or doors of an aircraft or the like which are required to be opened and closed during flight.

Claims (7)

1. Locking means suitable for a retractable device carried by an aircraft or the like, and co-operable with a pin or the like fast with said retractable device, comprising a retention member which includes a first portion pivotally-connected to fixed structure and a second portion with which said pin on retraction of said device is operably engageable, said second portion being of hook or like shape and pivotally-connected to said first portion, a latch co operable with said first portion, holding means which in its operative condition locks said first portion and said second portion together and which in its inoperative condition permits pivotal movement of said second portion with respect to said first portion, first operator means for so controlling said latch as to permit pivotal movement of said first portion and said second portion together as one about the pivotal connection of said first portion to said fixed structure and thus to permit release of said pin and extension of said retractable device, and second operator means capable, in the event that said first portion fails to move about said pivotal connection, of effecting movement of said holding means to its inoperative condition thereby to permit pivotal movement of said second portion with respect to said first portion and consequent release of said pin.

2. Locking means as claimed in claim 1, wherein said first operator means comprises a fluidpressure-operable actuator and said second operator means comprises a manually-controlled linkage or the like.

3. Locking means as claimed in either claim 1 or claim 2, wherein said retention member is carried by a frame structure or the like, itself fast with said fixed structure and said latch is pivotally-mounted on said frame structure.

4. Locking means as claimed in any one of the preceding claims, wherein said latch includes a roller which is engageable with a suitably-shaped recess formed in said first portion of said retention member.

5. Locking means as claimed in any one of the preceding claims, wherein said holding means comprises a spring-loaded link member pivotallyconnected at one end to said first portion of said retention member and carrying at its other end portion a roller which is engageable with a suitablyshaped recess formed in said second portion of said retention member.

6. Locking means substantially as hereinbefore described with reference to the accompanying drawings.

7. An aircraft undercarriage including locking means substantially as hereinbefore described with reference to the accompanying drawings.