GB2237781A

GB2237781A - Aircraft landing gear

Info

Publication number: GB2237781A
Application number: GB8920252A
Authority: GB
Inventors: David Anthony Smart
Original assignee: Dowty Rotol Ltd
Current assignee: Dowty Rotol Ltd
Priority date: 1989-09-07
Filing date: 1989-09-07
Publication date: 1991-05-15
Anticipated expiration: 2009-09-07
Also published as: GB2237781B; GB8920252D0

Abstract

A landing gear comprises a main leg having a lower component (1) and an upper component (2), and a shortening mechanism which comprises a piston rod (18) which extends through orifices (4, 10) in the lower log component (1) and the upper leg component (2) and acts internally within the main leg during retraction thereof to shorten the overall length of the main leg. The piston rod (18) preferably engages with a surface (3) of the lower leg component (1) to enable the lower leg component to be partially retracted into the upper leg (2) component, and a linkage arrangement comprising a link (21) attached to a fixed member provided on an aircraft in which the landing gear is mounted, and pivoted at (19) to one link (22) attached to the piston rod (18) and to another link (20) attached to the main leg member. <IMAGE>

Description

A LANDING GEAR ARRANGEMENT This invention relates to a landing gear arrangement for use on an aeroplane, and in particular to a landing gear arrangement provided with a new means for shortening the length thereof on retraction of the landing gear arrangement.

The present invention is concerned with providing a landing gear arrangement having an internally acting shortening mechanism.

In accordance with the present invention a landing gear arrangement comprises a main leg member having a lower leg component and an upper leg component, and a shortening mechanism, wherein the the shortening mechanism comprises a piston rod member whIch extends through orifices provided in the lower leg compenerlt and the upper leg component and is disposed so that it acts internally within the main leg member of the landing gear arrangement during retraction thereof to shorten the overall length of the main leg member.

Normally with a landing gear made in accordance with the present invention the main leg member is provided with a means which is, either directly or indirectly, pivotally connected to the aircraft.

In a preferred arrangement of the present invention the piston rod member engages with a surface of the lower leg component to enable the lower leg component to be inwardly retracted with respect to the upper leg component, and a linkage arrangement in which the linkage has one link member attached to a fixed member provided on an aircraft into which the landing gear arrangement is mounted, and one link member attached to the piston rod member.

Preferably, with the above mentioned arrangement of the present invention the guide linkage comprises three link members having a common pivotal mounting to one another at one end thereof with the other ends pivotally mounted as follows: - a first link member to a fixed point on the aircraft; - a second link member to the piston rod member of the shortening member; and - a third link member to the main leg member.

In the arrangement of the present inventIon envisaged the third link member is attached to the main leg member, which is pivotally attached the aircraft, at position in close proximity to the pivotally attachment of the main leg merger te the aircraft.

Preferably, the main leg member is 2 hydaulically operated mechanic in which the end of the piston rod member disposed within the lower lec component is of the same, or substantially the same, diameter as the internal diameter of the lower leg component. In circumstances where the main leg member is provided with a partial atmosphere of an inert gas, for example nitrogen, when the pressure has not been increased above the fully extended pressure, the pressure acts against the piston rod member and lower leg member in equal or substantially equal amounts. Therefore, no tendency occurs, or exists, leading to a force attempting te force the piston rod member and the lower leg member apart.

However, it is not essential to the operation of the present invention that the above mentioned diameters are the same. The landing gear arrangement can be adapted to cater for any forces that may result frc differing diameters in the landing gear arrangement. Obviously, it is advantageous to keep the differences between the diameters, an therefore forces induce , a mlnimur.

The invention also includes an aircraft inzlucina a landing gear arrangement made in accordance with the present invention.

The invention wlll now be illustrated by way of description of an example with reference to the accompanying drawing, in which: Figure 1 shows a section view of a landing gear arrangement in an extended position, made in accordance with the present invention; and Figure 2 shows a section view of the landing gear shown in Figure 1 in the retracted position.

Referring to Fia-~res 1 and 2 of the drawings, a landing gear arrangement made in accordance with the present invention includes a main leg member having a lower component 1 and an upper component 2, and a shortening mechanism.

In operation the lower component 1 of the main leg member is arranged so that it telescopes within the upper component of the main leg member.

The lower component 1 of the main leg member is provided with: - a widened head section 3 having a centrally positioned orifice 4; - a mounting block member 5; and - two internal chambers 6, 7, the upper 6 of which has the orifice 4 opening there into.

The upper component 2 of the main leg member is of generally tubular configuration ha~ing an opening 8 at one end a closed wall section 9 with a centrally dispose orifice 10 at the other end, and is provided with: - an inwardly extendng collar section li which in operation retains the lower component 1 wIthin the upper component; - a sealing member 12 around the opening s which sealingly engages with the lower component 1; - a sealing member 13 which surrounds the orifice 10 in the closed wall section 9; - a mounting hook 14 at the lower end of the upper component; and - mounting means 15 which enables the upper component 2 of the main leg member to be pivotally attached to the aircraft.

A linkage arrangement having an upper link 16 which is pivotally attached to a lower link 17 so that it acts between the mounting hook 14 of the upper component 2 and the mounting block member 5 of the lower component 1.

The shortening mechanism comprises a linkage arrangement and a piston rod member 18.

The linkage arrangement of the shortening mechanism includes three links 20, 21, 22 which are all connected at a common pivotal mounting 19.

The first linkage member 20 is pivotally attached to the mounting means 15 of the upper component 2 at a point close to the pivotal mounting of the main leg member to the aircraft.

The second linkage member 21 is pivotally attached to a mounting point 23 provided on the aircraft.

The third linkage member 22 is pivotally attached to one end of the piston rod member 18.

The piston rod member 18 is disposed so that it extends through the orifices 10 in the closed wall section 9 of the upper component 2 and the oriface 4 in widened head section 3 in the lower component 1. The upper end of the piston rod member 18 being the end pivotally attached to the third linkage member 22, whilst the lower end of the piston rod member 18 is widened so that it engages with the area of the lower component surrounding the oriface 4 therein.

When assembled, the lower component 1 of the main leg member is disposed within the upper component so that the widened head section 3 is between the closed wall section 9 and collar section 11, and the sealing member 12 sealingly engages the lower component 1 dividing the space within the upper component 2 into two distinct spaces 23, 24. The lower space 23 is wholly filled with hydraulic oil, whilst the upper space 24 contains a volume of hydraulic oil having an inert gas such as nitrogen disposed thereabove.

In operation when the landing gear is retracted into the aircraft the main leg member is caused to move in the direction of arrow A. In turn this causes the first and third linkage members 20, 22 which have a common, or substantially common, axis in the landing gear extended position to be pulled out of this relationshiF, so causing the piston rod member 18 to be moved upwards relative to the upper component 2 of the main leg member.

The relative upward movement of the piston rod member 18 causes its widened end to engage the lower component. Therefore, under further retraction of the landing gear, the lower component 1 is drawn within the upper component of the main leg member, so shortening the effective length of the main leg member.

The reverse happens upon extension of the landing gear arrangement.

Claims

1. A landing gear arrangement comprising a main leg member having a lower leg component and an upper leg component, and a shortening mechanism, wherein the the shortening mechanism comprises a piston rod member which extends through orifices provided in the lower leg component and the upper leg component and is disposed so that it acts internally within the main leg member c the landing gear arrangement during retraction thereof to shorten the overall length of the mzl leg member.

Amendments to the claims have been filed as follows CLAIMS 1. A landing gear arrangement comprising a main leg member having a lower leg component and an upper leg component, and a shortening mechanism, wherein the the shortening mechanism comprises a piston rod member which extends through orifices provided in the lower leg component and the upper leg component and is disposed so that it acts internally within the main leg member of the landing gear arrangement during retraction thereof to shorten the overall length of the main leg member.

2. A landing gear arrangement as claimed in claim 1 in which the main leg member is adopted to be pivotally connected to an aircraft so as to pivot when retracted into the aircraft.

3. A landing gear arrangement as claimed in claim 2 in which the piston rod member engages with a surface of the lower leg component to enable the lower leg component to be inwardly retracted with respect to the upper leg component.

4. A landing gear arrangement as claimed in claim 3 in which a linkage arrangement connected to the piston rod member is adopted to be connected to a fixed member on the aircraft so as to move the piston rod member to retract the lower leg component when the main leg member is retracted into the aircraft.

5. A landing gear arrangement as claimed in claim 4 in which the linkage arrangement comprises linkage means connected between the piston rod member and the main leg member, and a link member connected between said linkage means and said fixed member on the aircraft.

6. A landing gear arrangement as claimed in claim 5 in which the linkage means comprises a pair of links connected by a central pivot which is connected to said link member.

7. A landing gear arrangement as claimed in claim 6 in which said pair of links are substantially longitudinally aligned when the main leg member is fully extended.

8. A landing gear arrangement as claimed in any preceding claim in which the lower and upper leg components are sealingly engaged with one another and adapted to have a damping action when they move axially relative to one another.

9. A landing gear arrangement substantially as herein described by way of example with reference to the accompanying drawings.