BACKGROUND OF THE INVENTION

This invention concerns an aircraft wheel brake cooling apparatus.

When large aircraft make high energy stops that is they use perhaps reverse thrust and maximum application of the wheel brakes the latter heat up considerably and due to the mass of the brake assembly and associated wheel and the good conductivity to the aircraft tyre there follows when the aircraft is at rest a dangerous increase in tyre pressure which must be relieved. Deflation of the tyres is hazardous because of the possibility that the two bolted halves of the wheel may burst apart while deflation is being attempted.The brakes may not cool to ambient for two -hours. If the aircraft is scheduled to take off shortly after landing which is common on short routes the brakes will be subject to a further application before cooling adequately from the high energy stop. OBJECTIVE AND SUMMARY OF THE INVENTION This invention seeks to provide an apparatus which reduces the risk of damage to the wheel and tyre by overheating during the period following a high energy stop.

This invention provides a wheel brake cooling apparatus for aircraft comprising a clamp asserαbly for attachment to an aircraft tyre, a duct adapted to be clamped by the clamp asseribly against an aircraft wheel upon which the tyre is fitted,

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and a fan arranged, when activated, to draw cooling air through the wheel brake assembly via the duct.

A clamp assembly may comprise a tyre-straddling, U-shaped frame with a first tyre engaging pad for one sidewall of the wheel and a second tyre engaging pad for the opposite side wall and means to clamp the pads against the tyre. The frame may be made of a major part, the length of which exceeds the greatest sidewall to sidewall width of the tyre, which part carries an inwardly directed pad for engaging one sidewall, a minor part which is pivoted to the major part, which minor part carries a complementary pad for engaging the opposite sidewall and a lever operated linkage for clamping the pads on the parts of the frame to the tyre. The duct may be of circular cros sectiβn and. may have a ring seal at the front edge thereof in order to mate with the wheel hub. Preferably th fan is an axial flow fan supported in a cylindrical housing of a smaller cross-sectional area than the duct and the duc may extend from the housing on the input side of the fan. The duct may be releasably attached to the clamp assembly b a hook assembly which affords pivotal connection between the frame and the duct, the hook assembly being of adjustab length so as to permit the duct to mate closely with the wheel. BRIEF DESCRIPTION OF DRAWINGS

One embodiment of the invention is now described by way of example with reference to the accompanying drawings wherein

Fig. 1 is a diagrammatic section of the apparatus and the aircraft wheel to which it is applied Fig. 2 is a side view of the clamp assembly Fig. 3 is a plan of the clamp assembly. DESCRIPTION OF PREFERRED EMBODIMENT

Referring to Fig. 1, the aircraft wheel has two hub sections 2, 4 clamped together by bolts 6. A multiple disc brake assembly 8 is located within hub section 4. Hub section 12 is pierced by cut-outs 10. The wheel supports a tyre 12. A frame 14 straddles the tyre 12 and crossbar 16 thereon supports a hook assembly 18 which is welded to the struts 20 of the duct 22. The duct is a sheet aluminium frustrum which coaxially overlaps an aluminium motor housing 24 the open end of which is protected by a grid 26. The inlet end of the frustrum has a rolled edge 28 which is protected by a rubber seal 30 An axial flow fan 32 is mounted within the housing 24 on arms 34 (only one shown) and is supplied with 115v DC from a ground supply or from the aircraft generators. The fan produces a flow of 1400 cfm. The duct is stiffened by six tubular struts 36. The hook assembly 18 welded to the upper pair of struts consists of two slotted plates 38 which locate a pin 40 and a pair of tubes 42 each provided with adjustable screws 44 and hooks 46 for engaging cross bar 16.

Referring now to Figs. 2 and 3 the clamping frame 14 consists of a major tubular part 48 provided with a pair of

pads 50 which abut a sidewall of the tyre 12. A minor part 52 of the frame carries complementary pads 54. The major and minor parts of the frame are pivotally connected by pins 56, 58 and normally urged into a clamping position by spring 60 but are openable by use of the lever and linka 62. After a high energy stop the discs may reach 850 F. The clamp assembly is fitted to the tyre and the duct seale to the wheel. Air is drawn through the cut outs creating a air stream over the discs which cool rapidly in the first five minutes. Twenty minutes is generally required to redu the wheel mass to ambient.

We have found the advantages of the apparatus to be

1. Ease of use due to lightness of construction

2. Adaptability to different sizes of tyres 3. The apparatus can be applied from positions fore and aft of the wheel- so ^" that personnel need not stand in line with the direction of separation of the hubs.

4. The rapid cooling reduces the risk of distortion in the brakes.'