Abstract:
A jack for servicing the landing wheels of aircraft in which a scissor jack is provided with an adaptor to fit the underside of aircraft and is so oriented that it extends equally to either side of the jack. A selected end of the adaptor is used to engage the aircraft landing gear making it possible to place either side of the jack closely adjacent a landing wheel at either side of an aircraft.

Description:
REFERENCE TO RELATED APPLICATION(S)  
       [0001]     This application claims priority of U.S. provisional patent application Ser. No. 60/516,337 filed Oct. 31, 2003, the entire content of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to jacks and more particularly to jacks of the scissor type adapted for use with light airplanes.  
       BACKGROUND OF THE INVENTION  
       [0003]     Small airplanes often are delayed at airports when it is necessary to repair wheels and tires of the landing gear. Maintenance requires a jack and the usual jacks available at airports are very large and cumbersome, often requiring a skilled operator. This causes delays in conducting maintenance. It would be desirable to have a simple mechanical jack that is compact for storage and transport and which is light in weight so that it can be carried on board a light airplane where weight is critical making it feasible for an aircraft operator to carry a jack and have it available when needed.  
       SUMMARY OF THE INVENTION  
       [0004]     It is an object of the invention to provide a jack which is small and compact and light in weight so that it can be transported with the maintenance tools in a light airplane fitted with either fixed or retractable landing gear.  
         [0005]     It is another object of the invention to provide an airplane jack which can be used for maintenance on the undercarriage of light airplanes and can be placed closely adjacent to the landing wheels for desirable operation.  
         [0006]     The objects of the invention are attained by a screw actuated scissor jack having an adapter at its upper, movable end which forms a trough having a generally semi-circular cross section and is disposed with its axes transverse to the axis extending equally to opposite sides of the jack. The adapter conforms to the underside of many light aircraft landing gear so that selected extending portions of the adapter may be used to locate the jack closely to the aircraft wheel for servicing purposes. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a perspective view of the airplane jack embodying the invention in position relative to one of the landing gear of an aircraft;  
         [0008]      FIG. 2  is a side elevation of the airplane jack in a raised position; and  
         [0009]      FIG. 3  is a plan view from one end of the airplane jack in  FIG. 2 .  
     
    
     DETAILED DESCRIPTION  
       [0010]     The airplane jack of the present invention is designated in its entirety at  10  and includes a scissor-jack portion  12  and an adapter  14 . The jack portion  12  includes a base member  16  which is intended to be placed on a firm, flat and stationary surface such as a hanger floor or apron. The base member  16  pivotally supports a pair of oppositely extending links or arms  18  and  20 , from a pair of spaced pivot pins  22  extending transversely of elongated base  16 . The arms  18  and  20  have channel shaped cross sections which open upwardly. The adjacent ends of arms  18  and  20  are provided with teeth  24  on each of the flanges of the channel shaped arms that are concentric with pins  22  and in mesh with each other to maintain the angles of the two arms relative to the horizontal base  16  equal to each other.  
         [0011]     The outer end of arm  18  receives a downwardly opening channel formed by the cross section of an upwardly and inwardly extending arm  26 . The arms  18  and  26  are pivoted together at the axles of a trunnion member  28 . The outer ends of the oppositely-extending lower arm  20  receives an outer end of an upwardly and inwardly extending arm  30  and the two arms  20  and  30  are pivoted relative to each other by the axles of a second trunnion member  32 .  
         [0012]     The upper inner ends of arms  26  and  30  are received within a channel shaped support member  36  and are pivotally connected to the channel by a pair of spaced pins  38 . The upper inner ends of arms  26  and  30  are provided with teeth  42  on each of the channel flanges and like the teeth  24  associated with the lower arms  18  and  20 , act to maintain the angular relation of the upper arms relative to the horizontal channel shaped support member  36 .  
         [0013]     The upper inner ends of the arms  26  and  30  with the pivot pins  38  and channel member  36  can be positioned at various elevations relative to the base  16  by a means of a threaded shaft  46  having one end rotatable but axially fixed in the trunnion  32 .  
         [0014]     The shaft  46  is threaded over a major portion its length as indicated at  50 . The threads  50  are received in an internally threaded portion of the trunnion  26 . Rotational movement of the shaft  46  in opposite directions causes scissoring action of the links or arms  18 ,  20 ,  26  and  30 , which have substantially equal lengths forming the four sides of a rectilinear linkage system. During such rotation of shaft  46 , the trunnions  28  and  32  located at diametrically opposed corners of the linkage system move toward and away from each other. Also, the linkage system formed by arms  18 ,  20 ,  26 ,  32  moves in the same general vertical plane in use.  
         [0015]     In the collapsed position of jack  12 , the arms  18  and  20  lie horizontally with their channel shaped cross sections opening upwardly to receive the shaft  46 . Also, the arms  26  and  30  seat within the channel shaped member  1 . 8  and  20  and cover the shaft  46 . The resultant package is elongated and compact.  
         [0016]     A more detailed description of such scissor-jacks can be found in U.S. Pat. Nos. 5,364,071 and 6,375,161.  
         [0017]     The top surface of channel member  36  is provided with the adapter  14  which is semi-circular in cross section with its axis generally parallel to the pivot axes of the members and elements at  22 ,  28 ,  32  and  38 . Adapter  12  is fixed as by welding to channel member  36  and forms an upwardly opening trough engagable with the underside of the curved portion of an aircraft landing gear  52 .  
         [0018]     The adaptor  14  also is elongated so that it has portions  56  and  58  extending equal distances in opposite directions beyond the outer extent of the upper arms  26  and  32  as best seen in  FIG. 3 . The extensions  56  and  58  of the adapter  14  make it possible to position the relatively flat jack  12  close to the landing wheel  60  of an airplane, as seen in  FIG. 1 .  
         [0019]     In use, the jack  12  is positioned as indicated in  FIG. 1  with one extended end  56  or  58  of the adapter  40  in engagement with a lower curvilinear surface of a casting of the aircraft landing gear indicated at  52  forming part of the structure supporting one of the aircraft landing wheels  60 . Such curved surfaces are common to many aircraft. By way of example, the curved surface of adapter  14  which has an internal diameter of about one and five eighths of an inch (4.1 cm) is found to be complementary to the curved surfaces of landing gear on aircraft manufactured by Piper and Beechcraft. The extensions  56  and  58  of adapter  14  permit the jack  12  to be placed closely to the inner surface of the wheel  60  so that subsequent actuation of the jack by means of a handle having a socket to receive the hexagon head  62  at the end of threaded shaft  46 . Rotation of the head  62  elevates the adapter  14  and raises the wheel  60  of the aircraft for servicing. With the head  62  facing the same end of the aircraft, the jack  12  can be placed at the opposite landing gear wheel, using the opposite extended end  46  or  48  of the adapter  14  to engage the casting on the aircraft landing gear  52 .  
         [0020]     If it should become desirable to have the head  62  of shaft  46  extending toward the opposite end of the aircraft, the extension  58  is used instead of extension  56 . Similarly, at the opposite side of the aircraft, the extension  56  would be used instead of extension end  58 .  
         [0021]     An aircraft jack has been provided which is relatively light and compact and can be carried with the aircraft. An actual unit was found to weigh only four and one-half pounds. The jack has an aircraft-engaging adapter which is semi-circular in cross section to mate with the typical curved structure forming the landing gear of the aircraft and extends transversely of the body of the jack so that the jack can be placed closely to the point where the aircraft must be engaged to be lifted.