Oct. 8, 1946. R. P. MURDOCH AIRCRAFT Lunma GEAR Filed April 12. 1943 2,408,870 @?ented Get. 8. i946 2,408,870} tree , s'mrss PATENT OFFICE 2,408,870 AIRCRAFT LANDING GEAR Robert P. Murdoch, Mount Lebanon, Pa. I Application April 12, 1943, Serial No. 482,686 I 1 Claim. (cl. 244-103) 1 2 This invention relates to new and useful im provements aircraft landing gear, and it is The invention does not involve the operating mechanism for‘the wheel carriage, which is there- , fore not shown. Mounted on the carriage frame 4 is a friction drive wheel 8 rotatable by a shaft among the objects thereof to provide means for rotating the wheels of aircraft preparatory ‘to landing to avoid the abrasive action of the ground 5 9 of an electric motor ill, the shaft 9 being biased ' surface on the wheels resulting if the wheels are by springs 9“ so that the friction wheel 8 is at static. , all times in contact with the outer periphery of the landing wheel 2 to ‘be capable of rotating the It has heretofore been proposed to utilize vanes on the wheels of airplanes, which will rotate the ‘latter when it is free and off the ground. wheels in response to the air flow when the land 10 ‘The arm 6 of the toggle is split and'provided lng gear is dropped prior to landing. An obvious with a shock absorber H which may he of the disadvantage of this type of actuator is the added spring or pneumatic type, or both, in which a pis resistance or load in the take-oil‘ as the wheels ton member It operates in a cylinder is. The cannot be immediately retracted ‘until the ship cylinder is provided with an electrical contact has reached a sale altitude. 15 it which constitutes a terminal in the circuit of motor l0, and the piston i2 is provided with the In accordance with the present invention, means are provided to positively drive the wheels by a prime mover contained within the wheel housing or mounted on the wheel carriage, there spring biased contact i5 which also constitutes a terminal of the circuit of motor ill. Contacts M and it are shown separated in the by ordering no resistance to the normal ?ight of go position of the shock absorber in Fig. 3, which is the plane. . ‘ the position of same in the retracted position of I The invention further contemplates a motor the landing gear. . In Fig. 4 when the links 5 and t of the toggle drive which shall maintain positive contact with are vertical, the piston 32 is displaced to the po= the wheel at all times so that the wheels may be positively rotated when the‘ landing gear is in g5 sition where terminals ill and 95 contact to en its fully extended position. ergize the drive motor it‘), and in Fig. 5 the ter— A further object of the invention is the provi~ minals It and B5 are separated'by the weight of the plane on the landing gear after the plane is slon of a motor drive which shall be capable of revolving the landing wheels at approrlmately landed. In this position, the motor circuit is the landing speed of the plane, and still a further 39 broken and the drive motor itstops. object of the invention is'tlie provision of means To control rotation of the landing wheels 2' to proximate the speed of the wheels at the normal for automatically energizing the motor circuit landing speed of the plane, the drive motor ii) when the carriage has been extended to landing position, and to automatically disconnect the mo» is wound as a constant speed torque motor, devel=~ from the power circuit when the plane is g5 oping a. maximum speed corresponding to the pen ripheral speed of the wheels at the landing speed landed. These and other objects oi’ the invention will . of the plane. When the carriage is lowered, which become ‘more apparent from a consideration oi’ establishes the power circuit for the drive motor the accompanying drawing constituting a part it], it will rotate at slow speed while developing her-sci’ in which like reference characters desig= to the torque needed to rotate wheel 2 and gradually bring it up to the landing speed which is the note like parts, and in which: maximum speed of the motor it. Fig. l is a iront elevaticnal view of an airplane Although one embodiment of the invention has motor housing partially cut away, showing the‘ landing gear embodying the principles of this been herein illustrated and described, it will be 45 evident to those skilled in the art that various invention: modi?cations may be made in the details of con Fig. 2 a top plan view of the wheel drive and a portion of the wheel carriage; and‘ ‘ Figs. 3, 4 and 5 vertical cross~secticnalviews of _ a shock absorber on the wheel carriage having electrical contacts therein. ' 59 With reference to. the‘ several ?gures of the drawing, the numeral ‘i designates the engine struction without departing from the principles herein set forth. I claim: I In combination with a landing gear and land ing wheels for aircraft, a positive drive for said wheel comprising a friction wheel in contact with nacelle, having the landing gear mounted on one the outer periphery of the landing wheel, an elec‘'-. tric motor for driving said friction wheel, and’ dated rubber tires or wheels 2 journalled on axle 55 means responsive to movement of the landing mounted on the carriage generally designated gear to its extended position for energizing said by the numeral 6, The carriage is provided with motor and for deenergizing the motor circuit by links ‘5 and S pivoted at ‘l and to the wheel axle I the impact of the landing wheel with the ground. 3,, and are shown in the retracted position, the side thereof, the landing gear comprising the in links being a toggle which forms a straight verti cal strut when the wheel carriage is dropped. 60 l ROBERT P. M'URDOCH.