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Oct. 8, 1946.
Filed April 12. 1943
@?ented Get. 8. i946
tree , s'mrss PATENT OFFICE
Robert P. Murdoch, Mount Lebanon, Pa.
I Application April 12, 1943, Serial No. 482,686 I
1 Claim.
(cl. 244-103)
This invention relates to new and useful im
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
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
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
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
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.
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:
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.
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