A three-wheeled vehicle in which the frame of a two-wheeled vehicle is pivotally interconnected with an assembly comprising two laterally positioned, steerable front wheels. In addition to causing the front wheels to turn, the rotational movement of the steering shaft having an integrally constructed spiral track simultaneously causes the frame to tilt by utilizing one end of an arm pivotally connected to the front wheel axle and the other end pivotally connected to tracking means for following the rotatable spiral track.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates to three-wheeled vehicles and particularly to 
three-wheeled vehicles that tilt when making turns. 
(2) Description of the Prior Art 
As the cost of petroleum products continues to rapidly increase, the need 
for cheaper means of transportation becomes more imperative. The 
replacement of four-wheeled vehicles with two-wheeled or three-wheeled 
vehicles as a means of achieving increased economy of operation, although 
readily apparent, has not achieved deserved acceptance primarily because 
of the safety hazards associated with the operation of two-wheeled and 
three-wheeled vehicles. The stability of two-wheeled vehicles, because of 
their two point contact with the ground, is much less than that which can 
be achieved with three-wheeled vehicles. However, three-wheeled vehicles, 
in most instances, are merely modified two-wheeled vehicles whereby a side 
car is attached as an adjunct to the basic two-wheeled vehicle. This 
arrangement is not entirely satisfactory because of asymmetric load and 
handling characteristics. To improve the stability of three-wheeled 
vehicles prior art discloses that a two-wheeled forebody section which 
forms the front part of the vehicle is coupled at its rear to the front of 
a standard two-wheeled motorcycle from which the front fork and front 
wheels have been removed. In another disclosure two front wheels are not 
only coupled to a motorcycle frame by means of parallelogram-type wheel 
support assembly, but means are also provided whereby an operator may 
apply a stabilizing force to effect a desired banking, or upright, posture 
for the operator and the frame while maintaining all three wheels at the 
same angle with respect to the ground. The former arrangement has not been 
entirely satisfactory because the frame cannot be banked in unison with 
one or more of the wheels and the latter arrangement also has not been 
entirely satisfactory for it requires the intervention of the operator to 
apply such stabilizing force. 
SUMMARY OF THE INVENTION 
In accordance with the teachings of this invention, a three-wheeled vehicle 
would be made more stable by having the rear frame which supports the 
operator and the rear wheel tilt according to the direction and degree of 
turning of the two front wheels. As the front wheels are turned through an 
angle, causing both the rear frame and the rear wheel to be increasingly 
tilted or inclined, the center of gravity is shifted making the vehicle 
more stable in the turn. Moreover, because the timing and the amount of 
tilting is automatic, the operator is not required to make a conscious 
effort to utilize this function. 
In order to produce such tiltable vehicle, either a three-wheeled would be 
originally constructed or a commercially available two-wheeled vehicle, 
such as a bicycle or a motorcycle or the like, would be modified to 
provide a three-wheeled vehicle whereby the front wheel is replaced by an 
assembly having two laterally positioned, steerable front wheels and a 
steering shaft having an integrally constructed spiral track such as a 
worm-gear and tracking means such as a worm-gear-nut responsive to the 
rotational movements of the worm-gear. The front fork of the frame of the 
two-wheeled vehicle and the steering shaft are pivotally connected to the 
assembly by means of an L-shaped cross member. The worm-gear-nut is 
pivotally connected by an arm to the front axle of the assembly while the 
steering shaft is connected to a front wheel subassembly by means of an 
adjustable arm to the L-shaped cross member. Whenever the steering wheel 
is turned, the worm-gear-nut ascends or descends the spiral incline plane 
of the worm-gear causing an angular change of the arm to the front axle in 
turn causing the rear frame and wheel to tilt in the direction the 
steering wheel is turned. 
It is therefore an object of the invention to provide an assembly having 
two laterally positioned, steerable front wheels to which a frame of a 
two-wheeled vehicle may be easily and operatively attached. 
It is a further object of the invention to provide a three-wheeled vehicle 
wherein the frame laterally tilts with the turning of the front wheels. 
Still another object of the invention is to provide a three-wheeled vehicle 
of enhanced safety characteristics that is relatively simple to construct 
and inexpensive to maintain and operate. 
Yet another object of the invention is to provide a three-wheeled vehicle 
which is capable of carrying a passenger in addition to a driver as well 
as cargo. 
Other objects and advantages of the invention will become apparent to those 
skilled in the art from the following detailed description taken in 
connection with the accompanying drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring to FIGS. 1-4, at the upper end of steering shaft 10 is attached 
steering wheel 11 while downwardly onto and concentrically with steering 
shaft 10 is attached worm-gear 12 by means of set screw 13. The head of 
stem 14, which is turned 90.degree. from that of conventional stems, of 
the forward section of a two-wheeled vehicle frame 15 rotatably secures 
the upper section of steering shaft 10 to frame 15 while collar 16 
vertically positions steering shaft 10 to frame 15. One leg of L-shaped 
lower cross member 17, which is parallel to the head of stem 14, rigidly 
interconnects the tines of front fork 18 of frame 15. Additionally, 
L-shaped lower cross member 17, which has a passageway 19 through which 
steering shaft 10 passes, rotatably secures the lower end of steering 
shaft 10 to frame 15 by means of connector 20. Forward of passageway 19 is 
the other leg, guide bar 21, of L-shaped lower cross member 17. L-shaped 
lower cross member 17 is pivotally connected to front axle 22 with 
connector 23 so that simultaneously whenever L-shaped lower cross member 
17 is tilted from the normal so are guide bar 21, steering shaft 10, 
steering wheel 11, and front fork 18 as well as frame 15. 
Worm-gear-nut 24, whose inner diameter is slightly larger than the outer 
diameter of worm-gear 12 which it encircles, engages worm-gear 12 by means 
of groove follower pin 25 and in addition groove follower pin 25 pivotally 
connects one tine of tilt fork 26 at its upper forked end to worm-gear-nut 
24. Connector 27 pivotally connects the other tine of tilt fork 26 to 
worm-gear-nut 24. At its lower end tilt fork 26 is pivotally connected to 
one extremity of front axle 22 by means of connector 28. Pivotally 
connected to the upper end of guide bar 21 is adjustable guide rod 29 
which in turn is pivotally connected to front wheel subassembly 30 located 
at the other extremity of front axle 22. 
Front wheel subassembly 30 is a rectangular box-type construction 
consisting of two parallel front-to-back members connected by two parallel 
cross members. Pivotally connected to an inward front-to-back member is 
adjustable guide rod 29. Each front wheel 31 is supported by front wheel 
hub 32 of front wheel subassembly 30. Connected to inward front-to-back 
member of front wheel subassembly 30 is yoke 33 which in turn is pivotally 
connected to front axle 22 with connector 34. The connector 43 pivotally 
interconnects right and left front wheel subassembly 30 by means of tie 
rod 35. Rigidly connected to front axle 22 by connector 39 are the two 
arms of Y-shaped brace 36. In turn the leg of Y-shaped brace 36 is 
pivotally connected to bracket 38, which is rigidly connected to the 
two-wheeled frame 15, by means of connector 37. 
From the foregoing, it can be seen that by turning steering wheel 11, 
steering shaft 10 is turned which causes the end of tilt fork 26 that is 
connected to worm-gear-nut 24 to be raised or lowered depending on the 
direction steering wheel 11 is turned. If steering wheel 11 is turned to 
the right, gear-worm-nut 24 ascends gear-worm 12 which in turn causes tilt 
fork 26 to be raised forcing frame 15 to be tilted to the right pivoting 
on connectors 23 and 37. Alternately, if steering wheel 11 is turned to 
the left, gear-worm-nut 24 descends gear-worm 12 which in turn causes tilt 
fork 26 to be lowered forcing frame 15 to be tilted to the left pivoting 
on connectors 23 and 37. The tilting of frame 15 simultaneously causes 
front wheel 31 to be turned by means of adjustable guide rod 29 which at 
one end is connected to front wheel subassembly 30 and at the other end to 
guide bar 31 of L-shaped lower cross member 17 which is rigidly connected 
to frame 15 but pivotally connected with connector 23 to front axle 22. 
Although the three-wheeled vehicle depicted in FIG. 1 is pedal powered, it 
is readily apparent that in addition to having the rear wheel driven by 
circular pedaling means, one or both front wheels could be mechanically 
driven such as by a d.c. motor deriving its energy from a battery source. 
For example, a d.c. motor could be affixed to each of the front wheel 
subassembly 30 and drive a front wheel utilizing belt, gear or chain 
drive. The battery would be affixed to front axle 22. 
The foregoing embodiment would be used for a slower moving vehicle whereby 
road shock can be absorbed by the spring designed as a part of front fork 
18 as shown in FIG. 3. However a faster moving vehicle, in order to lessen 
the amount of road shock transmitted to the driver, requires that front 
fork 18 incorporate shock absorbing means. 
Another embodiment of the invention for use in a higher speed vehicle, such 
as a motorcycle, is shown in FIG. 5 having shock absorbing spring 40 
integrally constructed as part of front fork 18. In order to accomodate 
the vibrational changes to front fork 18 caused by road shock, relief is 
provided to steering shaft 10 by separating it into upper shaft 10A and 
lower steering shaft 10B. Lower steering shaft 10B is rotatably secured to 
L-shaped lower cross member 17 by means of connector 20 and worm-gear 12 
is rigidly secured to lower steering shaft 10B by means of set screw 13. 
Worm-gear-nut 24, whose inner diameter is slightly larger than the outer 
diameter of worm-gear 12 which it encircles, engages worm-gear 12 by means 
of groove follower pin 25 and in addition groove follower pin 25 pivotally 
connects one tine of tilt fork 26 at its upper forked end to worm-gear-nut 
24. Connector 27 pivotally connects the other tine of tilt fork 26 to 
worm-gear-nut 24. At its lower end tilt fork 26 is pivotally connected to 
one extremity of front axle 22 by means of connector 28. Pivotally 
connected to the upper end of guide bar 21 is adjustable guide rod 29 
which in turn is pivotally connected to front wheel subassembly 30 located 
at the other extremity of front axle 22. 
Upper steering shaft 10A is slotted to provide key way 41 and in turn the 
upper part of worm-gear 12 contains key 42 that fits key way 41. Any 
vibrational movement transmitted to a solid steering shift is relieved by 
having a two-piece steering shaft wherein upper steering shaft 10A is 
rotatably and slidably connected to lower steering shaft 10B. The 
remainder of the assembly is as a-fore-described. 
Although the teachings of this invention have herein been discussed with 
reference to specific embodiments, it is understood that these are by way 
of illustration only and that others may wish to utilize this invention in 
different designs or applications.