Land vehicles – Step or abutment ascending type vehicle – With spider-type engaging means
Patent
1982-06-08
1984-07-03
Pekar, John A.
Land vehicles
Step or abutment ascending type vehicle
With spider-type engaging means
305 1, B62B 502
Patent
active
044575262
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a wheel assembly having a frame and at least one set of wheels supporting said frame and including at least three wheels which are mounted on a holder equidistantly around the periphery thereof.
It is a well-known fact that it is difficult and often impossible to pull or push a loaded wheeled carriage, for instance a wheelbarrow, sack trolley, pram etc., on an uneven base, such as stony ground, steps etc. Unsuccessful attempts have been made to solve this problem, for instance by means of star-shaped wheels which in each point of the star have rotatably mounted wheels. The same problem is encountered in driven carriages, in particular cross-country vehicles in which attempts have been made to improve the performance by increasing the wheel size.
The object of the present invention is to solve the above defined problem and provide a wheel assembly which permits, for instance, pulling a heavily loaded sack trolley provided with such a wheel assembly over a curb stone, up a staircase etc. This object is achieved in that the holder is rotatably mounted around the periphery of a circular bearing means whose centre axis coincides with the axis of rotation of the holder, and in that the frame is connected to the circular bearing means at a radial distance from said centre axis.
When during running of the trolley the wheels of such a wheel assembly encounter such an obstacle that the rolling movement of the wheel is arrested, the point of connection between the trolley and the bearing means will start rotating relative to the centre of the bearing means, which causes shifting of the centre of gravity, whereby the topmost wheel will be tilted downward towards the obstacle to bear on the upper side thereof, whereupon the continued movement of the trolley will take place with the last-mentioned wheel rolling on the base.
The invention will be described in greater detail hereinbelow with reference to the accompanying drawings showing various embodiments.
FIG. 1 in side elevation shows a simple application of the invention.
FIG. 2 shows a sack trolley provided with a wheel assembly of the type shown in FIG. 1.
FIG. 3 shows a wheel assembly with driven wheels, and
FIG. 4 is an end view of the wheel assembly in FIG. 3.
The wheel assembly shown in FIG. 1 consists of a holder 10 in the form of an equilateral triangle. Adjacent the points of the holder 10, wheels 11 of equal size are mounted by means of journals 12. The holder 10 has a circular central opening in which a bearing means 13 in the form of a planar disc is mounted, for instance by means of flanges on the opposite sides of the disc which are of a diameter greater than that of the opening of the holder. If so desired, the bearing means 13 can be provided with friction-reducing means, for instance in the form of ball bearings, around its peripheral surface facing the wall of the opening of the holder. As seen in FIG. 1, the wheel assembly consisting of the holder 10 and the wheels 11 has an axial centre line on which the centre C of the bearing means 13 is situated. An axle 14 is fixedly connected to the bearing means 13 at a location spaced from the centre C of the bearing means.
As appears from FIG. 2, two wheel assemblies of the type shown in FIG. 1 can be mounted on a sack trolley by means of the axle 14. When the trolley is run and encounters for instance a curb, one wheel 11 of each assembly will strike the curb stone and the rolling movement will be stopped. Continued force exertion on the sack trolley will then cause the bearing means 13 to rotate as a result of the connection of the axle 14 with the bearing means at a distance from the centre C thereof. Thus, if a force is exerted to the left in FIG. 1, the means 13 will rotate clock-wise, resulting in a shifting of the line of force so as to increase the leverage, such that when the axle has rotated clock-wise slightly more than a quarter of a revolution, the holder 10 will start tilting to the left, whereby the topmost wheel 11 in FIG. 1 is pivoted downwards on to the to
REFERENCES:
patent: 1887427 (1932-04-01), Porcello
patent: 2363636 (1942-02-01), Bloch et al.
patent: 3283839 (1966-11-01), Brown et al.
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