The present automatic and manual transmissions in use attempt to maximize operating economy and power through a constant maintenance of power source rotational speed at the top of the power curve. These transmissions do not have high efficiency or smooth operation because they must have stepped speed ratio changes. Existing designs for continuously variable transmission lack efficiency, simplicity of operation, power transmission capability or operating speed range.

Turning one or two pairs of wheels through a complicated linkage system or pivoting the front of the vehicle against the rear commonly accomplishes the change of direction for wheeled vehicles. For vehicles on tracks or worms it is done through braking or reversing the track or worm on one side.

In all cases existing systems consist of either a complicated mechanical arrangement, resulting in high cost and maintenance, or require substantial expenditure of available power, decreasing operating efficiency.

Summary of the invention The object of this invention is an improved vehicle's propulsion system. The proposed propulsion system takes advantage of the fact that a wheel in the shape of a

hemisphere rotating around its polar axis has larger length of circumference at its major diameter than close to its tip. The radius of a hemisphere is a constant, therefore the transition from the major diameter to a minor diameter produces step less length of circumference change without changing the point of engagement between the hemisphere wheel and the ground. The hemisphere wheel on each side of the vehicle thus would be mounted on the bearing. The inside race of the bearing would have two pivot points inside the hemisphere's major diameter allowing the wheel to swing around a mounting fork. The fork is attached to the body of the vehicle or is a part of the suspension. The center of the hemisphere wheel would be connected to the driving shaft through a constant velocity device (double universal joint, flexible shaft or similar). Alternatively, each wheel can have a motor mounted on the inside race of the bearing, the shaft of the motor is then connected to the hemisphere wheel. A control lever would have a joint attachment to the inner race of the wheel bearing, perpendicular to the pivot points. Movement of the control lever would swing the hemisphere wheel around the pivot points, changing the diameter of the wheel engaged with the ground. The positions of the control levers would thus determine the vehicles speed and/or direction. By tilting the pair of hemisphere wheels in opposite directions against the pivot points of the corresponding mounting forks, the vehicles speed would be increased or decreased.

A unidirectional swing of the pair of wheels would produce a vehicles change of direction. A four-wheel vehicle can have one pair of hemisphere wheels and another pair of regular wheels or, for increased mobility, two pairs of hemisphere wheels. By swinging one pair of hemisphere wheels in opposite direction from the second pair the front and rear of the vehicle would be directed in opposite directions thus producing an extremely small turning radius. A vehicle can have multiple pairs of hemisphere wheels. The control levers for a pair of hemisphere wheels can be separate, individually controlling each wheel, or joined,

primarily for directional control, or have both joined and individual control, allowing for multiple control schemes of speed and direction.

The position of the pivot points can be moved from inside the major diameter to a location closer to the tip of the wheel. Thus, when the wheel is being tilted, the distance from the pivot points to the ground is going to decrease. This arrangement can be beneficial for providing grater stability of the vehicle in a turn It is therefore an object of the present invention to provide an improved vehicle's propulsion system which can be easily and economically produced, simple in principal, convenient in operation, sturdy in construction, highly efficient, long lasting and capable of operating under wide range of power and speed.

Brief Description of the Drawings In the accompanying drawings forming a material part of the description, there is shown: Fig. 1 shows a perspective view of the pair of hemisphere wheels employed as a propulsion system.

Fig. 2 shows a vehicle having a pair of hemisphere wheels in the front and a pair of regular wheels in the back.

Fig. 3 shows a vehicle having two pairs of hemisphere wheels.

Fig. 4 shows a perspective view of the hemisphere wheel where the pivot points are mounted on an intermediate member.

Fig. 5 shows a cross-section of the previous embodiment.

Detailed Description of the Preferred Embodiment Referring to the Fig. 1, there is shown a first embodiment of the vehicle's propulsion system comprised of a pair of hemisphere wheels where input shaft 1 is connected to the

hemisphere wheel 2 through a double universal joint 5, flexible shaft or a similar constant velocity device. The hemisphere wheel is rotating on the bearing 9, the inner race of the bearing having two pivot points 8, attached to the mounting fork 4. The bearing 9 is located at the major diameter of the hemisphere wheel. However, as is well known in the art, the bearing can be in a number of places on the hemisphere wheel and is only a matter of design.

The fork is attached to the body of the vehicle 3 or is a part of the suspension (not shown).

The fork 4 can be attached directly to the hemisphere wheel or, as well known in the art can have an intermediate member connecting the fork to the hemisphere wheel. The control lever 7 determines the angle between the hemisphere wheel and the input shaft. The lever is connected to the inner race of the bearing 9 through a pivot joint. The hemisphere wheels are engaged through friction with the ground. As input shaft 1 is being driven by an outside source of power such as an engine or a motor, it is rotating the hemisphere wheel 2 with the same speed as the shaft through a constant velocity device 5. The speed of the wheel is the same as the input shaft regardless of the angle between the wheel and the shaft.

Each wheel can also be rotated by a motor 6 mounted on the inside race of the bearing, the shaft of the motor is then connected to the hemisphere wheel. The control lever 7 is operated by an unspecified positioning device, such as, for example, a hydraulic cylinder or a pneumatic cylinder or an actuator. It can, also, be controlled manually. The position of the control lever 7 is determining the angle between the wheel 2 and the shaft 1. When this angle is equal zero (the hemisphere wheel 2 and the shaft 1 are rotating on the same axis), the hemisphere wheel is engaged with the ground at its major diameter. The speed in this position is the highest allowed by the wheels diameter. When the control lever 7 turns the hemisphere wheel around pivot points 8 to a maximum angle allowed by the constant velocity device 5, the hemisphere wheel is engaged with the ground at it's minor diameter.

The vehicles speed in this position is the lowest allowed by the wheels diameter. Due to the

fact that the pivot points 8 lay on the diameter of the hemisphere wheel, the engagement point between the wheels and the ground being at the radius distance from the pivot points does not change regardless of the angle between the hemisphere wheel and the input shaft.

By tilting the pair of hemisphere wheels in opposite directions against the pivot points of the corresponding mounting forks, the vehicles speed would be increased or decreased. A unidirectional swing of the pair of wheels would produce a vehicles change of direction. If two wheels 2 are driven by the same shaft 1 and controlled by the same control lever 7, as the control lever 7 is moved to one side, the wheel in this direction is turned to contact the ground with the smaller diameter. At the same time the wheel on the opposite side is turned to contact the ground with the larger diameter, producing a turning motion of the vehicle.

Referring to the Fig. 3, this embodiment of the present invention's propulsion system is showing two pairs of hemisphere wheels on a four-wheel vehicle. Four control levers 7 determine the position of each hemisphere wheel separately.

FIG. 5 shows an embodiment of the present invention where the position of the pivot points 9 are moved from inside the major diameter to a location closer to the tip of the wheel.

Due to the basic nature of the invention, many modifications, variations and different applications are possible without departing from the spirit and scope of the above-described embodiments of the invention.