Running power transmission mechanism for a vehicle

A running power transmission mechanism for a vehicle for transmitting drive power from a driving source to steering and steered wheels, which are respectively disposed closer to first and second sides of the vehicle in a fore and aft direction thereof, comprising:

• a main-transmission device having a steering-wheel drive output shaft for outputting to the steering wheels drive power, which is synchronized with drive power outputted to the steered wheels;
• steering-wheel speed change device for non-stepwisely changing the speed of drive power inputted via the steering-wheel drive output shaft and outputting the drive power to the steering wheels, in which said steering-wheel speed change device is switchable between a standard transmission state, which outputs power enabling the steering wheels to have an average peripheral speed substantially equal to an average peripheral speed of the steered wheels, and a higher speed transmission state, which outputs power enabling the steering wheels to have an average peripheral speed higher than an average peripheral speed of the steered wheels;
• said steering-wheel speed change device including:
• non-stepwise speed change unit having an output shaft and an output adjusting member so as to output through said output shaft power with its speed non-stepwisely changed based upon an operational state of the output adjusting member, which is operated according to a steering angle of the steering wheels;
• and
• a planetary differential unit having first, second and third elements, the first and second elements designed to respectively receive power from the steering-wheel drive output shaft and power from the output shaft of the non-stepwise speed change unit, and the third element designed to output power therefrom to the steering wheels.