Page:Popular Science Monthly Volume 89.djvu/444

 A Six-Wheel Automobile

��Centrally Located Horizontal »■ Wrist Plnte

��A MICHIGAN inventor has worked out a steering mechanism for four wheels of a six-wheel vehicle. His invention is unique in that it embodies no radical changes from existing methods now in use, but rather distributes the applicable use of those methods. He has found that there are special advantages in driving all four wheels where soft tires are used, as beyond a certain limit the tractive strain on such tires, especially pneumatic tires, is so destructive that it is impracticable to drive with two wheels for a load of more than four or five persons.

Furthermore, he claims that another ad- vantage in a "double" or four-wheel drive where all four wheels are steered, is that the rear wheels always fol- low the track of the front wheels. In mov- ing forward or back- ward, turning either to right or left, it is impossible for the rear wheels to get out of the track of those in front. If the front wheels clear an obstruction the driver knows that the rear wheels will clear also and need give them no concern.

In the accompanying drawing is shown a vehicle frame having six wheels. The front and rear wheels are steering wheels, which are deflected by ihe steering-lever. The centrally located pair of wheels are not steering wheels and always remain in the same planes relatively to the body. When the steering wheels are deflected to steer the vehicle to the right they will follow one another in circles, while the central wheels will turn as on pivots in circles a few inches within the steering wheel circles.

��Steering Wheel Hub

���Steering Wheel Hub

��How the Four Wheels of a Six- Wheel Automobile Are Steered

��The interesting features of the mech- anism are the hubs of the four steering wheels, the centrally located horizontai wrist-plate with which the steering rods are connected, and the T-joints on the central axle. The hub of each steering wheel consists of a tubular body with which the driving axle is attached by a uni- versal joint arranged in the central plane of revolution of the wheel, and permitting • the wheel while receiving the rotating power of the driving axle to oscillate freely in every direc- tion. The inner end of the tubular body of the hub engages with a sway-block having a horizontal slot sliding on the axle. This holds the wheel rigidly up- right, while allowing it to oscillate to conform to the direction of motion of the vehicle. The centrally- loca- ted horizontal wrist- plate which is attached to the steering rods is composed of a cam- plate, a double cam- plate having a ball and socket bearing and numerous other acces- sories too intricate to describe here, all of which give to the four-wheeled steering mechanism the ad- vantages of a sensitive and automatically locked movement in all maneuvering required in steering on ordinary straight roads, and accelerated as it approaches extreme swing right or left.

To proxide for unevenness in the road it is necessary to pivot the frame at the central axle. To this end the reaches are separately journaled with T-joints on the central axle, which permits any individual axle to move vertically and yet maintains the axle rigidly against lateral movement.

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