WALKING MACHINES
Farm operations must be conducted on loose and broken surfaces for which the ordinary wheeled vehicle is unfitted. In some cases broad wheels are used to keep them from sinking into the soil and they are furnished with cleats so as to give them a good grip on the ground, but long ago it was realized that if the horse was to be completely displaced on the farm a more adaptable form of locomotion than that of wheels must be furnished. Inventors sought to make machines that would walk. One interesting machine of this class which met with a certain degree of success attempted to combine walking and rolling. Large wheels were used which were provided with a series of feet or tread plates connected by knuckle joints to the wheel rims. As the wheels revolved, these treads came successively into contact with the ground and the machine actually walked on its feet. The feet were broad enough to prevent the machine from sinking into the ground and they adapted themselves to inequalities in the surface. Instead of having to roll over a rock that lay in its path the machine would plant its feet on the rock and lift itself over.
A very curious machine of the walking type has been developed for excavating machines that operate in soft swampy ground. The machine actually walks over surfaces that a light carriage could not negotiate. It consists of a large central turntable flanked on each side by a pair of broad and long tread plates which serve as feet. When the dredge is to be moved, it plants the feet on the ground, lifts up the turntable, moves it forward, and sets it down again; then the feet are lifted, moved forward, and planted on the ground again while the turntable is moved forward again. When it is desired to make a turn the machine is swiveled around to the desired direction while sitting on the turntable with its feet raised clear of the ground. Of course the speed of such a machine is very low, but transportation is of secondary consideration. The main purpose of the machine is to excavate ditches in soft ground and only occasionally does it have to move its position. The turntable provides a broad base that distributes the load over a comparatively large area which prevents the machine from sinking into the mud, and if it should sink into a soft spot it lifts itself out vertically instead of having to roll out.