Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

Chapter 5 Tracked Vehicle Suspensions and Drivetrains 181
Figure 5-15
fore-and-aft
Two wide tracks,
can no longer turn in place like the basic two-track layout can, yet has
more moving parts.
An unusual variation of the two-track layout is to place the two tracks
inline, one in front of the other (Figure 5-15). Stability is maintained by
making the tracks sufficiently wide, and steering is accomplished with
an articulated joint between the two tracks. The tracks have to be supported
from both sides, like on a snow mobile. Steering power is transmitted
through one or two linear or rotary actuators that are part of the
articulated joint.
This system also benefits from the trick of making the center of each
track a little lower than the ends. Since the tracks are already fore-andaft,
the bowed shape on each track does not produce any wobbling. This
system has great mobility, but like the half-track, cannot turn in place. It
would probably work very well for vehicles intended for use on snow or
sand. The two tracks could either each carry their own chassis, or a single
chassis could be attached to the universal joint with the outer ends
of the track sections suspended to the chassis with a sprung or active
suspension.
Four-Tracked Drivetrains
Adding more tracks would seem to increase the mobility of a tracked
vehicle, but there are several problems with this approach. Adding more
tracks necessarily means more moving parts, but it also usually means
making the vehicle longer. The best layout would be one that adds more