A single unit of the new deployment system includes a housing to which an
electric drive motor is externally mounted. The deployment system for
each vehicle requires at least a pair of deployment units: one each for
right and left wheels. Each unit includes a reversible electric drive
motor having an armature shaft; an intermediate drive shaft; a worm
axially affixed to the intermediate drive shaft; an output shaft; a shock
damper affixed to the output shaft; a worm gear affixed to the shock
damper, the worm gear meshing with the worm, and providing rotational
locking for said output shaft; and a deployment arm coupled to the output
shaft, the deployment arm having rotatably mounted thereto a friction
drive disc, said friction drive disc having peripherally attached thereto
a plurality of chain segments. Torque applied to the output shaft by the
electric motor is limited either by a spring-loaded clutch axially
mounted on the intermediate drive shaft or by a circuit which limits
current drawn by the electric drive motor to a preset maximum.