Fig. 1542.
Fig. 1543.
In the annular space left between the face of pulley c and the cone b is a steel band g, [Fig. 1542], forming within a fraction a complete circle, and lined inside and out with leather, and this band is brought, by alternately expanding and contracting it, into contact with either the bore of the largest cone step of b or with the outside face of pulley c. The ends of this band are pivoted upon two pins f, which are fast in two arms e and d, in [Fig. 1542]. Arm e is fastened to the driving shaft h, and its hub has two roller studs k, [Fig. 1541], these being diametrically opposite on the said hub. The hub of arm d is a working fit upon the hub of e, and has two slots to admit the above rollers. Hub d is also provided with two studs and rollers placed midway between the studs k. These latter rollers project into the spiral slots k′ of the ring in [Fig. 1543], this ring enveloping the hub of d and being enveloped by the sleeve m, which contains two spiral grooves diametrically opposite, and lying in an opposite direction to grooves k′, [Fig. 1543]. Sleeve m is prevented from revolving by rollers on the studs o, which are screwed into the bearing bush r, and carry rollers projecting into the slots in m.
It is evident that if the ring l, [Fig. 1543], is moved endways with m, then the arms e, d, together with the band g, will be expanded or contracted according to the direction of motion of the ring, because the motion of m, by means of its spiral grooves, gives a certain amount of rotary motion to the ring l, and the spiral grooves in the ring give a certain amount of rotary motion to the arms d and e, [Fig. 1542]. When this rotary motion is in one direction the band is expanded; while when it is reversed it is contracted, and the direction of motion of shaft h is reversed.
Fig. 1544.