Device for the transmission of rotational power that relies on friction between the drive devices to transmit the forces.
A pair of friction discs (A and B) on parallel shafts out of line, with a traverse friction pinion on a traverse spindle (c-d′) that allows for a range of speed ratios.
Variable speed from a pair of cone pulleys, one the driver and the other driven. A double faced friction pinion is moved on the line (A,B) in contact with both cones.
Variable speed from a rocking shaft and convex discs. This is "Wright′s" driving device for sewing-machines. A is the driving shaft with convex disc. B is a band shaft that swivels by the foot pedal and kept taut or released at its different positions.
Another variable speed transmission originally design for sewing machines. A is the concave driving cone . B is the swivelling yoke carrying a friction pulley, with a band running a pair of pulleys at the swivel, one of which drives the sewing machine.
Variable speed friction drive where the speed ratio is changed by traversing the pulley from the centre of the disc wheel to the edge.
"Wright′s" model of variable speed for sewing machines. The upper shaft is fixed and is the driving shaft. The lower shaft swivels to give a variable speed ratio.
Variable motion using curved-face discs with a wheel between the drive and driven wheels that can be swivelled to control the speed ratio.
Subjects: Mechanical Engineering