Fric'tion-al, a.

adjective

a. Relating to friction; moved by friction; produced by friction; as, frictional electricity. Nichol.

Frictional gearing, wheels which transmit motion by surface friction instead of teeth. The faces are sometimes made more or less V-shaped to increase or decrease friction, as required.

Two diagrams show a friction tube and a pair of friction wheels. — Friction Tube. Friction Wheels.

A diagram of two friction wheels engaging one another above a pair of horizontal friction rollers. — Frictional Gearing.