Also camb, camm. [cf. Du. kam (MDu. cam), Ger. kamm, Da. and Sw. kam, the same word as Eng. COMB, but also applied to a ‘toothed rim or part of a wheel, teeth of a wheel,’ as in Du. kamrad, Ger. kammrad, Da. and Sw. kamhjul ‘toothed wheel, cog-wheel’; thence also mod.F. came ‘cog, tooth, catch of a wheel, sort of tooth applied to the axle of a machine, or cut in the axle, to serve to raise a pestle or forge-hammer.’ Taken into English prob. either from Du. or Fr.
The primary meaning of Teut. kambo- was ‘toothed instrument’; cf. its cognates Gr. γόμφο- tooth, peg, Skr. jambha- tusk, OSlav. ząbŭ tooth: see COMB.]
A projecting part of a wheel or other revolving piece of machinery, adapted to impart an alternating or variable motion of any kind to another piece pressing against it, by sliding or rolling contact. Much used in machines in which a uniform revolving motion is employed to actuate any kind of non-uniform, alternating, elliptical or rectilineal movement. The original method was by cogs or teeth fixed or cut at certain points in the circumference or disc of a wheel, but the name has been extended to any kind of eccentric, heart-shaped, or spiral disc, or other appliance that serves a similar purpose.
1777. Specif. W. Vicker’s Patent No. 1168. The wheel F turning a cylinder with a cam and two crankes.
1805. Specif. J. Hartop’s Patent No. 2888. Upon any axis A … apply a pin, cam, crank or curve or curves C.
1831. G. R. Porter, Silk Manuf., 269. Camms, or wheels of eccentric form.
1832. Babbage, Econ. Manuf., vi. (ed. 3), 44. If one or more projecting pieces, called cams, are fixed on the axis opposite to the end of each lever.
1858. Greener, Gunnery, 418.
1867. Athenæum, No. 2084. 440/3. An iron camb for power-looms.
1879. Cassell’s Techn. Educ., I. 407/2. Cams are variously-formed plates, or grooves, by means of which a circular may be converted into a reciprocating motion.
b. Comb., as cam-ball valve, cam-groove, cam-gear wheel, cam-shaft, cam-wheel.
1879. Cassell’s Techn. Educ., IV. 393/1. A cam-groove cut in the reverse side of the crank-plate.
1874. Knight, Dict. Mech., 435/2. The duty of the cam-wheel is to give an intermittent reciprocating motion to the bar.
