rocker

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rocker

1. any of various devices that transmit or operate with a rocking motion
2. a steel tool with a curved toothed cage, used to roughen the copper plate in engraving a mezzotint
3. 
a. an ice skate with a curved blade
b. the curve itself
4. Skating
a. a figure consisting of three interconnecting circles
b. a half turn in which the skater turns through 180?, so facing about while continuing to move in the same direction

rocker

[′räk·ər]
(civil engineering)
A support at the end of a truss or girder which permits rotation and horizontal movement to allow for expansion and contraction.
(graphic arts)
A type of chisel, with a sharp beveled edge, used in mezzotint engraving; it is set on the surface of a copper plate and rocked back and forth to produce a rough grain, which, when printed, produces a velvety black.
(mining engineering)
A small digging bucket mounted on two rocker arms in which auriferous alluvial sands are agitated by oscillation, in water, to collect gold.
(ordnance)
Movable, built-in support in a field gun carriage, between the trail and the cradle, that allows changes in elevation to be made without disturbing the angle of position setting.