pantograph

noun

1. Also pantagraph. an instrument for the mechanical copying of plans, diagrams, etc., on any desired scale.
2. Electricity. a device usually consisting of two parallel, hinged, double-diamond frames, for transferring current from an overhead wire to a vehicle, as a trolley car or electric locomotive.

noun

1. an instrument consisting of pivoted levers for copying drawings, maps, etc, to any desired scale
2. a sliding type of current collector, esp a diamond-shaped frame mounted on a train roof in contact with an overhead wire
3. a device consisting of a parallelogram of jointed rods used to suspend a studio lamp so that its height can be adjusted