A collapsible, adjustable frame mounted on an electric streetcar that contacts the overhead power cables. Pantographs replaced the trolley pole¹ on streetcars in the 1920s (which is why Webster 1913 hasn't heard of this usage).

1. The word trolley originally referred to the wheel or brush the contacted the overhead wire, and only later came to mean the entire car.

Pan"to*graph (?), n. [Panto- + -graph: cf. F. pantographe.]

An instrument for copying plans, maps, and other drawings, on the same, or on a reduced or an enlarged, scale.

Skew pantograph, a kind of pantograph for drawing a copy which is inclined with respect to the original figure; -- also called plagiograph.

© Webster 1913.