Also, on double ended trams, they eliminate the need to manually turn the trolley pole when changing direction, and eliminate the need for wire frogs to make sure the pole goes in the correct direction at junctions.
Also, on double-ended trams, they eliminate the need to manually turn the trolley pole when changing direction. The use of pantographs (or bow collectors) exclusively also eliminates the need for wire frogs (switches in the overhead wiring) to make sure the pole goes in the correct direction at junctions.