Abstract: A gravity biased constant response pantograph is disclosed. A counterweight is used to lift a collector towards an overhead conductor. A constraint mechanism constrains movement of the collector to remain substantially vertical thru the entire range of working travel. The counterweight provides a driving force via the force of gravity. A lift mechanism suitable for receiving the driving force drives a travelling assembly upwards towards the overhead conductor. The travelling assembly can be realized combining various types of collectors and masts. The counterweight is provided in two portions to accommodate various combinations of masts and collectors. By further trimming the weight of the counterweight, the amount of constant response force acting on the travelling assembly can be precisely pre-determined to be substantially constant throughout the entire range of travel of the travelling assembly.