balance weight

plural balance weights · alternative balanceweight

1. A weight that acts as a counterbalance.

   Most of the overhead system is of the weight-tensioned type, constant tension being automatically applied by balance weights.

   1959 June 28, “Clacton and Walton Electrification”, in Railway Magazine, page 379

   1 more example

   The firehole door is made in three sections, hinged at the top and opening inwards to form a deflector plate, in a manner similar to the door of a Southern Region "King Arthur" class 4-6-0. Its operation, assisted by balance weights, is simple.

   1961 February, 'Balmore', “Driving and firing modern French steam locomotives - Part One”, in Trains Illustrated, page 109