unsprung

Adjective

unsprung (not comparable)

1. Not sprung.
   • an unsprung trap
2. Not supported by the suspension of a vehicle.
   • The locomotive is carried on two six-wheel bogies, the outer axles of each bogie being driven by series type d.c. motors, completely suspended to reduce the unsprung weight to a minimum.1947 January and February, “Gas Turbine-Electric Locomotive for G.W.R.”, in Railway Magazine, page 26
   • Amongst the factors peculiar to electric m.u. traction are the heavy unsprung weight of the motors (generally, the greater the weight, the worse is the riding); […].1960 February, “Letters to the Editor”, in Trains Illustrated, page 125
3. Not fitted with springs; lacking springs.
   • The Winchburgh Shale Line is of 2 ft. 6 in. gauge. The surface trucks or tubs are cuboidal metal boxes mounted on unsprung four-wheeled chassis.1958 September, Anthony A. Vickers, “The Winchburgh Shale Line”, in Railway Magazine, page 613
   • He had an unsprung trailer for the job[.]2000, Bob Foster, Birdum or Bust!, Henley Beach, SA: Seaview Press, page 169