Definition of "springless"

[…] Nos. 6166 and 6168 were fitted with Caprotti valves in 1929, and 6167 with a new springless type in 1938; […]

1939 July, Cecil J. Allen, “British Locomotive Practice and Performance”, in Railway Magazine, page 27

All the movements of the man and the woman were slow and steady; their springless feet padded flatly; their backs and shoulders were straight.

1941, Emily Carr, chapter 11, in Klee Wyck‎

All the old pattern rolling stock was withdrawn in 1888 as it had wheels which ran loose on the axles and was, for the most part, springless.

1947 May and June, “Notes and News: The Wenford Bridge and Ruthern Bridge Branches, Southern Railway”, in Railway Magazine, page 182