pumpless
adjEtymology From pump + -less.
1
Without a pump.
- Between Paris and Lyons the substation rectifiers were multi-anode units with vacuum pumps, either water- or air-cooled (the pumpless type having come later into general use on the Continent than in Britain and being first used for main-line traction in France in 1953).1963 September, “A decade of French electrification progress”, in Modern Railways, page 193: