DISPOSITIVO DI COMANDO IDRAULICO PER MANOVRARE DUE FRIZIONI FUNZIONANTI PARALLELAMENTE DI UN CAMBIO DI VELOCITA' PESANTE A PIU' MARCE

摘要

A hydraulic control system of the type disclosed in U.S. Pat. No. 3,938,410 is improved by providing a 2-3 shift valve which connects a direct passage and a throttle-containing passage to the control valve for the second clutch or brake (second-friction device) while the pressure in the first clutch or brake (first friction device) is applied to one side of the second control valve, a restoring spring acting upon the opposite side of this second control valve. This valve establishes a threshold for the pressure in the first friction device such that the direct passage is connected to the second friction device below the threshold while the throttle-containing passage is connected to the second friction device at or above this threshold.