A hydraulic control type automatic transmission includes at least one shift valve (131, 132) which operates in accordance with a predetermined relation between the vehicle speed and the engine load to selectively supply hydraulic pressure to a plurality of friction elements (104, 105, 106, 107) to engage...http://www.google.fr/patents/US4531433?utm_source=gb-gplus-shareBrevet US4531433 - Hydraulically controlled automatic transmission
