A hydraulic pressure distributor includes a low control valve, an N-R control valve, a line pressure control switch valve, a first fail-safe valve controlled by control pressure supplied from the low control valve and from the second pressure control valve, the first fail-safe valve undergoing port conversion...http://www.google.se/patents/US6394926?utm_source=gb-gplus-sharePatent US6394926 - Powertrain for automatic transmission and hydraulic control system for controlling the same
