Transmission

Claim 1

IN AN ENGINE DRIVEN TRANSMISSION, THE COMBINATION OF PLURAL DRIVE TRAINS FOR ESTABLISHING DIFFERENT DRIVE RATIOS THROUGH THE TRANSMISSION, EACH TRAIN INCLUDING A FLUID PRESSURE OPERATED DRIVE ESTABLISHING DEVICE FOR RENDERING THE RESPECTIVE DRIVE TRAIN EFFECTIVE, A FLUID PRESSURE SOURCE, CONTROL VALVING FOR CONTROLLING THE DRIVE RATIO INCLUDING A MANUALLY OPERABLE DRIVE RANGE SELECTOR VALVE MOVABLE TO SELECT NEUTRAL, REVERSE, OR ANY ONE OF A PLURALITY OF FORWARD DRIVE RANGE CONDITIONS OF OPERATION, A LINE PRESSURE REGULATOR VALVE NORMALLY EFFECTIVE TO MAINTAIN A PREDETERMINED LINE PRESSURE SUPPLY TO SAID CONTROL VALVING, FLUID PRESSURE RESPONSIVE MEANS ASSOCIATED WITH SAID PRESSURE REGULATOR VALVE EFFECTIVE IN RESPONSE TO FLUID PRESSURE FOR REDUCING THE PRESSURE SUPPLIED BY SAID PRESSURE REGULATOR VALVE BELOW SAID NORMAL PREDETERMINED LINE PRESSURE, A PRESSURE DROP VALVE, PASSAGE MEANS CONTROLLED BY SAID DRIVE RANGE SELECTOR VALVE AND EFFECTIVE TO DELIVER LINE PRESSURE TO SAID PRESSURE DROP VALVE WHEN SAID DRIVE RANGE SELECTOR VALVE IS POSITIONED TO SELECT SAID NEUTRAL, REVERSE OR SAID FORWARD DRIVE RANGE CONDITION OF OPERATION, PASSAGE MEANS CONNECTING SAID PRESSURE DROP VALVE TO SAID FLUID PRESSURE RESPONSIVE MEANS, AN ADDITIONAL MANUALLY OPERABLE VALVE SUPPLIED WITH LINE PRESSURE FROM SAID SOURCE, A CONTROL CHAMBER IN SAID PRESSURE DROP VALVE, PASSAGE MEANS DIRECTLY CONNECTING SAID CONTROL CHAMBER TO PRESSURE DISCHARGED BY SAID ADDITIONAL MANUALLY OPERABLE VALVE, SAID ADDITIONAL MANUALLY OPERABLE VALVE IS POSITIONED TO SELECT SAID FORWARD, REVERSE OR NEUTRAL DRIVE RANGE CONDITION OF OPERATION TO DELIVER VARIABLE PRESSURE TO SAID CONTROL CHAMBER THROUGH SAID VARIABLE PRESSURE TO SAID CONTROL CHAMBER THROUGH SAID LAST-MENTIONED PASSAGE MEANS, THE PRESSURE DELIVERED BY SAID LAST-MENTIONED MANUALLY OPERABLE VALVE BEING VARIED FROM A MINIMUM PRESSURE WHEN THE TORQUE DEMAND IS MINIMUM TO FULL LINE PRESSURE WHEN THE TORQUE DEMAND IS MAXIMUM SUCH THAT SAID PRESSURE DROP VALVE IS CONTROLLED SOLELY AS A FUNCTION OF TORQUE DEMAND WHEN SAID DRIVE RANGE SELECTOR VALVE IS POSITIONED TO SELECT SAID FORWARD DRIVE RANGE CONDITION OF OPERATION, THE PRESSURE DELIVERED BY SAID PRESSURE DROP VALVE TO SAID FLUID PRESSURE RESPONSIVE MEANS VARYING INVERSELY WITH THE CONTROL PRESSURE DELIVERED TO SAID PRESSURE DROP VALVE BY SAID ADDITIONAL MANUALLY OPERABLE VALVE.