Hydraulic circuit system for automatic transmission

Claim 1

A hydraulic circuit apparatus for an automatic transmission including a plurality of friction engaging elements and a planetary gear set, said hydraulic circuit apparatus including: a pressurized hydraulic fluid source; a regulator valve connected to said source via first fluid conduit means; hydraulic power cylinders connected to said friction engaging elements and in fluid communication with a regulated fluid output of said regulator valve via second fluid conduit means; hydraulic control means including a governor valve, a throttle valve and at least one shift valve, said hydraulic control means being in fluid communication with said regulated fluid output of said regulator valve via third fluid conduit means; fourth fluid conduit means connected between said regulator valve and said torque converter for providing fluid flow therebetween; valve means associated with said regulator valve for selectively supplying fluid from said regulator valve to said fourth fluid conduit means when said fluid source provides fluid pressure exceeding a predetermined value; fifth bypass fluid conduit means connected between said first and fourth fluid conduit means; and restriction means in said fifth bypass fluid conduit means, said restriction means being sized for permitting a predetermined fluid flow rate therethrough at a fluid pressure below said predetermined value.