Hydraulic shift for motor vehicle transmission

A hydraulic apparatus for remotely operating a motor vehicle automatic transmission mode select arm on the transmission casing, said apparatus comprising a master cylinder in the form of an axially elongated tubular first housing, a first piston axially reciprocable in said first housing and separating said first housing into a first chamber on one side of said first piston and a second chamber on the other side of said first piston, an input rod connected at an end to said first piston, a remotely located slave cylinder in the form of a second housing, a second piston reciprocable in said second housing and separating said second housing into a first chamber on one side of said second piston and a second chamber on the other side of said second piston, a first flexible conduit placing said first chamber of said master cylinder in fluid communication with one of said chambers of said slave cylinder, a second flexible conduit placing said second chamber of said master cylinder in fluid communication with the other of said chambers of said slave cylinder, an output rod member linearly displaceable by said second piston in said slave cylinder, and hydraulic fluid filling said master cylinder first and second chambers, said slave cylinder first and second chambers and said first and second flexible conduits, whereby linear displacement of said master cylinder input member as controlled by an operative mode transmission selection lever causes a corresponding linear displacement of said slave cylinder output member to operate a mode selection arm on the casing of the transmission, a reservoir of fluid attached to said master cylinder, a first passageway placing said reservoir in fluid communication by gravity with said master cylinder first chamber, a second passageway placing said reservoir in fluid communication by gravity with said master cylinder second chamber, and valve means in each of said passageways allowing free unrestricted flow of fluid from said reservoir to said chambers and preventing reverse flow of fluid from one of said chambers to said reservoir upon motion of said master cylinder piston causing a sudden increase of fluid pressure in said one of said chambers, said valve means allowing flow of fluid through each of said passageways from each of said chambers upon increase of volume of fluid in each of said chambers, said passageways being spaced apart axially by a distance greatly exceeding the extent of axial sealing engagement of said master cylinder piston with said master cylinder housing so that said master cylinder piston may reciprocate in said master cylinder housing over a wide range of axial movement corresponding to a plurality of positions of the transmission selection lever without blocking either of said passageways.

A hydraulic apparatus for remotely operating a motor vehicle automatic transmission mode selection arm on the transmission casing, said apparatus comprising a master cylinder in the form of an axially elongated tubular first housing, a first piston axially reciprocable in said first housing and separating said first housing into a first chamber on one side of said first piston and a second chamber on the other side of said first piston, an input rod connected at an end to said first piston and connected at its other end to an end of an arm attached to an operative mode shift lever whereby angular displacement of the shift lever causes linear displacement of said input rod, a remotely located slave cylinder in the form of a second housing, a second piston reciprocable in said second housing and separating said second housing into a first chamber on one side of said piston and a second chamber on the other side of said second piston, a first flexible conduit placing said first chamber of said master cylinder in fluid communication with one of said chambers of said slave cylinder, a second flexible conduit placing said second chamber of said master cylinder in fluid communication with the other of said chambers of said slave cylinder, an output rod member linearly displaceable by said second piston in said slave cylinder, means at the end of said output member connecting said output member to the transmission mode selection arm, and hydraulic fluid filling said master cylinder first and second chambers, said slave cylinder first and second chambers and said first and second flexible conduits, whereby linear displacement of said master cylinder input member as controlled by said operative mode shift lever causes a corresponding linear displacement of said slave cylinder output member to operate the transmission mode selection arm on the transmission casing, a reservoir of fluid attached to said master cylinder, a first passageway placing said reservoir in fluid communication by gravity with said master cylinder first chamber, a second passageway placing said reservoir in fluid communication by gravity with said master cylinder second chamber, and valve means in each of said passageways allowing free unrestricted flow of fluid from said reservoir to said chambers and preventing reverse flow of fluid from one of said chambers to said reservoir upon motion of said master cylinder piston causing a sudden increase of fluid pressure in said one of said chambers, said valve means allowing flow of fluid through each of said passageways from each of said chambers upon increase of volume of fluid in each of said chambers, said passageways being spaced apart axially by a distance greatly exceeding the extent of axial sealing engagement of said master cylinder piston with said master cylinder housing so that said master cylinder piston may reciprocate in said master cylinder housing over a wide range of axial movement corresponding to a plurality of positions of the mode selection arm on the transmission casing without blocking either of said passageways.