Power-assisted gear-shift mechanism for manual transmission

A power-assisted gear-shift mechanism for a manual transmission in an automotive vehicle, comprising:

• a lateral casing mounted on a housing of said transmission;
• a first lateral shaft rotatably mounted within said lateral casing and being operatively connected to a manual shift lever to be rotated in shifting operation of said shift lever;
• and
• a second lateral shaft in the form of a hollow shaft rotatably and axially slidably mounted on said first lateral shaft and being operatively connected to said manual shift lever to be axially moved in selecting operation of said shift lever, said second lateral shaft being integrally provided with a shift-and-select lever which extends into an interior of said transmission housing to be selectively engaged with a plurality of shift heads in axial movement of said second lateral shaft;
• wherein the power-assisted gear-shift mechanism is associated with a hydraulic power cylinder assembly which includes a cylinder casing integrally connected to one end of said lateral casing and extending along one side of said transmission housing, said cylinder casing being provided with an inlet port for connection to a source of hydraulic pressure and an outlet port for connection to a fluid reservoir;
• a hollow piston shaft having a piston part axially slidably disposed within said cylinder casing to subdivide an interior of said cylinder casing into two fluid chambers, said piston shaft being operatively connected at one end thereof to said second lateral shaft to cause rotation of said second lateral shaft in axial movement thereof;
• and a valve spool axially slidably disposed within said piston shaft and being operatively connected at one end thereof to said first lateral shaft to be displaced by rotation of said first lateral shaft, said valve spool cooperating with the piston part of said piston shaft for selectively directing hydraulic fluid under pressure from said pressure source to said fluid chambers through said inlet port in accordance with relative displacement of said piston shaft and said valve spool.