Shift mechanism in a manual transmission

Claim 1

In combination with a manual transmission for an automobile having a transmission casing, a shift-and-select lever shaft mounted on said transmission casing so as to move axially and rotate about its axis, a shift-and-select lever fixed to said shift-and-select lever shaft and provided with an engagement portion at its lower end for engaging with shift heads which can take two shift positions and a neutral position and provided with detent grooves at its upper end, a detent mechanism comprising: a cylindrical holder provided with an opening at its one end and removably mounted on said transmission casing such that said opening is directed towards said detent grooves; a detent ball accommodated in said holder at said opening and having a diameter greater than an inner diameter of said opening, said detent ball being in tangential contact with said holder and adapted to engage with one of said detent grooves for determining a shift position of said shift heads, said opening being provided with a ball retaining portion comprising an inwardly bent circumferential edge of said holder at said opening for allowing a part of said detent ball to project from said opening while preventing said detent ball from coming out from said opening, and said holder being installed in said transmission casing in such a manner that said detent ball is slightly lifted from said ball retaining portion when said detent ball is brought into contact with one of said detent grooves of said shift-and-select lever; a compression spring accommodated in said holder and adapted to bias said detent ball against said detent grooves; and a spring seat disposed within said holder for receiving a resilient force of said compression spring, said spring seat being slidable in and abuttable at its lowermost position against said holder in such a manner that when said detent ball engages with said detent grooves of said shift-and-select lever, said spring seat is in its lowermost position and said detent ball engages the lowermost end of said spring seat without receiving the resilient force of said compression spring.