Transmission shift rail interlock

A shift rail interlock mechanism (18) for a transmission having a plurality of parallel shift rails (16a,16b,16c) is operative to inhibit movement more than one shift rail from its neutral position at a given time. The interlock mechanism includes a support member (20) which supports the rear ends of the shift rails for axially shiftable movement along their respective axes. The support member (20) has an aperture (30) formed therein which extends transversely to and intersects the shift rails. A separate interlock pin (31,32) is slideably mounted within the aperture between each pair of shift rails. Each of the interlock pins is provided with tapered end portions (31b,31c) defining end surfaces (31d,31e) engageable with end surfaces of adjacent pins. Each of the shift rails (16a,16b,16c) is provided with a separate notch (933a,33b,33c) for receiving the tapered end portion of at least one of the interlock pins and which is in transverse alignment with the notches of the other shift rails when the transmission is in a neutral position. Movement of any one of the shift rails from its neutral position causes the notch of the shifted rail to engage the tapered end portion of one of the interlock pins such that the pin is moved axially within the aperture. The shifted rail secures the interlock pins in a predetermined fixed position within the notches of the other shift rails to prevent the other shift rails from moving from their neutral position until the shifted rail has been returned a neutral position.