Shift linkage for a tilt cab truck

Abstract

A gearshift linkage for a cab-over-engine type truck having a shift lever extending up through the cab floor enables the forward tilting of the cab on the frame, about the cab pivot axis, without disengagement of the shift linkage and without dislocation of the shift lever from the cab. In the preferred embodiment, a conventional shifter control unit is secured to the cab just below the floor, with the shift lever extending up from the control unit. The control unit is equipped to accept side-to-side movement of the shift lever and translate it into rotation of a control unit output shaft, and to accept forward and rearward movement of the shift lever and translate it into generally forward and rearward movement of the output shaft. The control unit output shaft is connected through a first universal joint to a control shaft which extends forwardly and downwardly from the cab, being connected at its other end to a specially configured universal joint. The special universal joint is at the forward end of a transmission linkage shaft which extends back to the transmission and mounted to the truck frame for both axial sliding movement and rotational movement. The specially configured universal joint is at the apex of a sharply acute angle between the control shaft and the transmission linkage shaft, and is located as close as possible to the cab pivot axis, about which the cab tilts forward on the frame. When the cab is tilted forward on its axis, all of the shift linkage remains connected. The offset of the special joint from the cab pivot axis causes the control shaft to undergo some translation relative to the shifter control unit, causing the shift lever to undergo minor changes of position not detrimental to the operation or to the shift linkage.