Abstract: Arrangement for preventing incorrect shifting in a gearbox having a base portion and a two-speed range portion has a gear selector mechanism coupled to a shift unit and comprising a first blocking system coordinated with the shift unit of the range portion and the gear selector mechanism of the base portion to block shifting in the base portion during shifting of the shift unit in the range portion, and a second blocking system coordinated with means for sensing the rotational speed of the output shaft and with the gear selector mechanism of the base portion to prevent shifting to certain gears in the base portion when the rotational speed of the output shaft exceeds certain values. First and second blocking systems have a common blocking device. The first system has apparatus sensing the shifting movement of the shift unit and disposed to activate the blocking device to block the gear selector of the base portion in the neutral position during shifting.

Abstract: A gearbox for motor vehicles having an input shaft with an input gear; a countershaft with a drive gear for the countershaft, said driving gear engaging the input gear; a transmission main shaft with a number of gears depending on the number of gear ratios, each of said gears being in driving engagement with an individual gear on the countershaft; a reverse shaft with a driving gear for said reverse shaft and engaging a gear on the countershaft; as well as a reverse gear engaging a gear on the main shaft. The gears on the main shaft and associated gears on the countershaft and reverse shaft can be selectively engaged to establish various driving connections between the input shaft and the transmission main shaft. At least one additional gear, disengagably journalled on the reverse shaft, engages a gear disengagably journalled on the countershaft. One of the other gears on the countershaft engages the main shaft gear which engages the reverse gear and is disengagably journalled on the countershaft.