Dual-clutch transmission (9, 31, 32) of countershaft type of construction, comprising a main transmission and a range transmission connected downstream of the main transmission, wherein the main transmission has a first transmission input shaft, which is connected to the output side of a first powershift clutch and which is formed as a solid shaft, a second transmission input shaft, which is connected to the output side of a second powershift clutch and which is formed as a hollow shaft and through which the first transmission input shaft is led, two countershafts (VW1, VW2) which are arranged coaxially with respect to one another, wherein the first countershaft is formed as a hollow shaft and the second countershaft is led through the first countershaft, and an output shaft which is arranged coaxially with respect to the two transmission input shafts (EW1, EW2), which output shaft forms the drive shaft of the range transmission, wherein the powershift clutches (K1, K2) are connected, at the drive side, to a drive assembly, wherein, on the second transmission input shaft, there is arranged a first fixed gear which meshes with a second fixed gear on the second countershaft, wherein, on the first transmission input shaft, there are arranged a first idler gear, which can be engaged by means of a first positively locking engaging element, and a second idler gear, which can be engaged by means of a second positively locking engaging element, which idler gears mesh in each case with a third and a fourth fixed gear on the first countershaft, wherein the second engageable idler gear is selectively detachably connectable rotationally conjointly by means of the second positively locking engaging element to the first transmission input shaft or by means of a third positively locking engaging element to the output shaft of the main transmission, wherein, on the output shaft of the main transmission, there is arranged a third idler gear which can be engaged by means of a fourth positively locking engaging element which meshes with a fifth fixed gear arranged on the first countershaft, wherein the first countershaft is detachably connectable rotationally conjointly by means of a fifth positively locking engaging element to the second countershaft, and on the output shaft of the main transmission, there is arranged a sixth fixed gear which meshes with a fourth idler gear which is arranged on the second countershaft and which can be engaged by means of a sixth positively locking engaging element, wherein, to realize the reverse ratios and to form the reverse ratio gear plane, on the output shaft of the main transmission, there is arranged a fifth idler gear which can be engaged by means of a seventh positively locking engaging element and which meshes with an intermediate gear of an intermediate shaft for rotational speed reversal, which intermediate gear meshes with a seventh fixed gear arranged on the second countershaft, and wherein, for bypassing the range transmission, the second countershaft is detachably connectable by means of an engaging element (J, K) to the output of the range transmission, and wherein the range transmission is formed as a transmission of countershaft type of construction, comprising a third and a fourth countershaft (VW3, VW4), wherein the output shaft of the main transmission has, downstream of the reverse ratio gear plane viewed axially in the power flow direction during traction operation, a seventh engageable idler gear, which meshes with a ninth fixed gear of the fourth countershaft and an eleventh fixed gear of the third countershaft and which is detachably connectable by means of a twelfth positively locking engaging element to the output shaft of the main transmission, and an eighth engageable idler gear, which meshes with a tenth fixed gear of the fourth countershaft and a twelfth fixed gear of the third countershaft and which is detachably connectable by means of a thirteenth positively locking engaging element to the output shaft of the main transmission, wherein the eighth idler gear forms the output of the transmission, and wherein the third countershaft is detachably connectable by means of a fourteenth positively locking engaging element to the second countershaft.