Transmission for agricultural tractor

A transmission for an agricultural tractor comprising a main transmission casing, a main speed change means disposed within said main transmission casing, said main speed change means including first, second, and third shift gears for main speed changes, a constant drive gear for power take-off disposed within said main transmission casing, said first, second, and third shift gears and said constant drive gear mounted within said main transmission casing on a main common shaft supported at opposite ends by said main transmission casing, said constant drive gear fixed in the axial direction for relative rotation on said common shaft and said first, second, and third shift gears being splined on said common shaft for axial movement relative thereto, an opening in one side of said main transmission casing, said first, second, and third shift gears and said constant speed gear being disposed in relative positions in proximity to said opening in said main transmission casing and exposed thereby;

• an auxiliary speed change means supported within an auxiliary transmission casing, said auxiliary transmission casing removably secured to said main transmission casing relative to said opening therein, said auxiliary speed change means including an input gear arranged to mesh with said constant drive gear and an output gear so arranged to mesh with one of said shift gears on said main common shaft, said input gear and said output gear mounted on an auxiliary common shaft supported by said auxiliary transmission casing, said output gear being freely rotatable relative to said auxiliary common shaft and said input gear being splined to said auxiliary common shaft for rotation therewith.