Modular transmission

A transmission which can be selectively assembled from a variety of gearbox modules, each module having a housing enclosing associated gearing components such as gears, shafts, shifters and the like, characterized in that:

• a. at least a first and a second one of said gearbox modules have generally hat-shaped housings, each having a base plate, sides surrounding said base plate and an opening opposite said base plate, said base plate of said second gearbox module mounting to said first gearbox module to substantially close the opening of said first gearbox module;
• b. said first gearbox module comprising a multi-speed gearbox having:
• i. a first input shaft having a first end rotatably supported by said base plate of said first gearbox module and a second end rotatably supported by said base plate of said second gearbox module;
• ii. two free gears rotatably mounted about said input shaft;
• iii. shifters for selectively fixing said free gears for rotation with said input shaft;
• iv. a first countershaft having a first end rotatably mounted to said base plate of said first gearbox module;
• v. two fixed gears mounted to said countershaft and fixed for rotation therewith, each said fixed gear meshing continuously with a corresponding one of said free gears;
• and
• vi. a first output gear mounted to said countershaft adjacent said second end thereof and fixed for rotation therewith;
• and
• c. said second gearbox module comprising:
• i. an opening formed in said base plate of said second gearbox module through which said first countershaft extends;
• ii. a support structure for rotatably supporting a second end of said first countershaft;
• iii. a second input shaft rotatably mounted in said second gearbox module;
• and
• iv. a second input gear mounted to said second input shaft and meshing continuously with said first output gear.