Transmission system for atv

A transmission system adapted to be mounted to an engine of an all-terrain vehicle (ATV), said transmission system comprising:

• a transmission unit that includes two driving modules spaced apart from each other in a front-rear direction, one of said driving modules being adapted to be connected to and driven by the engine, each of said driving modules including
• a differential, and
• two axles extending away from each other from said differential and perpendicular to the front-rear direction, said differential including a differential lock that is operable to switch said differential between a lock state, where said axles are driven to rotate at the same speed, and an unlock state, where said axles are allowed to rotate at different speeds;
• and
• a switching unit that includes two differential switching mechanisms, each of said differential switching mechanisms being connected to said differential of a respective one of said driving modules for switching said differential between the lock state and the unlock state, each of said differential switching mechanisms including
• a bifurcate fork that is connected to said differential of the respective one of said driving modules, and that has an elongated groove being elongated in the front-rear direction,
• a connecting pin that is parallel to said axles, that extends through said bifurcate fork, and that is connected fixedly to said differential lock of said differential of the respective one of said driving modules, said bifurcate fork being movable along said connecting pin,
• an actuating shaft that includes:
• a first portion extending into said elongated groove of said bifurcate fork;
• and
• a second portion connected co-rotatably to said first portion and extending away from said elongated groove in an up-down direction that is perpendicular to the front-rear direction and said axles, and
• an actuating motor that is connected to said second portion of said actuating shaft for driving said second portion to rotate, thereby driving said bifurcate fork to move along said connecting pin via connection between said elongated groove and said first portion of said actuating shaft and switching said differential of the respective one of said driving modules between the lock state and the unlock state.