Transmission

A transmission comprising:

• a first pulley assembly rotatable about a first axis;
• a second pulley assembly spaced apart from the first pulley assembly and rotatable about a second axis;
• an endless member extending between and rotationally coupling the first pulley assembly and the second pulley assembly;
• an idler pulley engaging the endless member and rotatable about an idler axis, the idler pulley being movable between at least a first position and a second position;
• and
• a tensioner assembly coupled to the idler pulley and configured to control tension in the endless member, the tensioner assembly comprising:
• a tensioner spring having a spring axis and biasing the idler pulley towards the second position;
• and
• a tensioner arm rotatable about a tensioner axis and coupling the tensioner spring to the idler pulley, the tensioner arm defining a spring linkage that extends between the tensioner axis and a spring coupling point, where the tensioner spring is coupled to the tensioner arm, and further defining an idler linkage that extends between the tensioner axis and an idler coupling point, where the idler pulley is coupled to the tensioner arm,
• wherein a spring angle is defined between the spring axis and the spring linkage,
• an idler lock that is movable between an unlocked position and a locked position,
• wherein the idler lock secures the idler pulley in the second position when the idler lock is in the locked position, and wherein the idler lock does not secure the idler pulley in the second position when the idler lock is in the unlocked position;
• and
• wherein the idler lock comprises a locking surface for engaging the idler pulley when the idler pulley is in the second position, and further comprises an idler lock spring that biases the idler lock towards the locked position, wherein the locking surface is defined by a plane that forms an angle (Ω) with the idler linkage, and wherein the angle (Ω) and the idler lock spring are configured to automatically release the idler pulley when tension in the endless member exceeds a threshold.