A transmission device, comprising: - a casing, - an input shaft rotatably mounted with respect to the casing, - an output shaft rotatably mounted with respect to the casing, - a brake between the casing and the output shaft, the brake being movable between a disengaged configuration in which the brake allows rotation of the output shaft with respect to the casing and a engaged configuration in which the brake prevents rotation of the output shaft with respect to the casing, - a first coupling assembly comprising a first input part secured in rotation to the input shaft, a first output part secured in rotation to the output shaft, and a first coupling mechanism between the first input part and the first output part, the first coupling mechanism being configured to move the first input part with respect to the first output part between a first coupling position when the torque transmitted between the first input part and the first output part is lower than a first threshold, and a second coupling position when the transmitted torque is greater than the first threshold, characterized by - a second coupling assembly comprising a second input part secured in rotation to the first input part and a second output part secured in rotation to the output shaft, and a second coupling mechanism between the second input part and the second output part, the second coupling mechanism being configured to move the second input part with respect to the second output part between a first coupling position when the transmitted torque between the second input part and the second output part is lower than a second threshold, the second threshold being lower than the first threshold, and a second position when the transmitted torque is greater than the second threshold, wherein the movement of the second input part with respect to the second output part towards the second position causes movement of the brake towards the engaged configuration. - a casing, - an input shaft rotatably mounted with respect to the casing, - an output shaft rotatably mounted with respect to the casing, - a brake between the casing and the output shaft, the brake being movable between a disengaged configuration in which the brake allows rotation of the output shaft with respect to the casing and a engaged configuration in which the brake prevents rotation of the output shaft with respect to the casing, - a first coupling assembly comprising a first input part secured in rotation to the input shaft, a first output part secured in rotation to the output shaft, and a first coupling mechanism between the first input part and the first output part, the first coupling mechanism being configured to move the first input part with respect to the first output part between a first coupling position when the torque transmitted between the first input part and the first output part is lower than a first threshold, and a second coupling position when the transmitted torque is greater than the first threshold, characterized by - a second coupling assembly comprising a second input part secured in rotation to the first input part and a second output part secured in rotation to the output shaft, and a second coupling mechanism between the second input part and the second output part, the second coupling mechanism being configured to move the second input part with respect to the second output part between a first coupling position when the transmitted torque between the second input part and the second output part is lower than a second threshold, the second threshold being lower than the first threshold, and a second position when the transmitted torque is greater than the second threshold, wherein the movement of the second input part with respect to the second output part towards the second position causes movement of the brake towards the engaged configuration.