Abstract: An exercise machine includes a frame, a motor/generator mounted on the frame and switched between a motor mode and a generator mode, a control unit connected with the motor/generator for activating the motor/generator in the motor mode, and two cranks connected with the motor/generator, wherein the cranks are driven via the motor/generator in the motor mode and drive the motor/generator in the generator mode. In an aspect, the exercise machine includes two pedals each attached to one of the cranks. In another aspect, the exercise machine includes two cranes pivotally mounted on the frame and two skis each including an end pivotally connected with one of the cranes and an opposite end pivotally connected with one of the cranks.

Abstract: A chuck device includes a body having a slot in a first end thereof and a hole is defined radially in the body and communicates with the slot. A spring is mounted to the body and is biased between a stepped shoulder on the body and a movable clamp connected to the body. A connection rod is connected to a second end of the body. A positioning pin is movably inserted in the hole and an end of the positioning pin extends from the hole and has a tapered periphery. A sleeve is slidably mounted to the body and has a first tapered inner periphery for being matched with the tapered periphery of the positioning pin. A second tapered inner periphery is defined in a second end of the sleeve so as to push the movable clamp when sliding the sleeve by compressing the spring.