Abstract: A connecting mechanism includes a transmission shaft, an adjustment member, a transmission member, a key, and a fastening member. The transmission shaft forms a first threaded portion and a second threaded portion, and axially defines an assembly groove between the two threaded portions. An adjustment member receives the first threaded portion. The transmission member is sleeved on the transmission shaft, and defines a receiving groove. The key is wedge-shaped. The key is partially received in the assembly groove of the transmission shaft, and partially received in the receiving groove of the transmission member. The fastening member engages the second threaded portion, and drives the key to resist the adjustment member.