Abstract: A rotary driving mechanism includes a support stand, an air feeding assembly, and a driver. The air feeding assembly includes a bearing base, a rotating member, two first ventilating joints, and two second ventilating joints. The bearing base is coupled to the support stand and defines an inner circular surface. The rotating member is rotatably received in the bearing base and resists the inner circular surface. The rotating member defines two circular grooves at an outer periphery thereof and two channels therein. Each circular groove is in fluid communication with one of the channels. The first ventilating joints are coupled to the bearing base and respectively in fluid communication with the circular grooves. The second ventilating joints are coupled to the rotating member and respectively in communication with the channels. The driver is coupled to the rotating member and in communication with the second ventilating joints.

Abstract: A rotary driving mechanism includes a support stand, an air feeding assembly, and a driver. The air feeding assembly includes a bearing base, a rotating member, two first ventilating joints, and two second ventilating joints. The bearing base is coupled to the support stand and defines an inner circular surface. The rotating member is rotatably received in the bearing base and resists the inner circular surface. The rotating member defines two circular grooves at an outer periphery thereof and two channels therein. Each circular groove is in fluid communication with one of the channels. The first ventilating joints are coupled to the bearing base and respectively in fluid communication with the circular grooves. The second ventilating joints are coupled to the rotating member and respectively in communication with the channels. The driver is coupled to the rotating member and in communication with the second ventilating joints.

Abstract: A holding device includes a main body defining a channel, a supporting assembly coupled to the main body, a plurality of pistons positioned on the main body, and an adjusting assembly positioned in the main body. The substance channel includes a main channel and a plurality of first sub-channels defined from a side of the main channel and communicating with an outside. An end of each piston received in a corresponding first sub-channel, the other end coupling to the supporting assembly. The adjusting assembly is received in an end of the main channel capable of being inserted into the main channel. The plurality of pistons is configured to drive the supporting assembly to move away from the main body.