How does the rotating ring of a stationary mechanical seal rotate?

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In a stationary mechanical seal, the rotating ring is directly fixed to the shaft (shaft sleeve) and rotates together with it; several methods are commonly used for such fixation. 1. Nut fixation (see Figure 3). This structure requires a boss on the shaft, the moving ring to have an “L”-shaped cross-section; after the moving ring is installed, it is held in place by a short sleeve, which is then tightened with a circular nut. To prevent the medium from leaking along the moving ring, seal rings are provided at the end faces of the moving ring and the shaft sleeve boss. 2. Screw drive, (see Figure 38). The rear end face of the moving ring is drilled with screw holes and threaded; the shaft sleeve has a flange, and screws are used to connect the moving ring to the flange of the shaft sleeve. A gasket is placed in between to prevent the medium from leaking between the moving ring and the shaft sleeve. 3. Thimble drive (Figure 39). This structure actually adds a transmission sleeve, which is fixed to the shaft using set screws; the moving ring is connected to it via pins. Sealing rings are provided between the transmission sleeve and the shaft, as well as between the moving ring and the transmission sleeve. This moving-ring structure is relatively complex, but its floating nature has been improved. 4. Pin drive (Figure 40). This type of transmission eliminates the transmission sleeve shown in Figure 39; the moving ring and the shaft are connected by pins, with their axial position determined by steps. Clearly, there is no rigid connection between the moving ring and the shaft, resulting in good flexibility.