How many transmission methods are there for the shaft sleeve and drive seat of rotary mechanical seals?

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1) Thimble drive (Figure 30). The drive seat is fixed to the shaft surface using 1–2 set screws; the structure is simple. However, during installation, the shaft sleeve must be removed from the shaft in order to tighten the set screws. This structure requires pits to be made on the surface of the shaft sleeve (at the area in contact with the set screw); otherwise, transmission failure is likely to occur during operation, and the transmission seat may shift axially. When the diameter is large and the temperature is high, simple screw drive 2) can be used – a stepped screw drive (Figure 31). To overcome the axial movement of the drive seat when using only a thrust screw for transmission, a step can be provided on the shaft sleeve; the drive seat then rests against the end face of this shaft step, preventing it from moving axially. 3) Key drive (Figure 32). The shaft sleeve has a step to provide axial positioning of the drive seat, with a key used to rotate the shaft sleeve. It features a simple structure and is easy to install; during on-site construction, the drive seat can be installed without removing the shaft sleeve. It is reliable in operation, with no transmission failure occurring during use. 4) Fork drive (Figure 33). It is an improvement based on Figure 32; the shaft sleeve still has steps, and the transmission seat is a stamped part with two small \"claws\" (shift forks) that extend into the grooves of the shaft sleeve steps to enable transmission, making its structure quite simple as well. Since it is a stamped part, the fork has a small radial dimension (it is thin), and it undergoes cooling hardening after stamping, making the fork prone to fracture. It can still be used in a neutral medium. 5) Spring drive. This type of transmission does not require a transmission seat; the transmission spring is tightened onto the shaft sleeve by means of an interference fit, thereby transmitting torque. The ends of the spring are pressed against the step on the shaft sleeve (Figure 34), which prevents axial movement. This method features a simple structure and easy installation, but it requires a specific direction of rotation for the spring; it is important to note that the pump shaft must cause the spring to tighten rather than loosen as it rotates.