The function of the speed change device for hollow glass equipment is to change the output speed and torque of the power machine to meet the needs of the actuator. If the actuator does not require speed change, a fixed transmission system or a standard reducer can be used. Many machines or equipment require the actuator to be able to change speed. For example, a coal cutter should be able to change the traction speed under different working conditions and different coal seam thicknesses; a bulldozer should be able to change the driving speed under different working conditions; general machine tools require the main motion and feed motion to be able to change speed over a wide range to meet the requirements of processing versatility (different diameters, materials, processes, precision, surface quality).

The basic requirements for the speed change device of hollow glass equipment are: it can transmit sufficient power and speed; high transmission efficiency; meet the requirements for speed change range and number of speed changes; small size, light weight; noise within acceptable limits; simple structure, good manufacturability, measurement, assembly, and maintenance; good lubrication and sealing, able to prevent the "three leaks" (oil leak, air leak, water leak).

The size of the transmission components of hollow glass equipment is determined by the transmitted torque. When the transmitted power is constant, the higher the speed of the transmission components, the smaller the transmitted torque, allowing for smaller structural dimensions of the transmission mechanism. Commonly used speed change devices include the following types:

1. The slip gear speed change mechanism for hollow glass equipment, which has a double or triple slip gear mounted on a certain shaft in the transmission system (integrated or combined structure). By changing the engagement position of the slip gear, different speed levels can be obtained. The characteristics of the slip gear speed change mechanism are: it can transmit larger torque and speed; speed change is relatively convenient and reliable. However, the slip gear cannot change speed while running, and to facilitate engagement, straight-toothed gears are often used, resulting in less smooth transmission and higher noise.

2. The clutch speed change mechanism for hollow glass equipment, which includes tooth-insert type, gear type, and friction plate type clutches. The tooth-insert type and gear type clutches belong to rigid transmission, with accurate transmission ratios and the ability to transmit larger torque, but they cannot change speed while running.

3. The exchange gear speed change mechanism for hollow glass equipment, where the gears in high-precision screw-cutting lathes are the speed change mechanism of exchange gears. The characteristics of the speed change exchange gear mechanism are: simple structure, no need for speed change control mechanism; fewer gears are used to achieve the same number of speed changes compared to slip gear speed changes. However, changing gears is time-consuming and labor-intensive, and the exchange gears have a cantilever structure, with poor rigidity and lubrication conditions. Therefore, it is suitable for equipment that does not require frequent speed changes.