The lifting speed of a Electric Screw Jack is primarily controlled through the drive system. Key methods include variable frequency drive (VFD) and mechanical speed control.
VFD is the current mainstream solution. It uses a frequency converter to adjust the motor's input power frequency, thereby adjusting the motor speed. For example, if the motor's rated speed is 1450 rpm at 50 Hz, reducing the frequency to 25 Hz can reduce the speed to 725 rpm, directly reducing the screw's rotational speed and enabling stepless adjustment of the lifting speed. This method offers advantages such as a wide speed adjustment range (typically up to 1:10), high speed stability (error ≤ 1%), and high torque at low speeds. Electric Screw Jacks are suitable for heavy loads or applications requiring precise positioning (such as stage equipment lifting).
Mechanical speed control uses a gearbox or pulley to change the transmission ratio. For example, a two-stage gearbox installed between the motor and screw, with a high-speed gear ratio of 1:1 and a low-speed gear ratio of 1:5, can reduce the lifting speed to 1/5 of the original speed. This method has a simple structure and low cost, but the speed range is fixed (usually 2-3 gears), and the motor is noisy at high speeds. It is mostly used in situations where speed accuracy is not critical (such as cargo lifting).
In actual applications, the choice should be based on a comprehensive consideration of load, speed accuracy, and cost. Variable frequency control is preferred for heavy loads and high-frequency speed regulation.
