Estimating Required Braking Torque for a Mine-Shaft Lift
What factors need to be considered when estimating the required braking torque for a mine-shaft lift operating in a vertical mine-shaft?
Factors to Consider
1. Total Mass: The total mass of the cage, payload, winding drum/brake assembly, and cable must be taken into account when calculating the required braking torque.
2. Acceleration and Deceleration: The different stages of descent, including steady descent at a constant velocity and constant deceleration, require specific calculations to determine the braking torque needed.
3. Cable Properties: The properties of the steel wire cable, such as diameter, cross-sectional area, and linear mass density, play a crucial role in calculating the tension and required braking torque.
4. Winding Drum Characteristics: The effective radius of the cable on the winding drum and the mass and radius of gyration of the winding drum/brake assembly are essential factors to consider in the braking system design.
To estimate the required braking torque for the stages of the descent, we calculate the tension in the cable using the equations T = mg + ma and T = mg - ma. For stage 1, the tension is 7350 N, and for stage 2, the tension is 0 N. The maximum braking torque should be specified based on the largest possible acceleration or deceleration that the system might experience.