RCD there is always a reason for a design engineer to add a piece of machinery, always. This is why knowing fully how the mechanicals on a lift or escalator should be known by mechanics as it will lead to disasters like a lift rolling away from a floor. Your idea that a worm gear is a 1 way self locking system is totally false. The crown wheel and/or a worm gear of themselves are completely free to spin as they want, so they don't lock by themselves. Even the hoist motor doesn't have a brake by itself which is essentially why there is a brake drum attached. By connecting the motor output shaft to the input connection on the brake drum, and then the worm gear input shaft also to the brake drum connector this gives the worm gear the appearance of strength but it is still on a snap of the shaft away from running away. Im so glad you spoke up about this instead of testing your theory at the job site. Ask questions mate before you do anything!!
