So I have been researching Mechanical dumbwaiter/elevators and have stumbled upon an interesting part of the system I have only found this on dumbwaiters and not hand elevators. The pulley system somehow holds the load no matter which end is the heaviest. Just see the video
So if anyone knows how this works that would be great, also is there a name for the part that holds the load and if so can you still buy them if you wanted to make a new hand powered dumbwaiter? Also why didn't they just utelise a worm drive?
RCD I have a similar unit. I saved it out of an old warehouse. The unit I have is in like new condition. I can clearly see how the unit holds. It has a inside drum brake. The way the brake sets is what is cool. You need to look in the drum to see. I'll look at it this week and post some photos for all to enjoy.
There is a device that has two moving discs, with a stationary, fixed disc in between them. The outer discs rotate when the dw is moving. The outer discs have long bolts that hold them together, and these bolts are perpendicular to the discs, when the rope is being pulled. The discs are allowed to spin around the fixed disc. But when the pull rope is released, the cab wants to drive the discs, instead of the rope. When this happens, the discs twist in opposite directions. This makes the bolts tilt, and as they tilt, the distance between the moving discs is reduced, because the bolts are tilted. This makes the outer discs come closer together, squeezing the fixed disc, and thusly braking the unit to a stop. Pulling on the rope twists the outer discs in the other direction, straightening out the bolts, allowing the moveable discs to once again move father apart from each other, allowing the cab to move.