greets all. was hoping someone could help me with a problem..
i want to lower a load down a (fixed) vertical steel cable at a constant velocity... i'm looking to build something of a simple mechanical brake. speed isnt too critical.. i'm dont need a specific velocity.. just "slow"... maybe an inch/second? it shouldn't brake however, unless the load drops more than, say, 2 or 3 feet/second.
something similar to what mountain climbers use.. or those safety gadgets for going into high places.. if i'm not mistaken they're made with small wheels that squeeze onto the rope/cable/line and slow a fall.
the load will range anywhere from 100 to 500 lbs.
again, it doesnt need to be complicated (in fact, the simpler the better -- because i'd like to build it myself) ... i like the "squeezing wheels" idea, but i'm not sure how i know enough to crunch any numbers.
i was thinking something like this: a steel bar "X" inches long with a hole at one end, through its short side. the hole just big enough to allow the cable to slide. it would look sort of like a metal flag, perpendicular to the cable. under its own weight (ie, the moment it creates) it wouldnt move down the cable. with a little weight, it would slide down (free fall)... with more weight, however, it should kink the cable, thereby making a straight drop difficult. too heavy and it should make a bend in the cable and stop. the cable is fixed and taught.
again, it is very basic.. but i'm not sure how it would work realistically, how long the "lever arm" should be.. etc.
sorry so longwinded. thanks,
-tony