Different arrangements of pulleys
19, 20, 21 and 22. Are different arrangements of pulleys. The following rule applies to these pulleys:—In a system of pulleys where each pulley is embraced by a cord attached at one end to a fixed point and at the other to the center of the movable pulley, the effect of the whole will be = the number 2, multiplied by itself as many times as there are movable pulleys in the system.
Only the input is driven; every other part of this model moves by physics (MuJoCo), and its ratios are measured. Run it live, change its parameters, or switch the friction off to see the output stop.
- Modelled as
- three cords of links (friction on the sheaves): cord 1, 52 links, from B's hook arm over the fixed sheave A to the weight; cord 2, 38 links, from C's hook arm over B to the weight; cord 3, 28 links, from the hand over C to the weight
- Measured
- load/hand 0.143 (an end of every cord on the weight: 1 + 2 + 4 = 7 parts), B/hand −0.142, C/hand −0.428, sheaves A −1.89, B −3.79, C −7.54 rad/m (strand speeds: −1.905, −3.810, −7.619), pull 8.8 N against (W − 3 W_C − W_B)/7 less the hand's weight 9.1 N, pen ≤ 0.05 mm
- Notes
- Only the hand is driven (a slide in a plumb guide on the hauling part, 6 cm/s). Shared plate 19–22. The plate draws each cord ending at the next block's centre; here each block carries a hook arm out to the strand's plumb line. The plate's loose end hangs off at a slant; the hand hauls it plumb. Negative control: all three cords' contact switched off → the load does not rise (0.000; it drops to its stop while the hand still hauls).
Film (MP4) · GIF · Still (PNG) · Spec (YAML) · Model (MJCF)
