Belt reduction to rack and pinion
Calculator 1
Where the load goes — and where it fails
NEO at a 60 A current limit, slide jammed. Imperial first, metric in parentheses.
Losses ignored; steady stall at the current limit. A sudden jam spikes higher — see the shock factor in the calculator.
What the mechanism looks like
NEO turns a 15T pulley, a 9 mm belt drives a 32T pulley on a ½ in hex shaft, and two 32T pinions on that shaft drive the racks.
Side views: pulley, pinion and hex drawn to scale from pitch diameters. Top view: layout only.
32T bore force goes from 0 to 56 lbf as current rises
Failure line appears once the allowable is verified.
Allowables pending. No verified allowable applies yet, so this is not a pass or a fail.
Show all numbers
How this works
The scrimmage failure: a NEO with a 15T pulley, 9 mm belt to a 32T printed pulley on 1/2 in hex, driving two 32T pinions on a rack. At a 60 A limit the 32T pulley sees about 3.1 N·m, and its printed hex bore still rounded out.
Belt tension is the same at both pulleys; torque is not. That is why the bigger pulley is where the bore fails.
Torque multiplies through a reduction, and the joint with the smallest contact area fails first, not the most obvious part.
Students predict which joint fails first, run the numbers, then turn a printed hex pulley on a torque wrench until it rounds out.
Estimates for learning. Losses are ignored. Verify the numbers before relying on them.