Custom Generative Designed Truck Project

[professor_shartsis]

if they’re for hub motors remember to factor the torque

Hub Motor / Direct Drive Axle Stress Safety Discussion

Hub motor and direct drives place additional stress on axles and trucks compared to gear drives or unpowered skateboards due to the torque the motor applies directly to the axle (a force not present in belt/gear drive systems). There have unfortunately been various instances and reports in the past of wheel separations (wheels falling off the board while riding) with some direct drive systems. Over time some manufacturers have attempted to varying degrees to address the issue by designing custom…

@professor_shartsis

assumptions: roughly 75kv 120a motor current, 8mm diameter axle

axle radius: 4mm

torque per amp: 0.127nm/a = 60/(2 * pi * 75kv)

total torque: 15.24nm = 120a * 0.127nm/a

total force at axle: 3817.5 newtons = 15.27nm / 0.004 meters axle radius

total force at axle (pounds force): 855lbs force = 3817.5n * 0.224 pound force per newton

^ the force applied to the axle from torque from the motor was a factor of 17 times greater than the normal force caused by someone standing on the board.