Ideal gear reduction

Reflected inertia

Inputs

Load inertiaJLkg·m²Stated inertia at the driven side of the ideal reduction.

Reduction ratioN:1Driven speed divided by motor speed is 1/N; enter N > 1 for reduction.

Motor inertiaJMkg·m²Rotor inertia for the stated motor condition.

Reflected load inertiaJref

0.0032

kg·m²

Reflected-to-motor inertia ratioN

1.6

—

Motor-side total inertiaJ

0.0052

kg·m²

Jref = JL / N²; Jtotal = JM + Jref

A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.

Calculation snapshot

Formula version 1.0.0

Reflected load inertia	0.0032 kg·m²
Reflected-to-motor inertia ratio	1.6 —
Motor-side total inertia	0.0052 kg·m²

Jref = JL / N² · Jtotal = JM + Jref

Reflected-inertia reference: https://www.motioncontroltips.com/how-do-gearmotors-impact-reflected-mass-inertia-from-the-load/

This printout is a record of displayed inputs and deterministic formula output. It is not an approval, certification, or engineering conclusion.

Method

Reflect a load inertia through one ideal reduction ratio and compare it with a motor inertia.

Jref = JL / N²; Jtotal = JM + Jref

When

Don’t

This reflects one rigid load through one ideal ratio. It excludes gearbox inertia, efficiency, backlash, compliance, duty cycle, peak torque, motor control behavior, and any motor-selection decision.