Machine Dynamics Tool
MENG 364 · King Abdulaziz University
Module 6 — Gear Trains
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Module 0 — Mechanism Builder
Module 1 — 4-Bar Linkage
Module 2 — Coupler Point
Module 3 — Force Analysis
Module 4 — Flywheel
Module 5 — Balancing
Module 6 — Gear Trains
Module 7 — Cam Design
Gear Train Type
Simple
Compound
Epicyclic
A simple gear train has one gear per shaft. Each meshing pair reverses rotation direction.
#
Teeth N
Role
+ Add Gear
Input
ω_in
?
rpm
T_in
?
N·m
Efficiency η
?
—
Speed Reducer
Speed Increaser
3-Gear (Idler)
A compound train has two or more gears on the same shaft (keyed together). Allows large ratios in a small package.
Stages (each stage = driver / driven pair on a shaft):
Stage
Driver N
Driven N
+ Add Stage
Input
ω_in
?
rpm
T_in
?
N·m
η/stage
?
—
2-Stage
3-Stage
Back-drive
Epicyclic (planetary) gear train: sun (S), planet (P), ring (R), and arm/carrier (C). Use the tabular method.
N_S — Sun
?
—
N_P — Planet
?
—
N_R — Ring
?
auto
N_R = N_S + 2·N_P (mesh condition). Auto-computed.
Boundary Conditions
Input member
Sun (S)
Arm/Carrier (C)
Ring (R)
Fixed member
Ring (R) — fixed
Arm (C) — fixed
Sun (S) — fixed
ω_input
?
rpm
T_input
?
N·m
Efficiency η
?
—
Reduction
Overdrive
Compound Epi
Gear Train Diagram
Scroll to zoom · Drag to pan · Double-click to reset
e = —
＋ Zoom
－ Zoom
100%
⟳ Reset
Speed & Torque at Each Shaft
Overall Gear Ratio
e = ω_out / ω_in
—
ω_out
— rpm
T_out
— N·m
P_out
— W
P_loss
— W
Direction
—
Per-Shaft Summary
Tabular Method
Three rows: (1) Arm locked, input 1 rev; (2) add x rev to all; (3) set fixed member = 0.
Step
Sun (S)
Planet (P)
Ring (R)
Arm (C)
Results
N_S / N_P / N_R
—
Overall ratio e
—
ω_out
— rpm
T_out
— N·m
Direction
—
Output speed
—