Basic Gear Principles in the Elevator Industry

Gear Ratio & Basic Formulas

A gear ratio compares the number of teeth on the driven gear to the driver gear. In elevator machines, this explains how a high-speed motor can turn a drive sheave slowly but with high torque.

Key formulas:
Gear ratio = driven teeth ÷ driver teeth
Output speed = input speed ÷ gear ratio
Output torque ≈ input torque × gear ratio

Direction of Rotation in Gear Trains

• Odd number of gears → first and last rotate in the same direction.
• Even number of gears → first and last rotate in opposite directions.
• Idler gear changes direction only, not ratio.

Larger Gear Drives a Smaller Gear

Increases speed, reduces torque.

Smaller Gear Drives a Larger Gear

Decreases speed, increases torque.

Idler Gear

Used to reverse direction without changing gear ratio.

Gear Sequence

Multiple stages reduce speed and increase torque.

Worm Gear Drives

High reduction, compact size, high torque output.

Gearless Traction

Motor directly drives the sheave using VFD speed control.

Efficiency & Lubrication

Proper oiling prevents heat, noise, and premature wear.