Can a double-start worm gear drive in either direction?
Double-start worm gear direction
Yes. Reversing the worm reverses the wheel's rotation, so a double-start worm gear can transmit motion in either commanded direction. That does not mean it will safely hold or resist reverse driving in every application. Lead angle, friction, lubrication, temperature, wear, load and the supporting assembly determine the practical behavior.
What a double start changes
A double-start worm advances the wheel farther per worm revolution than a single-start design. It commonly trades some reduction and backdriving resistance for faster wheel motion and potentially better efficiency. Confirm the required ratio, duty cycle, lubrication and thermal margin before selecting it.
Example: a positioning axis
For an actuator that must move both ways, specify the input direction, output torque, holding requirement, start-stop frequency and lubricant. PairGears can review those conditions with the drawing rather than assuming self-locking from the worm start count alone.
Related question: How can I reduce gear whine?
