What kind of carabiners are used at the pulleys on ziplines?

• A. Supersafe carabiners
• B. 2 screwgates
• C. auto-locking steel to pulley
• D. Steel carabiners with locking gate

Answer: (C)

Connections at the pulley are under dynamic, high-load conditions and must stay closed even as systems move and vibrations occur. Auto-locking carabiners automatically reclose their gates after being clipped, so the gate can’t accidentally swing open during a ride or from movement at the pulley. Using steel provides the strength and wear resistance needed for the pulley interface, ensuring durability over many cycles. Manual locking (like screw-gate types) requires a conscious action to lock, which can be forgotten or come undone under load, and non-auto-locking variants don’t guarantee the gate will stay closed. For these reasons, auto-locking steel carabiners are the appropriate choice at zipline pulleys.