Why the Gate Changes a Carabiner’s Strength
A carabiner is a metal connector with a hinged opening called a gate. With the gate shut and secured, the frame forms a continuous loop. A load can travel through the carabiner’s spine—the solid side opposite the gate—and around the nose, the hooked end that catches the gate.
If the gate opens, that loop is broken. The load may then bear on the gate or nose instead of being carried through the stronger, continuous frame. Those parts are not designed to take the same force, so the carabiner’s resistance can drop sharply.
What the Lock Actually Does
The gate’s spring helps it swing closed, but spring tension is not a dependable structural lock. A locking mechanism—often a sleeve that turns over the gate—helps keep the gate from opening accidentally. It does not make every loading direction safe: pulling across the carabiner’s short axis, pressing against the gate, or loading it over an edge can still reduce strength or damage it.
Strength markings therefore distinguish between a carabiner loaded along its main axis with the gate closed and other conditions, such as an open gate or cross-loading. The strongest rating applies only when the connector is used in the specified direction and fully secured. A quick check matters because a gate can look closed while its lock remains unscrewed; the frame is not complete until the gate and its locking mechanism are both engaged.
