The Ratchet

Stored energy and the hardest moment to fake

A performer walking across a room and suddenly flying backwards is one of the most familiar images in action cinema — the gunshot hit, the explosion's shove, the creature's strike. The wire descenders and decelerators used for controlled falls regulate energy on the way down; the ratchet does the opposite. It releases energy, sharply and precisely, to drive a body the other way. The physics are straightforward. The engineering required to make that safe and repeatable is not.

A ratchet in the stunt context is an energy-storage-and-release device: typically a pneumatic cylinder or a spring-loaded drum, pre-charged to a specific pressure or tension, and connected by wire to a harness. When triggered, the stored energy discharges, the wire pays out at speed, and the performer accelerates away from the trigger point in a direction and along a vector the rigging team has planned in full before the shot. The visible result — a human being thrown across a set — is a controlled traversal of a predetermined arc. Nothing about the apparent violence is accidental.

What the rig is managing

The core technical problem is the departure pulse: the instant at which stored energy transfers into a body. Hit it wrong — wrong vector, wrong attachment point, wrong rate of acceleration — and the harness either fails to read as impact on camera, or it loads the performer's spine in a way that accumulates injury across takes. The coordinator's calculation begins with what the camera needs to see and works backwards through what the body can tolerate, how the harness distributes that load, and what pressure or spring charge produces that exact result at that exact distance. There is no adjusting it mid-shot.

Harness design matters enormously here. A full-body harness distributes the departure pulse across the torso, shoulders and hips in a way that a belt or single-point attachment cannot. The attachment point on the harness — front, back, side — determines the performer's attitude in the air. A rear attachment pulls them backward and rotates them away from the camera; a front attachment pitches them forward. Both are used routinely; the choice depends entirely on what the scene requires and what the physical environment allows. Rigging the attachment point incorrectly is the kind of error that becomes obvious to a coordinator watching rehearsal and correctable before a live take — which is precisely why low-power rehearsal passes are built into every ratchet setup.

The wire itself runs from the harness, up and over a pulley or a series of pulleys that set the vector, and back to the cylinder or drum. The pulley placement is what converts the raw energy of the discharge into the exact direction of travel on screen. Moving a pulley moves the arc. This is how the coordinator dials in whether the performer goes straight back, back and slightly upward, or back and across — without altering the charge that drives them. The separation of those variables is what makes complex ratchet work plannable rather than merely probabilistic.

One constraint that distinguishes ratchet work from almost every other wire gag: the performer cannot initiate an abort once the device fires. A descender allows constant communication between performer and operator throughout a descent. A ratchet is a single committed event. The abort protocol exists in the setup — the charge, the wire, the attachment, the cleared landing zone — not in the action itself. This is why the count before a ratchet fires is not merely a courtesy but a structural requirement: every person in the chain has to have confirmed their readiness before the energy is in play, because once it is, the gag runs to completion.

Landing is where the preparation concentrates. The performer knows exactly where they will be at the end of the wire's run, and the pad stack or landing surface has been positioned and dressed accordingly, often hidden by the set dressing that makes the landing zone look like a blank section of floor. The performer's body position at landing is rehearsed as carefully as the departure — the instinct to reach out and break a fall with a hand is exactly what needs to be overridden, because a locked-out arm absorbing the landing load is an injury waiting to happen.

The reason ratchet gags read as genuine impact on camera is that they are, in a precise sense, genuine impacts — the acceleration is real, the body's response is real, the landing is real. What is engineered out is the randomness. The violence the audience sees is the remainder after everything unpredictable has been removed by a team that rehearsed the shot until the geometry was right, and then set the charge accordingly.