Someone trapped in a machine is a situation where the instinctive response — reverse the machine and free them — is frequently the one that causes the greater injury.

Stop, do not reverse

The first action is to stop all motion, by emergency stop or by isolation. Reversing a machine to release a trapped limb takes the limb back through the mechanism that trapped it, often causing worse damage than the original entrapment, and it can lose the compression that is currently limiting blood loss. Reversing is sometimes the right answer, and it is a decision for the emergency services with the casualty assessed — not a first response.

Isolate and secure before anyone approaches

An emergency stop halts the machine without removing its stored energy, so a raised part can still fall, a spring can still release, and a charged accumulator can still drive movement. Before anyone puts their hands near the mechanism to assist, the machine is isolated, locked and its stored energy released or restrained. That is what prevents a second person being trapped by the same machine while helping the first.

Compression may be holding the injury together

Where a limb is crushed or trapped, the mechanism itself can be limiting bleeding, and releasing it suddenly can produce rapid blood loss and other serious effects. This is the strongest argument against a well-meant quick release. Keeping the casualty warm, still and talking while waiting for people who can manage what happens on release is more useful than getting them out fast.

Tell the responders what they are coming to

The call needs to say that a person is trapped in machinery, what part of the body, what the machine is, and whether it is isolated. That determines what equipment and which teams are dispatched, and it is often the difference between an appropriate response arriving first time and a delay while more capability is called for. Someone should meet them and take them to the machine rather than describing the route.

Afterwards, leave the machine alone

Once the casualty is clear, the machine stays isolated and untouched. It is the evidence for what actually happened, which is what makes a genuine fix possible rather than a guess about behaviour. Freeing a jam, refitting a guard, or resetting a control before anyone has examined the machine destroys the only record of the state it was in.

For why stopping is not isolating, see what emergency stop does not do and stored energy.

Related standards

The standards below set the design requirements, classification and test methods behind the safeguards and equipment referenced in this note.

• EN ISO 13850 — Emergency Stop Function
• ISO 12100 — Safety of Machinery: General Principles

Frequently asked questions