Emergency Stop Button
A mushroom-head button that stops the system with a single action in a hazardous situation, latches when pressed and is released only by a deliberate twist. It must be easy to reach, and pressing it by accident must have an acceptable outcome. AXI HCT400 and HCT402 remote controls have an emergency stop.
An emergency stop does not replace the normal start-stop control; it is a safety layer that sits above it. Two features define it: self-latching (it stays pressed once pushed) and deliberate release (by twisting or pulling). This way the system cannot come back on its own before the hazard has been removed.
- Movement must not start when the latch is released: when you release the button the equipment does not move straight away; you are expected to give the command again.
- Access: it must be where the operator's hand naturally goes, and large enough to be pressed with gloves on.
- Test: at the start of the season and after a long standstill, the latching and releasing behaviour of the button is verified visually.
On wireless remote controls an emergency stop alone is not enough; if communication is lost the receiver must go to a safe state by itself. For this purpose the HCT400 has 250 ms signal-loss protection. The emergency stop covers the operator's will, while signal-loss protection covers the situation that will cannot reach.
Context in which this term is used: Converting a tractor hydraulic lever to electronic control