Two Hand Control
A two-hand control is a machine safety device requiring simultaneous use of both hands on separate controls to initiate and maintain hazardous machine operations, such as pressing or cutting. Both controls must be released before another cycle can start, keeping the operator's hands out of the danger zone during hazardous movements.
On a shop floor, two-hand controls are applied as point-of-operation safeguarding for machines like presses, press brakes, shears, and clamping fixtures. Operators place parts, withdraw hands, and depress two separated actuators nearly simultaneously. The machine only initiates hazardous motion when both signals are present within a defined time window (e.g., ≤0.5 s) and stops if either hand is released. Controls are recessed to prevent inadvertent activation. Integration with safety systems includes risk assessments, safe work practices, and functional testing to ensure compliance with WorkSafeBC and ISO 13851 standards.
Does WorkSafeBC require two-hand control on specific machines?
WorkSafeBC does not universally mandate two-hand control for all machines. It requires adequate safeguards based on risk assessment. If two-hand controls are installed, they must function with concurrent use of both hands and require release before another cycle, per OHS Regulation.
What are key safety design requirements per ISO 13851?
Key requirements include simultaneous actuation within a defined time interval, maintaining actuation during hazard, output dependency on both inputs, anti-repeat (release before next cycle), prevention of defeat, and ergonomic positioning to prevent reaching the danger zone.
Why does ISO 13851 note that a two-hand control offers protection only for the person using it?
The device's safety function is based solely on the operator's hand position and actuation. It does not detect other persons entering the danger zone, so additional safeguards like fixed guards or presence sensing are needed for multi-person operations.