Glossary · Guards and machine motion
Reciprocating motion
In machine safety, reciprocating motion is back-and-forth linear motion that can create crushing, shearing or impact hazards, for example at the ram of a press or the table of a planer.
- Machine safety
- Risk assessment
In one sentence
Reciprocating motion of rams, pistons and tables repeats a crushing or shearing cycle; the hazard sits where the moving part meets a fixed one.
Example
The pusher of a carton erector moves back and forth once per cycle and can crush a hand against the magazine frame at the end of its stroke.
How it applies
- Risk assessment: Assess both ends of the stroke and any gap the moving part closes during travel. The typical harms are a crushing hazard at the end position and a shearing hazard along the moving edges.
- Machine safety: Many presses and forming machines combine reciprocating motion with the point of operation, where material must be fed by hand. Guards, two-hand controls or light curtains are then chosen according to the feeding method.
- Maintenance: Pneumatic and hydraulic cylinders can move when pressure is released or restored. Maintenance instructions should cover venting, blocking and securing the ram.
Reciprocating motion vs. oscillating motion
Reciprocating motion is straight-line back-and-forth travel. Oscillating motion is back-and-forth swinging around a pivot.