Photocells
A transmitter and receiver face each other across the opening. If something blocks the beam while the gate closes, the gate stops or reverses.
Loop detectors
A wire loop buried in the ground senses a vehicle’s metal. It keeps a barrier or gate open while a vehicle is in the lane.
Safety edges
A soft strip on the moving edge triggers a stop on contact. It is a second layer of protection if a photocell fails or is missed.
Test regularly
Walk a test object through the beam and press on the edge every month. If the gate does not stop or reverse, switch to manual release and call a technician.