Machine Design

Keeping wires and cables connected

Electrical plugs, connectors, and receptacles often use terminal screws to connect incoming and outgoing wires and cables.

Heat and vibration can loosen these screws and break the electrical connection. To prevent this, engineers at Marinco Industrial Group, Napa, Calif. (, developed Perma-Lock terminals. In this design, the terminal screw tightens down on a contact tang, so the screws exert an upward force on a collar overleaf. This lifting action locks screw threads in place and relieves stress on the terminal. As a result, thermal cycling and vibrations cannot loosen the screws.

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