A cord lock, also known as a cord fastener, plastic stopper, spring clasp, or cord toggle, is a small mechanical device that attaches to drawstrings or cords and allows them to be tightened and secured without the use of knots. It functions by clamping the cord in place through internal friction, and can be released by applying pressure to disengage the locking mechanism.
Design and Mechanism
A typical spring-loaded cord lock consists of three primary components: a barrel (the outer housing), a toggle or plunger (the inner movable piece), and a spring. When the barrel and toggle are squeezed together, the spring compresses and tension is released, allowing the cord lock to move freely along the cords. When released, the spring expands, the tension is re-engaged, and the cord lock remains fixed in place.
Non-spring variants exist that rely on internal teeth, grooves, or textured surfaces to create friction against the cord, securing it without any mechanical spring element.
Materials
Cord locks are most commonly manufactured from durable, lightweight plastics such as nylon, acetal (POM), ABS, polyethylene, or polypropylene. Some designs incorporate metal springs for enhanced gripping strength. In marine or high-corrosion environments, stainless steel components may be used.
Applications
Cord locks are used in a wide variety of applications, including:
- Apparel: Securing drawstrings on hooded jackets, sweatshirts, sweatpants, and gloves to allow adjustable fit.
- Bags and luggage: Cinching closures on backpacks, duffel bags, laundry bags, stuff sacks, and sleeping bag carriers.
- Outdoor equipment: Tensioning tent guy lines, backpack straps, and mountaineering gear. Their glove-friendly operation is particularly valued in cold-weather conditions.
- Window coverings: Controlling lift cords on window blinds and shades.
- Footwear: Use in no-tie shoelace systems.
Sizes generally range from approximately 1 to 3 inches (25–76 mm) in length depending on the cord diameter and application.
History
Early cord lock designs used metal components, including telescoping cylinders with spring-biased apertures, but suffered from corrosion, sharp edges, and disassembly risks. A significant early patent was U.S. Patent No. 4,328,605 issued in 1982 to Hutchison et al., which introduced mostly plastic components. A pivotal design was U.S. Patent No. 4,622,723, invented by Mark J. Krauss in 1986 and assigned to American Cord & Webbing Co., Inc., which utilized a two-piece molded plastic construction with an integral plunger and W-shaped spring portion.
Modern manufacturing relies primarily on injection molding, with production hubs in Asia and the United States.
