Re-inventing the padlockRe-inventing the padlock

Watertown, MA -Under fire from lower-cost, off-brand knock-offs, MasterLock 's market share dipped below 50% five years ago. The company responded with a new plant in Mexico, and recently revitalized the brand with the help of international consultancy Design Continuum.

The net result has been the re-invention of the padlock, and double-digit padlock sales growth, according to John Happener, president and COO of Milwaukee-based MasterLock. "Working very closely with our engineers to leverage our lock-manufacturing competency," Happener explains, "Continuum provided user research and design strategy, graphic design, industrial design, and mechanical engineering."

"We looked at old locks, lock icons, and what people historically visualize when they think of a lock," explains David Chastain, principle engineer at Design Continuum. "Then we synthesized that into our shape models before coming up with the mechanism that corresponded to that image." The end result is a base platform composed of cylinder, case, and shrouded shackle that can be easily customized to meet different needs.

Patented features include internal components and systems for redundant locking and anti-drill plates. But the real driver in the design was ergonomics. "People don't care about padlocks. They care about what the padlock protects," Chastain says. "So we needed a design that felt good in the hand, had some weight to it, and gave consumers a sense of security."

To achieve these goals, Design Continuum changed the familiar box-style lock with U-shaped pop-up shackle to a sleek new oval profile. Instead of just popping open when the cylinder rotates, gearteeth on the cylinder drive the shackle back and forth through the throat of the lock.

"One of the advantages is that you actually need a mechanical means to actuate the shackle in order to open the lock," Chastain explains. "So if you drill out the cylinder, for example, you then loose that means of turning the shackle. The new design feels good in the hand, has some weight to it, and the rounded shape makes it hard to hit directly with a hammer because the lock moves out of the hammer's way, creating a glancing blow, shedding the full impact of a strike."

A screwdriver won't help would-be thieves either, according to Chastain. "If someone puts a screwdriver into the keyhole and gives it a big twist, breaking off the pins inside the cylinder, the die-cast zinc gearteeth are designed to fail before the cylinder does. So there is no way to actuate the shackle, or overpower the lock."

Moving the keyhole from the bottom of the lock to the front enables single-hand access and opening. "We wanted a lock where you could see where you have to put in the key and you could do it with one hand," says Chastain. "So people can open the lock and remove it in one motion and not have to put down your groceries or a suitcase."

Other interesting design features include an integrated rubber sheath around the lock that helps reduce surface scratches. There's a slide cover over the keyhole that keeps dirt or other elements from entering; and the shackle location is near the back of the lock so that it hangs flat on the locker or hasp. "If it's sticking out at an angle and you strike the lock, you are putting a lot of force on the shackle," Chastain says. "So by having it hang vertical we protect the lock as well."