In 1952, the first treadmills designed for human use appeared, in the form of a cardiac stress test. Not long after, treadmills began to appear in gyms across the country. Modern treadmills feature heart monitors, step counters, fans and safety keys. The safety key generally clips on the walker's clothes and stops the treadmill if the walker slips. Unfortunately, these keys are often misplaced, leaving the owner with an inoperable treadmill.
How a Safety Key Works
There are a few types of treadmill safety keys. Each acts as a type of circuit breaker; without the key in place, the circuit is not complete and there is no power to the motor. Ideally, the key should be attached to the user by a cord, so that if the user should slip, the treadmill stops. This device will also prevent children from operating the machine.
The Magnetic Safety Key
One popular type of safety key is the magnetic safety key. The key is a strong magnet that pulls a metal strip into place, allowing power to travel to the motor. Magnetic keys are the easiest to replace. Simply find a magnet that fits in the place of the key. If the treadmill still does not start, use a stronger magnet.
The Insertion Safety Key
Another widely used safety mechanism is the key that must be inserted into a slot. These keys, usually made of plastic, simply trigger a switch inside the treadmill. If a key of this type is lost, it is easy to replace with a plastic object roughly the same size. As long as it will slide into the slot and trigger the switch, it will work.
Some insertion style keys have raised bumps on the surface. Each bump pushes a switch and, in combination, these switches allow the machine to work. These keys are difficult to reproduce, and usually a replacement must be purchased.
Some safety keys are simply a metal bar that connects two electrodes, which completes the circuit. It is coated in plastic, so the user avoids electric shock. Replacements for these switches must be purchased, as attempting to make a replacement can be dangerous.
Generally, replacement safety keys can be purchased from the manufacturer. Also, universal keys may be available, depending on the type of safety key you own. Always remember that the safety key is there for a reason. Do not try to override the switch, or rewire the treadmill around the switch. Doing so increases the risk of personal injury or fire.