Simple Devices, Big Problem Solvers

Articles, Springs Magazine

One day, I was talking to a new customer on the phone. As I started asking him questions on the specifics of the spring he needed, I could tell he was getting a bit frustrated with all the questions. He’d finally had enough and stated, “It’s only a bendy piece of wire.” That, in itself, is a true statement. But that “bendy wire” has a number of dimensions that need to be correct, every time, for the application to perform.

That said, after all my years in the spring business, I still see new designs and approaches for using a spring to close and open something, assist, return and even dig into the soil. And although spring design is limited to the laws of physics, they can still perform so many tasks that make our lives easier.

One of the more prolific users of springs is the agriculture industry, including those that manufacture lawn care products. There are springs in the seat to cushion. You’ll find springs in mower decks that provide tensioning on belts from pulleys. Suspension springs are needed to work in concert with shock absorbers to provide smooth rides and force balancing. Extension or torsion springs are needed to return throttle pedals and levers to a required start position, not to mention that deck flapper that directs the trimmings to far away places.

The engine will have valve springs to open and close critical components, requiring millions and millions of potential cycles with no breakage. There may be extension springs or torsion springs used to operate throttle and carburetion levers. If there are any access doors, hoods or cowlings, they will likely have assist springs to help a human raise them into position to gain access for repair or replacement of worn parts. Torsion springs made from square wire are often used as clutches to grab and secure a rotating shaft, allowing it to spin in one direction and not the other.

Technically, rings are also classified as “springs” since the very definition of the word is that of a device that absorbs energy during its movement and releases it to its original shape. Snap rings are key components in drive train and transmission applications where they are placed into grooves to hold shafts in place, or separate rotating members on the same shaft. Hose clamp rings are used to provide a gripping force to allow everything from air to water to fluid to flow without leakage.

Cantilever springs are usually nothing more than a flat piece of strip steel stamped and/or formed into a myriad of geometries. They are often used to simply provide force and hold something in place.

Torsion bars are another member of the “spring” family. They perform their task by rotating and storing energy, that is released later to raise a hood or trunk. Garter springs are extension springs wrapped in a circular shape and joined at the ends. They provide force over their complete 360 degree circumference and provide constant force on oil seals to be sure no fluid is lost, even after the seal is worn. Garter springs can also be used as belts because they can be stretched between two or more pulleys to allow one motor to spin more than one device with very small power transmission at high speeds.

Belleville washers are shaped to provide force with deflections, similar to the common compression spring. However, they do it with very short free heights and a great force with small deflections. Leaf springs are a lamination of several steel strips tied together to provide special forces for suspension systems.

One of the more unique applications is a small compression spring (with open ends and no grind) wound with the correct pitch for screwing in a small light or bulb. By using a copper material, the voltage could reach the light to make it glow, but the spring allowed the assembly to absorb vibration, therefore greatly increasing the life of the bulb and lessening the possibility of interrupted connection from the power source.

So, as you can see, a “bendy” piece of wire can make short work of big problems. The key is making that same spring the same way, time after time to provide the same service to its application. Which reminds me of another comment from another customer — “Gee… you guys sure are exact.” Yeah…we are. A lot could be “riding” on what we make.



By: Randy DeFord, Engineering Manager Mid-West Spring & Stamping