Springfree Trampolines...

SUMMARY
Trampolines have been with us for almost 70 years. As their popularity has increased, so have the injury statistics. Until recently the solution to managing impact risks has been to supply add-on padding, rigid-pole barriers and a profusion of warnings. The patented SoftEdge Technology (SET) developed by SpringFree Trampolines had a “Zero Impact Zone” target. It is the result of the first genuine engineering effort designed to remove all sources of impact injury from the domestic trampoline.

INTRODUCTION
In 1908 Henry Ford shipped the first mass produced automobile, the Model T. Compared to today’s automotive technology, it would not be considered “fit for purpose”. Technology has moved on. In 1938, Boeing built the first commercial airliner, the Boeing 314 Clipper flying boat. Compared to today’s aeronautics technology, it would not be considered “fit for purpose”. Technology has moved on.

In 1935, George Nissen invented the first commercial trampoline. Amazingly, compared to today’s mainstream trampoline technology, there has been virtually no change. What is essentially the same design is still being manufactured and is still considered 100% “fit for purpose”. Sadly, trampoline technology, unlike almost every other popular consumer device, has remained frozen in time—until now. A careful analysis of worldwide trampoline injury data initiated in 1994 by Dr Keith Alexander (University of Canterbury, Christchurch, New Zealand) revealed that in order to build a safer trampoline three major impact zones would need to be engineered out of the traditional design:

The springs, which were in the same plane as the jumping surface

- The steel frame, which was also dangerously close to the jumping surface
- The ground or obstructions on the ground, which could be hit as a result of jumpers falling off the trampoline altogether


After 11 years of design, materials innovation, prototyping, and the application of significant international venture capital, SET Technology (SoftEdge Trampoline) is bringing trampoline technology into the 21st century.

TECHNICAL EVALUTAION AND DESIGN REVIEW
The best way to remove hazards is to design them out completely. This is always superior to providing guards, pads or warnings. In order to remove (and not just attenuate) each of the impact zones identified in conventional trampoline design, a whole set of novel engineering strategies needed to be developed and tested. Designs were roughed out, prototyped, tried, patented, and then thoroughly field-tested over a number of years. The final result is an integrated set of sub-assemblies that in concert, remove all the impact zones inherent in the traditional design, and deliver the world’s safest trampoline. A detailed description of the principal design considerations follows:

THE EDGE
There are a number of design issues with the edges of conventional trampolines. Because they are constrained in having a frame and springs around the edge of the jumping surface, the safety goals have been to:

- Protect the jumper from falling through the holes between the springs - Protect the jumper from hitting the steel frame - Prevent the jumper from falling off entirely - Protect the jumper from combinations of the above - Do this at a low cost

Conventional solutions have been to provide padding that is intended to both:

1. Cover the springs to prevent injury from the springs themselves and stop jumpers from falling through the springs;

2. Cover the frame with impact attenuation material to prevent injury from falling on the frame. These solutions have had limited success because:

- Padding material is costly so a minimal thickness of padding is used – frequently less than will meet the standards1. - Unless covered with a fabric the padding is not strong enough to stop falls through the springs (Figure 2). - Unless large enough it does not adequately cover the frame (Figure 3). - Unless thick enough it does not provide adequate protection from the steel frame - Due to cost considerations the industry standard choice of foam loses its impact absorbing properties after more than 3 impacts on the same spot. - Unless well anchored it moves and fails to cover the rails (Figure 4). - It needs to be robustly weather-resistant to function over a reasonable time. - Because the option is open, many customers will not even invest in padding. - To provide protection over time, some form of preventative maintenance must be in place – not common in most backyards.

SOFTEDGE TRAMPOLINE CONCEPTS
Given these built-in limitations to improving the safety of conventional trampolines, an effort was made to re-engineer the trampoline to remove the springs and frame from the jumping surface. Over a number of years more than 10 concepts were investigated, four were built and one chosen for further commercial development.

Ultimately the rod-type trampoline of Figure 7 was believed to provide the best mix of characteristics. After systematic investigations of five rod material options, a pultruded composite was chosen as the most promising for strength, weight and cost. After average results in early consumer tests the material scientists developed a proprietary high performance composite design, tailormade for this application. The final result is a consistent, noncorroding, trouble-free, resilient suspension system.

Safest Trampolines in the World