Recreational Child Jumper


Designers:Jennifer Glasgow and Thomas Meese
Client Coordinators:Nancy Curtis, Easter Seals Foundation of NC
Supervising Professor: Dr. Larry N. Bohs
Department of Biomedical Engineering, Duke University, Durham, NC 27708-0281
The goal of this project was to design and construct a recreational jumper for our client, a five year old girl with cerebral palsy. The primary objectives were to make the jumper safe, comfortable, quiet and durable. A commercial swing-quality bungee cord provides for the vertical jumping motion, while a padded seat comfortably supports the child. The device hangs from an eye bolt in the ceiling, and adjustable nylon straps allow the height to be changed. Our client will be able to use the jumper for several years, providing her with a safe and enjoyable form of exercise.
How this project helped
Currently, the client works with her hands and torso at school, but without a jumper, she has no means for safe aerobic activity. She has a walker, but due to her limited vision, the walker does not provide a safe way to exercise without constant supervision. The jumper provides enough support to keep the client upright and balanced, yet provides weight-bearing exercise. Another important benefit is her enjoyment: she loves to jump and spin in the jumper, especially when her parents play her favorite music. Nancy Curtis, the client's physical therapist, feels that "the jumper will provide her only means of safe and independent combination of play and movement."
The jumper is described from the top (ceiling connection) down to the seat. A locking caribiner clips into an eye bolt in the ceiling. Two bungee cords are suspended from the caribiner, with a second caribiner attached to the bottom of the bungees. The jumper uses commercial swing-quality bungee cords (Southpaw Enterprises, model 1938), rather than springs, to offer a greater rate of deflection and quieter operation. Currently, a double bungee loop supports a 60 lb working load. As the client grows, an additional single bungee can be attached in parallel to increase the maximum load to 90lbs. An adjustable nylon strap is suspended from the lower caribiner. The strap has one metal adjuster clip and ranges in length from a minimum of 4 inches to a maximum of 4 feet. A swivel bearing is suspended from this strap, and a caribiner connects it to the center of a a 1.75" diameter metal support bar. The support bar is padded for safety and includes a sewn-on warning label describing the weight limits of the device. An eye bolt is attached to each end of the support bar, and an adjustable nylon strap is suspended from each of the eye bolts. Both ends of the nylon straps are sewn into the seat, which is padded and constructed from parachute fabric.

The seat reaches a height that will allow it to support the child's chest and back. The front two nylon straps are surrounded at the bottom by plastic tubing for cushioning. Three horizontal pieces of 1" nylon webbing are sewn approximately 2.25" apart on the front and back of the seat. The ends of these straps are connected to clips on the left side and adjusters on the right side, allowing for over ten inches of adjustability in the horizontal direction. The upper and lower adjuster straps can accommodate substantial variations in the ceiling's height, and provide an easy means for inserting and removing the client from the swing. The jumper was thoroughly tested by analyzing its components separately. Through load testing and manufacturer specification sheets, we found the jumper to provide a minimum safety factor of 1.9.

Materials for the jumper cost approximately $300.