Supportive Playground Vehicle

Designers: Vanessa Kennedy, Ming Li, Emily Liu, Allen Yu

Client Coordinator: Cathron Donaldson

Supervising Professor: Larry Bohs


Due to congenital myopathy, our three-year-old client has difficulty playing independently and interacting with her peers on the playground.  She cannot hold her head and trunk upright without assistance, and has little strength in her extremities. The goal of this project was to design and develop a safe, supportive vehicle she could use to be more active on the playground. The vehicle has a four-wheeled frame that allows for ease of entry. Pedals drive the rear wheels, while the client handlebar steers the front wheels. The rear handlebar allows an assistant to help the client in propelling forward. The seat and seat pads are tailored to support the client safely and comfortably. With this vehicle, the client can have more fun and interaction on the playground.


The supportive playground vehicle allows the client to be more interactive with her peers on the playground. She exercises her arm and leg muscles while propelling herself forward with new independence. This vehicle provides both a means of therapy and child friendly fun for the client. The client’s therapist commented, “The vehicle is … increasing peer interaction during recess activities and putting her at the same level as her peers.  And of course, there is the overall effect of strengthening her mobility and muscles.” The client exclaimed, “I can’t believe it! Fantastic!”


The Supportive Playground Vehicle (Figure1) uses the frame, wheel, and gear system of the Kettler Kettcar Classic. A highly adapted seat made from the Graco Turbo Booster seat is attached to the frame. The vehicle also has a modified client handlebar, custom made pedals, and a detachable assistant handlebar.

The vehicle frame is appropriated from the Kettcar, a four-wheeled playground vehicle. The frame is made of durable, high-carbon steel and measures 22“ x 21“ x 37“. The gear and chain system is fully enclosed in a protective plastic case, and the wheels feature a long-lasting dual-layer safety tread.

The supportive seat uses a modified Graco Turbo Booster seat. Additions include six removable cushions: two side thigh cushions, two side head supports, a lumbar support, and a cylindrical neck support. All cushions are upholstered in mildew and water-resistant vinyl, and are attached with Velcro for easy removal and adjustment. For added safety, the supportive seat also includes a custom seat belt made from nylon webbing. The seat belt is comprised of a lap belt and two shoulder straps, and is adjustable through plastic D-ring fasteners.

The client handlebar is made from a 2” long x ¾” diameter length of metal conduit, bent into an ergonomic shape for maximum comfort and ease of steering for the client.  The client handlebar is covered in sweat-and-shock-resistant cork tape, making it easy to grip and preventing the user’s hands from slipping off.

The assistant handlebar is made from a 7’ length of ¾” metal conduit, bent in a U shape so an assistant can comfortably push the vehicle. Also covered in cork tape, the assistant handlebar is removable, allowing the client optional independent movement as well minimizing size for storage and transportation. The height of the bar adjusts using a spring-plunger system, accommodating assistants of different heights. The width of the assistant handlebar is 22.5 “, and the possible heights are 46“, 48“, and 50”.

The pedals of the vehicle include an HDPE plastic base and a PVC heel cup, made from a 2” length of 4” diameter pipe cut, shaped and sanded. The pedal base measures 6.5” x 3.5”, and the heel cup measures 2.5” in height. A second base piece connects the custom pedal to the original pedal by compression; two wing nuts allow for adjustment of the fore and aft position. Finally, the pedals feature Velcro-adjustable canvas straps, securing the user’s feet to the plastic base.  The replacement cost for the device is approximately $300, not including the cost of the Kettcar.

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