Adult Modified Rocker Chair Fall 2011

Ben Burgess
Lauren Bush
Austin King
Zach Salada


We are designing a modified chair for a teenage boy who rocks and possibly is autistic. The goal is for the user to be able to safely rock while in class at school.


The teenager is 13 years old with mental disabilities. His rocking has been so severe that he has fallen out of his chair. His parents and caregiver would like for him to be able to move back and forwards while still being able to pull up to a table at school. He is currently learning with an iPad due to limited motor skills with his hands. He is very healthy otherwise but this chair could also have an advantage of helping him with exercise.

Design Specifications

  • The teenager is currently 125 pounds and 5' 1".
  • Required:
    • It must be able to withstand tipping while allowing a moving range to rock.
    • The size and durability should account for withstanding a sitting weight of about 200 pounds and growing to about 6'.
    • Most of the force is from putting his shoulders into the chair with the back motion.
    • The chair must have a seat belt.
    • Must be able to fit under a table at school.
  • Recommended
    • Have an adjustable height.
    • Allow things to attach like a small desk that can hold something the size of an iPad and things for storage.
    • The chair will mostly stay at school, although a lightweight and relatively simple assembly would be a bonus.
    • Have something on the arms of the chair that he grip without being damaged.

Design Concepts

Describe potential/considered designs in this section.


This uses a ball and socket with pins with two springs and a damper. It allows movement forward and backward. The springs will stop the rock of the child, and return him to the upright position. While the damper will absorb the impact of the child against the seat. Seatbelt will be added.


  • Relatively Simple Concept
  • Inexpensive
  • Fairly Safe
  • Not too bulky
  • Lightweight


  • Springs can wear out
  • Will not work under desk

Concept Evaluation

On a scale of 1-5 with 1 being the worst and 5 being the best.

Consideration Design Concept 1 Design Concept 2 Design Concept 3 Design Concept 4
Cost 20% 3 2 4 5
Manufacturability 15% 4 5 2 4
Designability 20% 5 4 3 4
Aesthetics 10% 4 5 2 1
Safety 35% 5 5 1 2
Total Score 21 21 12 16
Design Choice Design Concept 1 or Design Concept 2

Design Overview

After careful evaluation, we have decided to go with a mixture of our design concepts one and two, taking the spring and damper system from concept one and the use of a hinge from concept two. Due to the scarcity of spring constants under 20 lb/in, we have decided to remove the second spring and put the damper on the side of the chair where the child sometimes puts more force into the impact. In this way, we can maximize the effectiveness of our new chair.



Engineering Analyses


Bill of Materials

Part Part Number Use Quantity Dimensions Supplier Price Per Part Total Price
Universal Mobile Base N/A Allows Movement Of The Chair And Immobility When Desired 1 Adjustable, 12" x 12" - 36" x 36" Grizzly Industrial, Inc. $69.95 $69.95
Square Steel Tubing N/A Assembled To Create Our Chair Base 40' 1" x 1", 12 Gauge Stone Steel Located In Cookeville $1.10 Per Foot $44.00
Mounted Bearings 5912K7 Allow Movement Of Chair (Rocking Motion) 2 Shaft Diameter Of 3/4" McMaster-Carr $12.96 $25.92
Boss High Back Executive Chair with Pillow Top Pewter Finished Base Arms N/A Comfortable Chair For The Child 1 27.5" x 32" x 64" $119.94 $119.94
Front Adjustable Spring Damper BJ186F To Absorb The Forces Exerted By The Child 1 12" Length GPM-Racing $56.60 $56.60
Tax: Tax Free
Total: TBD

Part Drawings

Assembly Instructions

Include as many descriptive pictures as possible.

Implemented Design

Include pictures of the final product.

Summary and Conclusions