1. Braking System for a Hospital Bed Approach Calculations Design Team Nicholas Beechnau Aaron Cole Nicholas Nwabueze Matthew Hays Brainstorming sessions were initially held to generate ideas for a new braking system. Designs were sketched on individual time and were submitted to the industrial and faculty advisor for quick feedback. Meetings were held twice a week for two hour sessions to offer and receive advice on designs. Initial ideas were more conventional. Feedback from advisors then led us to develop more unconventional designs. Seventeen designs, which included twenty-one sketches, were presented to the Stryker team. Both innovative actuation designs and braking systems were included in the presentation. After presenting the designs to the Stryker team, one was chosen to be prototyped. The design chosen to be prototyped was selected based on its ability to create instant improvements with only minor modifications to their current bed. The design was optimized then tested and verified as an effective design for increasing braking efficiency. Background Design Constraints * Stryker Corporation, based out of Portage, Michigan has been at the forefront of producing quality medical products and services around the world since being founded in 1941. The goal of this project was to create several innovative braking designs that could be implemented into Stryker’s current Med-Surg products or future products. Current break pedal and actuation must be used. Depressing pedal on one side of the bed must activate entire breaking system. Maximum of 60 lbs. of force to actuate braking system. The height and width of the base must not altered. Actuation of braking system must withstand a 250 lbs. force. Economically, the new design cannot exceed $131 to manufacture. Design must maintain the current “Ball Point Pen” actuation characteristic. The braking system must have a lifetime of at least 15 years. Problem Statement The original design of the Med-Surg bed depressed a metal ring onto each of the tires on the bed. These rings held tires from rotating and swiveling. FLFL R O /2 The final design utilized a lever arm attached to the caster that increased force due to mechanical advantage. FBD of force of ring and lever arm on tire with final design R o /2 The applied force to the tire (F A ) generated by the prototype was calculated by assuming static equilibrium and using equations (1) and (2). Using actual values taken from the prototype for D and d, a theoretical increase of 28.6% in applied force was calculated. D d F R SM pin = 0 Pin  (1) Final Design (2) The brake designed was manufactured and tested at one of Stryker’s labs. Testing was done by loading a bed with weight until brake failure was achieved as it sat on a 10° incline. Due to a non-disclosure agreement exact results cannot be released, but the new design well exceeded Stryker’s requirements for brake holding force. Faculty Advisor Dr. Seugik Baek Industrial Advior Chris Siler *Stryker allowed for many constraints to be ignored to increase number of conceptual designs developed