Fire Truck Cab Entryway Improvements

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Date
2014-12-01
Authors
Werdermann, Rhys
Long, Martin
Cheung, Chee Him
Amin, Youssef
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Abstract
Our team has partnered with Fort Garry Fire Trucks (FGFT) to solve an issue facing their current emergency response vehicle design. Currently in their Crown cab design, the interior floor partially overhangs the entrance steps, creating a tripping hazard while entering the crown. Additionally FGFT’s competitors offer products which have an interior floor that extends the entire width of the vehicle, placing them at a competitive disadvantage when bidding on contracts. FGFT has tasked us with modifying their Crown design to implement a full width floor, integrating automatically actuating steps to create an ergonomic entrance when entering and exiting the Crown. Consulting with our client, they emphasized that they desired a creative concept, one which would differentiate them from the competition. Our final design achieves a full width interior floor, integrating a pair pneumatically actuating sliding steps on either side of the Crown. The actuation is designed to automatically extend the steps when the door is opened past 65°, and to retract the steps when the door is closed past this same point. The steps have been designed to meet the National Fire Protection Association’s standards for automotive fire apparatus. The steps are 18” wide, a design consideration to eliminate any interference between the door and step during the actuation process, while maintaining a functional width for entering and exiting the Crown. A uniform rise height of 8-1/4” has been designed between the steps, with a uniform distance of 8” between leading edges of each step when they are deployed. Steel diamond plate is used to construct the tread face to provide a non-slip surface. Considerations have been made within our design to ensure it fulfills FGFT’s manufacturing capabilities, and to utilize materials common to their Crown design. The frame of each step is constructed of 1-1/2” x 1/8” square 6061 aluminum tubing. 2” x 3/16” square and 2”x3”x3/16” 6061 aluminum tubing is used to construct the subframe used to mount all of our design components into the existing crown frame. Wherever possible, off-the-shelf parts have been used. The pneumatics within our design are powered by an air storage tank that is charged by the fire truck's air brake system. Each step is actuated by its own pneumatic cylinder, an 8" cylinder for the upper step and a 16" cylinder for the lower step, which are connected in parallel so they actuate in unison. Double-acting pneumatic cylinders are used to provide powered out- strokes and in-strokes during actuation. In the fully extended position, the pneumatic actuators remain pressurized to hold the step firmly in place. […]
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