Sample Problem Statement
Design a lightweight, low cost hand truck that converts simply into a platform truck (see concept sketch below). In platform mode the structure will not have a handle. In either mode, the truck must carry a 300 lb load distributed over either the entire nose plate or the full width of the platform and the length h between the wheel axles. Key specifications:
- Variable height (H) handle ranging from 40 to 50 in.
- Minimum length L will be 28 in.
- Width of truck will be 20 in.
- Nose plate will extend no less than 10 in.
- Design for impact (eg. dropping off a curb): Assume the 300 lb load drops from a height of zero above the truck (see Hibbeler (1997), sec. 14.4, Eq 14.34 in particular).
- As a precaution against material yielding, set the factor of safety (FS) to 1.3.
- Select wheels with rubber tires to prevent marring floors, yet prevent slipping. The upper set of wheels must swivel.
The design objectives are light weight and minimum cost in that order. Hence a figure of merit equal to the weight of the truck in pounds multiplied by the cost in dollars is to be reported. Costs are to be determined using nominal retail prices.
- The center-to-center distance between the two wheel axles is L.
- The handle shown is for illustration only. Your design may differ.
- The nose plate is the bottom plate resting on the floor when the truck is standing upright.
- Adjustment of the handle height should be simple, safe, and easy to do.
- The nose plate should not mar the floor when the truck is resting upright.
This material is based upon work supported by the National Science Foundation under Grant No. 0633602. Any opinions, findings and conclusions or recomendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).
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Pennsylvania State University
Department of Engineering Science and Mechanics
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