In two groups of three and one group of four:
and test a lightweight crane that lifts a variable load (P) from a
structure with a minimum vertical height (V) of 18 inches with a
minimum horizontal (H) clearance distance of 9 inches from the edge of
the tower or footprint of the crane. The crane stucture may
encroach on a 45 degree angle from the lifting point.
crane must lift a load a minimum of 6 inches to qualify. The
crane that lifts the greatest load and meets the portfolio and
interview requirements showing proper application of the concepts
introduced will be deemed th best design.Requirements
- Teams can not get outside help from others
- Teams must submit requests for hardware store material via email or in writing to Ms. P.
team must present a portfolio that presents their design and the
performance tests completed the week before the competition.
- After Competition:
- Reflect as an individual on what you learned about engineering design and yourself by having this experience
as a group on how you could have improved your design and process- What
would you do differently if you had the opportunity to do it all over?
Weights and Counter Weights
- One electric motor -12V DC Motor (Kelvin #850887)
- One motor pulley (#390397)
- One motor mount that must be attached to the crane (#290572)
- Six pulleys (#390592) plus three turning blocks (single pulleys used to change direction of pull, not the amount of force)
(twine) as supplied. String shall be used only for the lifting
cable and for substitution as tension members of the crane. The
amount that may be used isunlimited.
- Balsa Wood 1/8"x1/8"x12'
and 1/8"x 3/8" x 12'. NO OTHER WOOD IS ALLOWED! NO LAMINATIONS OR
ALTERATIONS TO THE WOOD ARE PERMITTED!
- Glue type- No retrictions
- Miscellaneous Items
sheet metal (less than 1/16" thick and 1/4" wide maximum x length
required) may be used for block and tackle assembly and/or for the
pulley axle support to prevent shear on balsa wood only.
- Nuts and bolts or pins/nails as required for pulley assembly axle only.
- Power Supply Available- 12 V DC, 1.5 A
Structural Testing Criteria (Laboratory Experiments and Testing Required)
- Standard US pennies shall be used for weights and counter weights
- Both the weights and counterweights must be suspended from the crane.
container shall be designed to hold pennies for weights and counter
weights, there are no restrictions except that the container may not be
structural or rest on the ground
Suggestion: Organize your team and assign roles to focus on an area (Each person should become a specialist in that area)
- ID tension and compression members
- Determine column buckling (What's the maxium compressive load that a member can withstand?)
- How does changing angles within the structure effect the loading
- Effects of bracing and column buckling
- Using mechanical advantage- pulleys
- Crane stability and rotational overturning
Design, Testing, and Assessment
- Shapes of cantilevers, cranes, and towers that best meet the performance task
- Sketches of Design Solutions- backed up by what you learned in laboratory testing
- Building of Best Prototype Design Solution- backed up by what you learned in laboratory testing
- After competition: Reflection on what could have been improved on and what your team learned by having this experience
- Each work group must maintain a daily progress log of the work done- who did what and what was accomplished
- Each group will be asked to meet deadlines as posted
- While this is a group project, each person must do his/her share of the work.
FYI- Hints/Warnings/ Suggestions
Reference Websites and Programs
- All materials supplied have limits in strength. Exceeding these limits will cause system failure.
- Limits in strength can be increased with proper structure design
- Motors supplied have limits in torque. Exceeding these limits can cause motor failure.
- Employing a proerly designed transmission can increase the torque of the motors.
- Motors can be burned out if overloaded
stability of the structure is an important consideration in the crane
design. Cranes can fall over or crumble if not carefully designed.
- The most important hint that can be given is to take the time to test, test, and re-test your crane.
- YOU WILL NEED TO CONSULT YOUR NOTES, TEXT BOOKS, AND OTHER REFERENCE MATERIALS