Crane’s Balance

Authors : Hélène Merle(plus d'infos)
Muriel Guedj(plus d'infos)
Jean-Paul Bourbigot(plus d'infos)
Summary :
The pupils are engaged in the technological design of an object: they must draw a construction plan for a crane. When making their prototype, they learn to cut, drill, and assemble the material (wood) with specific tools. This module allows pupils to identify problems related to the concept of balance through the construction of a crane.
Publication : 1 February 2004
Objectives :
Understand the basics of operating levers and scales; build prototypes from the picture of an object or a scale model; observe, analyze and isolate operating systems (movement, balance, pulleys); make construction diagrams; search for technical solutions: assemble fixed or mobile links, usage of pulleys.
Duration :
About ten sequences.
Material :

For the classroom
- toy crane or real observable crane in operation, photos and images of cranes to download

Tools for the pupils 
a handsaw, clamps and a vise, hammer, screwdriver,
a ruler,
a carpenter’s square, a file and sandpaper,
a gimlet
cutting pliers.

Tools for the teacher
a drill and bits timber of 3 to 10 mm in diameter.
Particular difficulty: amount of material necessary for the construction of prototypes.

The materials used (variations are possible)
wooden tile of 20mm,
a wooden board of 200x200mm square and 10mm thick,
spikes and wood screws with a length of 100 mm and a diameter 3 to 3.5 mm (a non-threaded part of at least 20mm should be removed from the head of the screw),
spikes with a length of 30mm and a diameter of 1.5mm,
a reel fishing line in 20/100 (approximately 2 to 2.5 kg of resistance),
red stones or bricks (such as BBQ bricks),
fencing (type of spike in “U” shape),
metal washers (with a diameter of 20mm and a hole  of 3.5 to 4mm),
a hook
wood glue,
electrical wire with a thickness of 4mm,
small curtain rod rings that can be screwed,
a matchbox, plaster (or cement and sand),
various materials on demand (yogurt pots, boxes, string, etc.).

Note :
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This module was proposed by Jean-Paul Bourbigot and put online. The document was then worked on by a team of teachers, as part of an internship with Helen Merle and Muriel Guedj. Sequences have been implemented, and Helen Robin, in a report to  the lINRP, announced the results of this work.
A number of additions and variations were then proposed. Some aspects that were important to Mr. Bourbigot were put into perspective. You will find sometimes in sessions reactions by him, about this second version of the file.
Let’s recall that the proposed activities on the site are proposals, files or reports still open to discussion!