Mousetrap car

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Version of a mousetrap car

Mousetrap cars are model vehicles that are powered by the energy stored in a tensioned mousetrap . Competitions are held with them, in which the aim is that such a vehicle can travel as far as possible or as quickly as possible for a short time with the small amount of energy available.

principle

A mousetrap car is little more than a conventional mousetrap ( snap trap ) that moves on at least three wheels . The more is essentially a transmission mechanism ( gear ) between the approximately 180 ° rotation of the mousetrap lever and the rotation of a wheel or an axle of the vehicle.
The stored energy in the mousetrap is identical with that of their leg spring fed by rotation of those windings deformation - work .

Depending on whether the stored energy acts as a driving energy quickly and for a short time, or slowly and over time, a distinction between race cars (speed cars) and wide-driving cars (long distance cars). In the competitions held by schools, the distance that is easier to measure than the speed is assessed. Participants with racing cars are usually at a disadvantage. Their vehicles, which are made fast but lose their drive early on, roll out earlier than the slow but permanently driven long-distance cars arrive.

construction

In order to be able to drive as fast or as far as possible with the small amount of energy, the mousetrap car must be built as light as possible and with low friction . Common, lightweight materials made of plastic (e.g. used CD discs as wheels), wood (e.g. balsa wood for the chassis ) or light metals ( aluminum, etc.) are used.
As a rule, a thread wound on the wheel axle serves as the transmission mechanism, which the mousetrap lever pulls off when it is turned to its starting position. Such a traction mechanism is easy to manufacture: the mousetrap lever can only be extended with a rod. Long-
distance car:
For the longest possible journey, the car should be supplied with a constant drive torque. Since the torque released by the trap becomes smaller while driving, it has to be continuously transmitted to the wheel axle in an ever larger ratio. The lever-pull-thread-wheel axle mechanism tends to do this correctly, but quantitatively imperfectly. At the beginning the transfer ratio grows too slowly and towards the end too quickly. Towards the end, the ratio becomes so large that the lever cuts through when the thread is very stretched. Any remaining energy reserve in the spring shows up as an impact on the lever stop: it is lost for the drive.
The maximum possible route is largely determined when the car is being constructed. The path ratio is chosen to be so small that during the first 90 ° of turning the lever back (the gradient of the torque ratio is the smallest in this area) the driving resistance (friction in the moving parts and rolling resistance of the wheels on the floor) is on a reference floor surely overcomes. The distance translation depends on the lever length, the thread winding diameter on the wheel axle and the diameter of the driven wheels. To ensure that the floor at the location of the competition is rougher and / or more wavy or even better, an adjustment option on one of these sizes (e.g. lever length) is provided.

use

Mousetrap cars are used in schools to teach students skills in designing and making simple objects. So z. For example, the NiedersachsenMetall foundation is holding a state competition in which students can win a prize of 500 euros for their school.

Web links

  • Mausefallenautos , ARD-Mediathek - WDR from February 7th, 2015, 7 min. (Available until December 30th, 2099, Christoph Biemann with the student team from Göttingen for the Formula M race - Mausefallen-Antrieb)

Individual evidence

  1. ↑ Mousetraps race against each other: Race of the mousetrap cars . In: rheinische-verbindungenblaetter.de . ( rheinische-verbindungenblaetter.de [accessed on February 2, 2018]).
  2. ↑ Holiday workshop for children during the Easter holidays - The crazy mousetrap car - Still places available! In: Celler Presse . February 2, 2018 ( celler-presse.de [accessed February 2, 2018]). Holiday workshop for children during the Easter holidays - The crazy mousetrap car - Still places available! ( Memento of the original from February 3, 2018 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / celler-presse.de
  3. ↑ Single -axle vehicles with two wheels are also built and thus also take part in competitions. But they are in the minority, so that two-axle vehicles are generally understood under the term mousetrap car.
  4. ↑ The English term is helical twist spring or shortly torsion spring , leading to confusion with the torsion spring can result. The latter is mainly subject to torsional stress , while a torsion or torsion spring is subject to bending stress .
  5. ↑ Göttinger Tageblatt, Eichsfelder Tageblatt, Göttingen, Eichsfeld, Lower Saxony, Germany: Snap trap as drive - KGS wins races with mousetrap cars. Retrieved February 2, 2018 .