Science Projects Index

The Car Seat Belts

Car seat belts are a must for our safety. One can make a car seat belt at home.

Things Required : A cotton reel, small screws of about 2.5 inches, nuts, 3 inch bolts, 4 mm thick ruler, adhesive tape, elastic band, string, vise, drill and 5 mm bit, screw driver, scissors, wooden bar 6 inches x 18 inches.

Activity : Holding the cotton reel in a vise, drill a hole in it. The hole should be perpendicular to the central shaft and should be big enough for the bolt to pass through. The bolt is then passed through it. Some space is left at the outer end for the 5 nuts. The remaining bolt shaft is covered with tape. The five nuts are put into the bolts at the other end. Allow it to move freely.

Next, screw the cotton reel to one end of the wooden base. On its opposite end tighten about one cm of another screw. A third screw is tightened at about two inches from the first. It should form a right angle. The elastic band of four inch length is fixed to the second screw. A string of about 18 inches long is tied to the other end of the elastic. This acts like a real seat belt. The bolt should extend equally on each side of the cotton reel. When wound around and pulled, the reel shall rotate. When the grip on the string is loosened, the elastic will pull the string back. If it is pulled quickly and suddenly it will lock tight just like a car seat belt.