פטיש בריחה של אוטובוס

Health Hammer / Safety Hammer: Sharp and firm hammer that breaks the glass and escapes in the event of an accident.
2. Cutter: hook-shaped embedded blade, cut off the seat belt in case of accident and escape.
Instructions
Use of safety hammer
In fact, the life-saving hammer mainly uses its conical tip. Because the contact area of the pointed tip is very small, the pressure of the contact point on the glass (not the pressure, but the pressure per unit area) is quite equivalent Large, this is a bit similar to the principle of the pushpin, the film is easily punctured, and the car glass is subjected to a large external force at this point to cause a slight crack, and for tempered glass, a little crack It means that the stress distribution inside the whole glass is destroyed, resulting in numerous spider web-shaped cracks in an instant. At this time, just smashing it with a hammer a few times can remove the glass fragments.
The middle part of tempered glass is the strongest, and the corners and edges are the weakest. The best way is to hit the edges and corners of the glass with a safety hammer, especially the middle of the upper edge of the glass. Once the glass is cracked, you can tap it a few more times. It is said that about 2 kg of pressure can smash the edges of the tempered glass