Spare tire is an important part of the car, and the necessary jack of the replacement wheel is an important accessory of the spare tire. On the 15 day, the reporter learned in the interview that many drivers do not know how to use jack at all. It is not known that the use of jacks in the wrong places will cause great damage to the vehicle. "Jack can be generally divided into rack jack, screw jack, hydraulic jack and inflatable Jack four kinds. The rack jack is more commonly used in household jacks, because it has the advantages of light weight, small size and easy storage. But because the weight of the support is limited, it is usually equipped with a family car with a weight of about 1 tons. Senior automobile engineer Mr. Jiang said that manufacturers will normally provide suitable Jack according to the self weight of the vehicle. The general car is equipped with a jack bearing less than 1.5 tons, while the cross-country vehicle can be weighed about 2.5 tons because of its heavy weight. Therefore, large cars should not be used to jack up small cars, so as to avoid potential safety hazards when repairing vehicles. It is known that at present, a kind of inflatable jack is popular among self driving enthusiasts. It uses the tail gas of the vehicle to inflate the gas package, and the maximum weight of the jack is about 4 tons. It is suitable for the rescue of the difficult and dangerous conditions or the self rescue and relief of the off-road vehicles. "If the vehicle is not completely fixed before the vehicle is supported, it is likely that the sliding of the vehicle is likely to be caused by the sliding of the vehicle. Once the car slips from the jack, the damage to the tool is secondary. If the injured person is injured, it is too bad. Mr. Jiang said. According to the introduction, it is necessary to use the jack to stop the car, pull up the hand brake, and put the manual block into the 1 or the reverse gear, and the automatic block should be put into the P gear. Then the jack must be used on a hard and flat pavement. If it is a soft ground, such as mud or sand, it is recommended to use a jack or a stone plate to operate under Jack before using the jack so as to reduce the pressure to prevent the jack from falling into the soft ground. Many owners have never used or changed their spare tires in person, and have not carefully read the introduction of the jacks and the support points in the vehicle instructions. According to the introduction, the bottom of the body has a special support point supporting the jack, the support point of the home car is often in the side of the side side of the side, like the two sides of the chassis, about 20 centimeters in the back of the front wheel, and about 20 centimeters in front of the rear wheel. The fin is out of the chassis plate and can withstand a larger pressure. If the jack is supported on the plate of the plate, it is likely to cause unnecessary damage to the chassis. In addition, it is not proper to support the hanging hem arm. If the jack slips down, the chassis and Jack will be damaged. The jack arm of many household cars is divided into body structure. It needs to be rotated with the supporting wrench and sleeve, so in the lifting jack, the force should be uniform, too fast or too hard.