What is the reason why the car handbrake is loose or can't be opened?

The reasons and solutions for whether the handbrake is loose are as follows: the handbrake line does not return: just replace the handbrake line. The professional name of hand brake is auxiliary brake, which is different from the principle of brake. Connect the steel wire to the rear brake shoe to brake the car. Long-term use of hand brake will cause plastic deformation of steel wire, which is irreversible, so long-term use will reduce the utility and increase the stroke of hand brake. The handbrake also has a return spring. When the hand brake is pulled, the spring will be stretched, and when the hand brake is released, the spring will return to its original length. When the handbrake is used for a long time, the spring will deform accordingly. Too low temperature: when the weather is too cold and the temperature is too low, the skin of the drawstring of the handbrake will harden or freeze if there is water, so even if the handbrake is put down, the drawstring inside will not return to its original position, and will be exposed to the sun or drenched with boiling water. In addition, the brake pad and the brake drum are frozen, which leads to the combination and separation of the two parts, which need to be separated by boiling water shower or flapping.