A self-adjusting drum brake

Abstract

The invention relates to the technical field of braking equipment, and discloses a self-adjusting drum brake comprising a braking base plate assembled on an automobile chassis, two brake shoes symmetrically mounted on the base plate, brake pads assembled on the outer sides of the brake shoes, a brake drum assembled on an automobile hub, a parking lever hinged to the corresponding brake shoe, and aparking pull wire connected with the parking lever. Connecting blocks are connected to the inner sides of the two brake shoes. The displacement of a positioning sliding block changes the angle of adjusting arms so that supporting arms expands the brake shoes on the two sides, and thus adjustment of fit clearance is completed. The force strength is high, slipping is avoided, thus the adjustment sensitivity of the fit clearance is improved to enable the fit clearance value to be maintained within the optimal reasonable range, so that the braking performance of an automobile is kept in the bestcondition, the braking performance of the automobile equipped with the self-adjusting drum brake is maintained within the optimal range all the time while driving safety is improved, it is ensured that hub braking force on the two sides is balanced during high-speed emergency braking of the automobile, and accordingly braking safety of the automobile is improved.

Description

technical field [0001] The invention relates to the technical field of brake equipment, in particular to a self-adjusting drum brake. Background technique [0002] see figure 1 After the drum brake is used for a long time, the matching gap between the brake pad and the brake drum will gradually increase due to wear and tear, and the range of motion of the gap toggle lever will become larger. When the range of motion is greater than the ratchet spacing of the gap adjustment nut, the gap will be pushed Turn the adjustment nut to extend the adjustment rod, spread the brake shoe, and maintain the fit gap between the brake pad and the brake drum at a reasonable interval value, so that the brake pad can be tightly attached to the brake drum after a fixed braking stroke, so that the brake The effect is always in good condition. [0003] see figure 2 , the range of activity of the adjustment lever is between the two ratchets, and friction will occur with the adjustment nut every...

AI Technical Summary

Problems solved by technology

[0003] see figure 2 , the range of activity of the adjustment lever is between the two ratchets, and friction will occur with the adjustment nut every time the brake is applied. Since the absolute value of the fitting distance and its variation is very small, the height of the ratchet teeth of the adjustment nut and the thickness of the adjustment lever The ratchet of the adjustment nut and the adjustment lever are easily worn, causing the adjustment lever and the ratchet of the adjustment nut to slip when in contact, the adjustment lever cannot move the adjustment nut, and the matching gap gradually increases, which will make the adjustment rod support The sensitivity of the brake shoe decreases when the brake shoe is opened, and the fit gap between the brake pad and the brake drum is greater than the reasonable interval value, which will cause the braking effect to deteriorate

[0004] see image 3 , the existing clearance compensation action threshold is to adjust the distance between the ratchet teeth of the nut. Between the two clearance compensation mechanism actions, the cooperation distance increases, the virtual travel of the brake pedal increases, and the reaction time for braking ineffective is increased. Sensitivity decreases, and the braking distance when the car is running at high speed will increase, which poses a safety hazard

[0005] Due to the different forces on the wheels on both sides, the matching clearance values ​​of the hub drum brakes on both sides cannot be guaranteed to be consistent, resulting in different action times of the clearance compensation mechanism. The matching clearance value on the side is the minimum value. At this time, there is a difference in the braking force on both sides of the car. When the brakes are suddenly braked, the braking capabilities of the wheels on both sides are different, and the phenomenon of tail flicking, loss of control or even rollover will occur, and there is a big safety hazard.

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