All brake performance and characteristics
发布日期:2015-08-26 17:13:00 Number of clicks:
On heavy duty truck, requires a greater braking force, to adopt completely brake. All brake friction pair of fixed components and rotation components are disc, known as the fixed plate and rotation plate respectively. All brake disc face can contact with the lining at the same time, its structure principle similar to friction clutch.
Compared with the drum brake, disc brake work surface is flat and heat transfer on both sides, the disc rotate easily cooling, not easy to happen bigger deformation, braking performance is relatively stable, brake disc for high temperature expansion after using for a long time makes enhanced braking; And drum brake the single side heat transfer, inside and outside temperature difference is bigger, cause the brake drum is easy to deformation, long after the brake at the same time, the brake drum because of the high temperature expansion, braking efficiency. In addition, the disc brake structure is simple, easy maintenance, easy to realize automatic brake clearance adjustment.
The shortage of the disc brake is the direct effect of lining on the disc, there is no automatic friction force, braking efficiency is low, so if used for hydraulic brake systems required braking control line pressure is higher, the power assist device shall be installed; For parking brake, and add the parking brake actuator is complicated than drum brake, and the application on the rear wheel is restricted.
The working principle of
Brake, the oil is pressed into the inside and outside two wheel cylinder, under the action of the piston in the hydraulic will be two brake block compression brake disc, brake friction torque. At this point, the wheel cylinder of rectangular rubber seal edge on the elastic deformation of piston friction generated under the action of trace. Relax when braking, piston and brake blocks rely on sealing ring of the elastic and elastic recoil spring. As rectangular sealing ring edge deformation is very small, when not brake, friction plate and plate of the clearance between each side will only be about 0.1 mm, it is sufficient to ensure brake lifting. For brake disc is heated expands, its thickness is only the change of the trace, so "delay" phenomenon will not occur. Rectangular rubber seal in addition to the sealing effect, also have the effect of piston return and automatically adjust the clearance. If the clearance between the disc and brake block lining wear, brake seal deformation after reaching limits, when the piston is still can continue to move, until it is compressed by friction disc brake disc. Remove after the brake, rectangular rubber seal will be the same, the distance the piston back with wear before remain standard values. [1]
The advantages and disadvantages
advantages
There is no friction to the potential role and thus brake performance is affected by the coefficient of friction small, performance is stable; After flooding efficiency decrease is less, and only after one or two brake can be returned to normal; Under the same output brake torque, size and quality is smaller; Dinky brake disc along the thickness direction of thermal expansion, not like the thermal expansion of the brake drum brake clearance significantly increase in brake pedal stroke is too large; Is easy to realize automatic gap adjustment, other maintenance repair operations more convenient also.
1, good thermal stability. Because the size of the brake friction liner is not long, its work area is only on the surface of the brake disc area of 12% ~ 6%, so the heat dissipation is better.
2, better water stability. Because the brake pad for disc unit pressure is high, easy to squeeze out the water, after touching water in under the action of centrifugal force at the same time also is easy to get rid of, coupled with the liner for disk wiping effect, therefore, only after the water by the primary and secondary braking can resume normal namely; And drum brake is required to pass through more than ten times braking can resume normal braking efficiency.
3, brake torque has nothing to do with the car was going forward and backward.
4, in the output brake torque under the condition of the same size, the quality of the disc brake and size smaller than drum.
5, the disc friction liner than drum friction lining are more likely to replace after wear, structure is simple, maintenance easy.
6, brake disc and the small gap between the friction liner (0.05 ~ 0.15 mm), which shortens the time of the operation of the oil cylinder piston and brake drive mechanism of force transmission ratio has the potential to increase.
7, the thermal expansion of brake disc will not be like brake drum thermal expansion caused by the brake pedal stroke loss, it also makes the design of the automatic adjustment device can simplify the clearance.
disadvantages
Disc brakes have their own defects. Of manufacturing brake and brake line, for example the demand is higher, loss of friction plate is high, the cost is expensive, and because of the friction plate area is small, relative to the friction of working face is smaller, the need of high brake hydraulic pressure, must want to have power device of the vehicle is to use efficiency is low, so for hydraulic brake systems required braking control line pressure is higher, generally with a servo device.
Braking is rough. Two sticky on the surface of the friction lining friction plate can slide back and forth on the spline shaft, the rotation of the brake is a part. When braking, can make the vehicle to stop in a very short time. Plus pressure plate on the ball groove Angle cannot be infinite, so the brake is not smooth.