When the brake is not working, there should be a proper gap between the friction plate and the brake drum, generally 0.25~0.50 mm. The gap is too small to be
Ensure that the brake is completely released, which will cause dragging of the friction pair; if the gap is too large, it will delay the start of the brake and cause the brake to fail, and at the same time
Make the brake pedal stroke too long, causing inconvenience to the driver. During the working process of the brake, the constant wear of the friction plate will cause the brake clearance to gradually
If the situation is severe, even if the brake pedal is fully depressed, sufficient braking torque will not be generated. Therefore, any form of brake is required at the end
The structure must ensure that there is an adjusting device for the brake gap. There are two methods for adjusting the brake gap: manual adjustment and automatic adjustment.
1) Manual adjustment
Generally, there is an inspection hole on the outside of the brake drum web, so that the gap between the friction plate and the brake drum (brake gap) can be checked with a thickness gauge.
Whether it meets the specified value, adjust it if it does not meet the specified value. There are generally several methods for manual adjustment.
(1) Rotate the adjustment cam and the support pin with eccentric journal.
In automobile brakes, if it is found that the brake clearance has increased to the extent that the brake performance is significantly reduced, the adjustment cam can be turned to perform local adjustments.
whole. In this way, the gaps along the circumference of the friction plate can be increased or decreased. When the brake drum is worn to a certain degree, it needs to be reworked and trimmed.
In order to ensure the correct contact state and clearance value between the brake shoe and the brake drum, when the brake is reassembled after repair work, the system should be fully adjusted.
Actuator clearance. In addition to rotating the adjustment cam, the overall adjustment must also rotate the support pin at the lower end of the brake shoe. The journal of the support pin supporting the brake shoe is offset
The end of the support pin extends out of the brake base plate, and a rectangular cross section is milled out so that it can be clamped and rotated with a wrench. Rotate the support pin, everywhere (special
(Not at the lower end of the brake shoe) the gap can be increased or decreased.
(2) Turn the adjusting nut.
The end caps at both ends of the wheel cylinder of some brakes are made of adjusting nuts, as shown in Figure 4-23. Use a flat-blade screwdriver 5 to move the tooth slot 4 of the adjusting nut 1 to make
The rotation of the nut drives the adjustable support 3 of the screw to move axially inward or outward, so that the upper end of the brake shoe can be moved closer to or far
The gap will decrease or increase. After the gap is adjusted, insert the lock piece into the tooth groove of the adjusting nut to fix the angular position of the nut.
(3) Adjust the length of the adjustable ejector rod.
In the self-energizing brake, the lower ends of the two brake shoes are supported on the adjustable ejector rod. The adjustable ejector rod is composed of adjusting nut 1, ejector rod sleeve 2 and ejector rod body 3.
As shown in Figure 4-24. Mandrel sleeve-there is a flange with teeth on the end, the sleeve is made of threads, and the adjusting screw is screwed into the mandrel sleeve by the thread.
The rod body works in coordination. When the toothed flange of the mandrel sleeve is moved, the adjusting screw can be moved in the axial direction, so the total length of the adjustable mandrel can be changed, from
And adjust the brake clearance.
