Complete transmission process
- Power input: When the brake is applied, the brake chamber push rod extends outward, pushing the brake adjustment arm to swing.
- Short axis rotation: Adjust the spline sleeve inside the arm to the spline end of the camshaft short axis, driving the camshaft short axis to rotate together.
- S cam opens the shoe: The other end of the short shaft is an S-shaped cam head, and the cam rotates accordingly. The contours on both sides of the cam push outward to press the rollers on the moving shoe.
- Generate braking force: Two brake shoes open outward around the shoe pin, and the friction plate presses against the rotating inner circle of the brake drum, relying on frictional resistance to slow down/stop the wheels.
- Release the brake: Release the brake and release the pressure in the air chamber; The return spring on the brake shoe pulls the two brake pads together, and the roller pushes the S convex wheel to rotate and reset, restoring the brake clearance and releasing the brake.
Key points of the function of the camshaft itself
-It is just a component that transmits torque and converts force: turning rotational motion into linear thrust that radially expands the brake shoe.
-The short shaft is supported in the bushing of the brake base plate, and the shaft neck rubs against the bushing during rotation;
-The profile of the S cam is an eccentric surface: a small angle can result in a larger amount of shoe opening.