Action classification

　　Single-sided or Dual Actuated

　　 Unilateral actuation and bilateral actuation and braking, not all exist solely in hydraulic or mechanical disc brakes, but mechanical disc brakes are mostly unilateral actuation. Unilateral action means that only one piston will push the brake pads and rub against the disc, while the brake pads on the other side will wait for the opposite brother to push the disc over, so that both sides will have a friction effect. As a result, there have been two theories of floating and fixed calipers. Bilateral action naturally means that there are two opposed pistons in the caliper, allowing the brake pads to clamp the disc from both sides. At present, the number of pistons for disc brake calipers is 1 (one-side actuation), 2 (one pair), 4 (two pairs), up to 6 (three pairs), and the number of pistons is not necessarily equal to the number of brake pads. Because some have two pistons on one side, but it is a long brake block; the two brake blocks may not be clamped bilaterally, because it may be a unilateral actuation type. For example, Magura Gustav M operates unilaterally. How many pistons and brake pads do you have? The mechanical disc brakes that act on both sides are mostly the masterpieces of Taiwanese manufacturers, such as RST, Shen Sha, and Zhong Ying. However, the new face Yingji Company has produced the Winzip M1 with "single-drive, double-side clamping".

TIPS: Simple test: assemble a disc brake or buy a car equipped with a disc brake, stop the car, try pulling the brake lever by hand, staring at the disc and brake pads, and observe the clamping situation, especially the unilateral actuation system. Is the distance of the disc being pushed and folded too obvious, or is it swaying?

Material classification

　　Metallic or Organic Pads Brake pads with different compositions and materials have different friction coefficients.

　　Organic brake pads are made of Kevlar mixed with glass fiber, etc., without any metal powder. It can have a strong braking force, but in high temperature and humidity conditions, the force loss is more severe than that of brake pads containing metal formulations. The advantage is that this kind of brake pad does not conduct heat, and there is no need to worry about the thermal expansion effect of the oil, so it is ideal for use in a closed hydraulic system. The metal brake pads, mostly containing copper or iron powder, are more wear-resistant, and they are less afraid of dust and mud affecting the braking force. However, the heat transfer effect is too good, so it is naturally suitable for open hydraulic systems. Between the disc and the inner and outer brake pads, it is generally emphasized that they must be parallel and equally spaced, and they will be carefully calibrated during assembly to achieve the ideal operating mode of synchronization on both sides and equal force clamping. This aspect emphasizes the principle of bilateral actuation calipers. For some floating caliper unilateral actuating disc brakes, the disc is relatively close to the fixed, non-moving side of the brake pads, even slightly touching, the wheels are not rotating in a static air, there is friction, and it is also said that the speed is imperceptibly reduced.

　　 TIPS: There must be a break-in period between the disc and the brake pads of the new disc brake. With a new disc brake, I want to try its sharpness, which is a bit dangerous.