As shown in Fig. 4a, the circular hole (or semicircular hole) at the lower end of the brake shoe is sleeved (or dressed) on the support pin and is free to rotate around it, that is, only one degree of freedom, The relative position between the drums is determined when the brake shoes are smooth and structurally firm. But the processing of high precision, such as the friction surface processing is not correct, hoof and drum will have local contact in the friction surface wear with the situation will be destroyed. The support for the heavy and medium-sized vehicles.
Floating support, as shown in Figure 4b, the brake shoe at the bottom of the curved surface, reliable in the bearing surface rotation and up and down sliding, both with two degrees of freedom. Due to this feature, the brake shoe has an automatic centering effect and can fall into the best contact position within the brake drum. This is not only the processing accuracy of the lower requirements, and wear can still automatically adjust the heel and drum with the situation. However, due to the uncertainty of the position of the brake shoe, in order to make it does not slip and smooth low reset, must consider the balance of the return spring; also requires adjustment of the brake clearance to avoid friction plate grinding. The support is mostly used for cars and light cars.
With a floating brake, the performance factor is slightly higher than that of a brake with a rotating shoe, and the friction coefficient and the contact area are less sensitive and the brake lining wears more uniform.