PB-D drum coupling can be associated with the SIME brakes type FNS-VS and SDB drum brakes. PB-D drum couplings are composed of a brake drum (diameters 200 to 710 mm) and a flange hub onto which are mounted pins fitted with rubber bushes.
These rubber bushes are vulcanized onto wear-resisting brass liners which are mounted on the pins with a clearance. This allows them to rotate free and move slightly lengthwise. Then stress exerted onto the bearings is significantly reduced.
The scalloped barrel shape of the bushes guarantees an uniform distribution of loads, even in case of misalignment. This ensures increased durability of both bushes and pins.
The combined elasticity and damping capacity of the rubber bushes reduces both shock loads and critical velocity.
Compressed by an increasing torque, the bushes become stiffer due to the scalloping, thereby reducing the resonance effect at critical velocities.