एक पारंपरिक इंटरनल एक्सपेंडिंग ड्रम ब्रेक सिस्टम में प्रति व्हील असेंबली में स्थापित ब्रेक शूज़ की सामान्य संख्या क्या होती?

Which of the following components is operated to apply and release parking brakes in heavy commercial vehicles equipped with air brakes?

_____ brakes are a type of brake in which the fluid from the master cylinder is forced into a caliper where it presses against a piston. The piston in turn squeezes two brake pads against the disc (rotor), which is attached to the wheel, forcing it to slow down or stop.