What kind of force acting in the brake system which encounter the lifting material force and to maintain its level.
Cranes work using hydraulics and cables. The cables are wrapped around pulleys and the pulley is turned using hydraulic power. The brake system is simply stopping the pulley from turning by reducing power. The hydraulic system typically will turn a series of gears which in turn spins the pulley that the cable is wrapped around. It's different than a brake system say on a car where when you hit the brakes, pads squeeze on the interior of the wheel rim slowing it down. Cranes you just reduce power and stop the pulley from turning. They also have emergency stops. Older cranes have wedges that would be released onto the cable and then the wedges would grab the cable and slip into a ring. The narrow end of the wedges would slip into the ring first and then as the wedges increased in diameter the grip on the cable would get tighter and then stop the cable from moving. They also have systems on the pulleys to stop the pulley from spinning. They essentially work the same way as a car break. When the emergency brake is triggered, pads will squeeze on the rim of the pulley to stop it. These mechanisms work by friction. They could also have holes around the pulley and a steel pin would be pushed into one of the holes to stop it from spinning. Of course if the force of the weight exceeded the strength of the pin, it would shear.
