Breaks crush by gravity impact only. A large cylinder made of perforated screen plates is fitted with internal shelves. As the cylinder rotates, the shelves lift the feed and, in turn, the feed slides off the shelves and drops onto the screen plates below, where it shatters along natural cleavage lines.
The size of the screen plate perforations determines the product size. Sized product falls through these perforations but over-sized pieces will again be lifted and dropped by the shelves until they too pass through the screen plates.
Tramp iron, lumber, or other uncrushable debris that enters the breaker along with the feed will flow to the discharge end of the cylinder. There, these uncrushables are scooped out continuously by a refuse plough which channels the debris out of the cylinder and into a disposal bin.
Often a breaker is used merely to clean debris from coal that has already been sized. This gives some indication of the economy of operation and versatility of this machine.
Breaker cylinders rotate at slow speeds of 10 to 18 rpm depending upon cylinder diameter. Compared with most other crushers are extremely long lived. Screen plates, for example, frequently last 10 years or more crushing millions of tons of coal.
The screen plates in the breakers are designed to be interchangeable, so that the screen plates from the feed and, where wear is greatest, can be switched with screen plates from other areas of the cylinder where there is less wear.
The profile of the perforations in the screen plates has been scientifically designed to obtain a maximum self-cleaning effect, without product bridging across the perforation itself.
The roller mounted Bradford Breaker is suited for coalmines where the feed often includes unusually large pieces of coal. This model will readily accept these larger places of coal without blocking the entry.