As mentioned earlier, the “shear” shredder is also used to size reduce mixed waste. This size reduction device is characterised by its high torque and low rpm. A drawing of a shear shredder is presented in Figure VI-4. As shown in the figure, the unit consists of two horizontal, counterrotating shafts. Each shaft contains cutters to tear and shear the material. In shear shredders, shear and deformation are the primary mechanisms of particle size reduction. The cutters typically operate within a range of 20 to 70 rpm. Because of the shearing action and high torque, shear shredders are commonly used to size reduce items that are difficult to shred, such as tires. They generally perform poorly when fed long, pliable, stringy materials, which tend to wrap around the cutter shafts.