Primary impact crushers are a means of crushing medium-hard and non-abrasive stones. Once rocks to be crushed enter into the inlet port, primary crushing operation is carried out by plates on the rotor. Secondary crushing operation is realized when stones coming out from the rotor hit breaker plates. Desired sizes of stones are achieved by adjusting the space between the breaker plates and the rotor through hydraulic components. These machines have hydraulic door opening and a hoist system to facilitate renewal of corroding parts.