Abstract: An impact roll crusher for grinding up material, for example in mineral mining, employs a roll equipped with impact heads which co-operates with part of a conveyor transporting the material. The roll is rotatably mounted in a housing and a hood is connected to the housing to deflect and discharge the crushed material. The crusher roll is driven by a belt coupled to pulleys on the roll and on a drive motor shaft. The drive motor is supported by a bracket pivotably mounted on an inclined baffle wall of the hood. The roll drive adopts a position below the upper surface of the crusher housing. A tensioning device operable to adjust the tension in the drive belt is coupled to the bracket and adjusts the pivotable movement of the bracket.