Abstract: A rectangular screen box is supported through a plurality of shock absorbing members from an elongate mounting frame. The screen box has an upstanding wall surround along three sides thereof and within which two vertically-spaced stations are provided. Each station is to carry an elongate screening surface having engaging elements at each longitudinal end thereof to be secured to a respective holding bar member arranged transversely between opposite sides of the surround and near opposite ends of each station. The outer ends of one bar member for each station extend out through an opening in opposite sides of the surround to be engagable by an element to move the bar member for each station relatively apart to longitudinally tension a screening surfaced secured thereto.