Metro Vibrating Screens, Allis Chalmers Screen, Twin mechanism, Mining, Dewatering ... 20 x 8 x 3D Allis Chalmers Side Plates: Left Right Side Plates Double : Mechanism. Condition: Excellent. SC3070: 20 x 8 x 2D Allis Chalmers Screen: Single Mechanism. Condition: Good. SC3068: 3000 x 8000 Sala Trommel: Heavy Duty Fitted with Poly Screens