A robustly constructed range of vibratory machines extending from units 0.5 m wide x 2 m long up to units 1.5 m x 4.5 m is available from HMA Materials Handling. The machines are intended primarily for use ahead of primary crushers and are designed to handle large run-of-quarry stone, take the impact of dumped loads and smooth out the flow of material to the crusher. All models have a flat reinforced impact area, followed by a sloping grizzly bar section. The longer machines are fitted with two stepped, grizzly bar sets.

Of rugged construction throughout, HMA Materials Handling Grizzly Feeders are designed to handle run-of-quarry stone up to 1000 mm lump size. The plain section is lined with a 12.5 mm minimum thick replaceable plate in mild steel as standard, with abrasion-resistant manganese steel and rubber elements as options.

All machines in the Grizzly Feeder range from HMA Materials Handling are powered by the Invicta BL Series vibrators to give guaranteed performance for either intermittent or continuously rated duties. All vibrators are dust and weatherproof with protection to IP66. The vibrators operate from a three-phase supply, 50 or 60 Hz up to 650 volts.

Stated throughputs are based on a material density of 1.6 t/m3 and a bed depth equal to the trough height and are therefore very conservative. Higher outputs can be achieved but, if the bed depth is increased, the quantity of fines in the feed should be considered because of the risk of carry-over of fines in the product. Grizzly bar sections have a high capacity rating owing to the long open spacing between the bars. However, they can also pass elongated or slabby material, which may not be acceptable for all applications.