HOPPER-FEEDER (EN: transfer hopper, leading hopper; DE: Bunkerfulleinrichtung, Speise-bunker; FR: trémie d'alimentation; ES: tolva de alimentacion; RU: бункер-питатель) is the machine for the steady feeding of the rock masses into the transport means of the continuous action; the link between the excavating-loading equipment of the cyclical action, and the transport installations of the continuous action. They use it within the complexes with the mining-transport equipment and with the receiving devices for the raw materials, which are arriving into the enterprises or into the workshops for the processing (crushing-screening plant, beneficiation plant, and others).

The major units of the hopper-feeder are the receiving (loading) funnel for the placing of the rock masses, which are loaded, and the feeder under the receiving funnel, which is ensuring the issue (unloading) of the rock masses from this funnel. For the separation of the oversized pieces of the rock masses, the receiving funnel is overlain by the grate. Depending on the type and on the physical-mechanical properties of the mass, which is loaded, they use the feeders of the cart, belt, plate, vibration, scraper, roller, screw, disc, drum, and paddle types. Within the open pit hopper-feeders, they mostly use the feeders of the first 5 types.

They distinguish the stationary, semi-stationary, movable, and self-propelled hopper-feeders. The stationary and semi-stationary hopper-feeders, as a rule, are loaded with the usage of the wheeled types of transport, and by the wheeled scrapers. This type of the hopper-feeders is often the constituent part of the stationary or semi-stationary crushing-screening and screening installations.

They use the movable and self-propelled hopper-feeders together with the single-bucket excavators, and with the frontal loaders.

The self-propelled hopper-feeders are equipped with the tracked chassis, and have the rotating unloading conveyor, which is allowing to change the height of the unloading. The minimal voluminous capacity of the stationary and semi-stationary hopper-feeders must be at least 3-4 times, and of the movable and self-propelled hopper-feeders must be at least 2-3 times, relatively to the voluminous capacity of the loading means, namely, of the bucket of excavator (loader), of the bed of the automotive dump truck, and so on.

The stationary hopper-feeders (within the USSR), which are loaded with the help of the railway transport, have the voluminous capacity of 200-300 cubic metres, while the movable and self-propelled hopper-feeders have the voluminous capacity of up to 15-20 cubic metres.