Garbage disposals are composed of an upper hopper, shredder ring, flywheel, lower hopper and motor. When the garbage disposal is turned on, the flywheel spins at nearly 2,000 rotations per minute. Any garbage that passes through the upper hopper falls directly onto the spinning flywheel, and is pushed into the shredder and broken down.
The flywheel is operated by a motor in the base of the disposal unit and is outfitted with impellers, small rotating devices that operate like propellers to help fling the garbage against the shredder ring that rotates around the flywheel. Once the garbage is ground up, the water from the sink flushes it down into the lower hopper where the waste then exits out through a waste line connector.
There are two basic kinds of garbage disposals: batch feed and continuous feed. Continuous feed is the more common design and grinds up food scraps that are fed into it continuously when it is turned on. Batch feeds are different in that they require the waste to be placed inside the disposal until before it is turned on. Once the garbage is inserted into the unit, a lid is placed on top and rotated to align magnets in the lid and the main body of the batch feed garbage disposal. This starts the unit.