Heavy equipment are machines. They are specially designed for completing construction tasks, which include digging. Other known names for heavy equipment are "heavy machines", "heavy hydraulics", "construction equipment", "construction machines", "construction hydraulics", "engineering equipment", "engineering machines" and "engineering hydraulics". They are typically operated by skilled workers that have gone through specialized training. While many categories of equipment utilizes continuous tracks for rough conditions, others favor tires when possible for their greater mobility. The tires selected play a significant role on the production of the project and the cost of the heavy equipment. These three types of tires include, transport for earthmoving machines, work for slow moving earthmoving machines, and load and carry for transporting as well as digging. Heavy equipment applies leverage, like other simple machines (levers, pulleys, etc.), to multiply the effectiveness of the energy put in. The majority of these machines use diesel power to complete tasks.