Mechanical engineering is one of the broadest engineering disciplines.
Mechanical engineers research, design, develop, build, and test mechanical and thermal devices, including tools, engines, and machines.

Duties
Mechanical engineers typically do the following:

Analyze problems to see how mechanical and thermal devices might help solve the problem
Design or redesign mechanical and thermal devices using analysis and computer-aided design
Develop and test prototypes of devices they design
Analyze the test results and change the design as needed
Oversee the manufacturing process for the device
Mechanical engineers design and oversee the manufacturing of many products ranging from medical devices to new batteries.

Mechanical engineers design power-producing machines such as electric generators, internal combustion engines, and steam and gas
turbines as well as power-using machines, such as refrigeration and air-conditioning systems.

Mechanical engineers design other machines inside buildings, such as elevators and escalators.
They also design material-handling systems, such as conveyor systems and automated transfer stations.

Like other engineers, mechanical engineers use computers extensively. Computers help mechanical engineers create and analyze designs,
run simulations and test how a machine is likely to work, and generate specifications for parts.