Vacuum pumps mechanically generate a consistent vacuum source for vehicle systems originally relying on engine-driven vacuum. Predominantly used in diesel engines lacking a traditional intake manifold vacuum, they supply vacuum for brake boosters, HVAC controls, and emissions systems. These pumps utilize an eccentric rotor and vanes within a housing to create the vacuum, driven by the engine’s accessory belt. Internal designs often incorporate oil lubrication for durability and reduced wear. Output is typically measured in inches of mercury (in. Hg) or kPa, with varying flow rates available to suit different application demands. Modern units may include integrated check valves and mounting brackets for simplified installation.