overhaul

Overhaul is the process of thorough examination and repair of a machine or system to restore it to its original function or to improve reliability. It typically involves disassembly, inspection of components, replacement of worn parts, machining or reconditioning of critical elements, reassembly, testing, and documentation. The goal is to extend service life, improve performance, or bring equipment back to specification after a defined period of operation.

The term derives from over and haul, with historical use meaning to haul something over again for inspection. In common usage, overhaul can apply to mechanical systems, electrical equipment, or entire facilities.

In mechanical contexts, overhauls are routine parts of maintenance programs for engines, turbines, pumps, ships, aircraft, locomotives, and industrial machinery. A complete overhaul usually requires removing the unit from service, inspecting subsystems, replacing wear parts, machining or reconditioning components to tolerances, and conducting tests to verify performance before returning it to service.

In organizational or policy contexts, an overhaul can refer to extensive reform of processes, governance, or regulations. Examples include tax system overhauls, defense or public administration overhauls, or corporate restructuring aimed at substantial change.

Overhaul is closely related to, but distinct from refurbishment or renovation. Refurbishment typically emphasizes cosmetic or surface improvements, while an overhaul targets restoring or upgrading core functionality and reliability. A planned overhaul is often scheduled to minimize downtime and manage costs.