How is an oil pump generally driven?
Most oil pumps in conventional internal-combustion engines are mechanically driven by the crankshaft, usually via a drive gear or short shaft at the front of the engine. Some modern designs—especially hybrids and cars with start-stop systems—use electric oil pumps to provide lubrication independent of engine speed.
Common drive methods in traditional engines
The following overview describes the main methods used to drive an engine oil pump across typical production designs.
- Crankshaft-driven gear pump: The pump is mounted at the front of the engine and is driven by a gear that meshes with the crankshaft’s timing gear or a dedicated drive gear. The pump is typically a gear or gerotor type, delivering oil as the crank turns.
- Camshaft-driven oil pump (in select designs): A subset of engines uses the camshaft to drive the pump via a shaft or gear, transferring rotation from the valve-train to the pump. This setup is less common in modern mass-market engines but appears in some legacy layouts.
In practice, crankshaft-driven pumps dominate contemporary automotive engines, with cam-driven variants largely confined to older designs and specialized applications.
Electric and hybrid lubrication concepts
To improve startup lubrication and efficiency, many newer vehicles rely on an electric oil pump, especially in hybrids or models with advanced start-stop systems.
- Electric oil pump: An electric motor powers the pump, controlled by the engine control unit. This arrangement ensures oil pressure can be maintained or rapidly restored when the engine is not running or at low RPM, reducing wear during starts and idling.
Some manufacturers also employ a hybrid approach, combining an electric pump with a traditional mechanical pump to optimize pressure across operating conditions. In addition, variable-displacement pumps electronically or mechanically adjust flow to match demand, enhancing efficiency.
Why the drive method matters
The choice of drive method affects packaging, reliability, and efficiency. Mechanical, crank-driven pumps are simple and robust, while electric or hybrid pumps offer precise control and better lubrication during startup or idle, at the cost of added complexity and components.
Summary
Across most conventional engines, the oil pump is driven by the crankshaft through gears or a short shaft. Camshaft-driven pumps exist in some designs, but are far less common today. Increasingly, electric oil pumps are used in hybrids and modern start-stop systems to ensure reliable lubrication independent of engine speed, with some engines employing hybrid or variable-displacement configurations to optimize performance and efficiency.
