What is one disadvantage of using spur gears in an external gear pump?

The correct answer highlights a notable limitation of spur gears when used in external gear pumps: they are best suited for operations at low to moderate speeds. At high speeds, several issues can arise, including increased wear and tear on the gears, which can lead to premature failure or a decrease in efficiency. The design of spur gears, which relies on direct tooth engagement, does not accommodate high-speed scenarios as effectively as other gear types, such as helical gears.

While other choices may mention valid aspects of gear pumps, they do not encapsulate this specific mechanical limitation of spur gears in high-speed applications. Therefore, the recognition of the limitations on speed is crucial for understanding the operational context of spur gear pumps and their application in hydraulic systems.