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What is a Star Pump?

By Charity Delich
Updated: May 17, 2024

A star pump is a pumping device that is primarily used to transport lubricating liquids, such as oil, fuel, or transmission fluid. In general, it works by producing a pumping action, which is created by the movement of rotating gears. As a result of this movement, a constant stream of liquid is discharged from the pump. Star pumps are also referred to as gerotor pumps, a name that comes from the term “generated rotor.”

A star pump is usually made from steel or cast iron, although it can be produced in a variety of materials as well as different sizes and configurations. The pumps can be designed for a range of different purposes. For example, a star heat pump can be used for heating and cooling systems while a star air pump may be used in filtration systems. A star fuel pump or a star oil pump, however, are two of the most common types of star pumps. They are usually used to maintain lubrication in a number of devices or for hot oil filtration.

Most star pumps are comprised of two rotating gears, which are called gerotor gears, that fit together. The inner gear is usually star-shaped while the outer gear is typically shaped like a circle. The star-shaped gear fits inside the circular gear and usually has one less tooth than the circular gear. Generally, the star-shaped gear is the pump driver and the circular gear is the idler. The star-shaped gear moves the circular gear around.

Star pumping generally works by drawing liquid into a cavity and then squeezing it back out. Since the star-shaped gear has one less tooth than the circular gear, a cavity is created when the gears rotate. During the pumping process, the cavity fills with the liquid being pumped. As the rotation cycle carries on, the cavity closes again, and the liquid is pushed back out.

Advantages associated with a star pump include its simplicity, due to the fact that it only has two moving parts. Star pumps are also known for being efficient with a smooth pumping action, making them a good medium for pumping a range of fluids. Additionally, a star pump can operate at high speeds and produce consistent and even discharge of fluids. These pumps usually operate quietly and can function solidly when moving in either direction.

A star pump can be disadvantageous in some cases, and it does not work for all uses. For instance, these pumps typically are not able to pump solid substances. In addition, star pumps often have some pressure limitations.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
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