How do lobe pumps differ from external gear pumps?

Lobe pumps and external gear pumps are both types of rotary positive displacement pumps, but they differ in their design and operational characteristics.1

• Rotor Design: While external gear pumps utilize gears to move fluid, lobe pumps feature rotors equipped with two, three, or four lobes.1
• Drive Mechanism: In a standard external gear pump, one gear is driven while the other runs free. In contrast, both rotors in a lobe pump are driven.1
• Performance and Wear: Lobe pumps are less subject to wear than external gear pumps. However, they produce a more pulsating output compared to the constant, nearly pulsation-free delivery of gear pumps.1
• Application: Because gear pumps rely on the pumped liquid to lubricate internal moving parts and are subject to clogging, they are generally unsuitable for liquids containing solid particles. Lobe-type designs are also notable for their ability to function as compressors for pumping gases.1