Lobe pump

LOBE PUMP

1. Introduction

In this pump, the gear wheels are replaced by propellers of two, three or four lobes.' That's why it is named as a lobe pump. This pump is quieter in operation than other types of gear pumps. This type of pump is used for pumping liquid, gas, and air with low pressures and higher flow rate.

2. Construction and Operation

The principle of a three-lobe pump is illustrated in Fig.4.7. The lobe pump consists of two lobes placed in housing.

The operation of this pump is similar to that of the external gear pump. But unlike the external gear pump, both lobes are driven externally and they do not have actual contact with other. The lobes rotate, creating two chambers between the lobes and the wall of the pump chamber. The lobes are rotated, one being directly driven by the source of power, the other through timing gears.

As the lobes turn, fluid is held between each lobe and the wall of the pump chamber and carried around from suction to discharge. Since the surfaces of the lobes are smooth and curvy, they do not actually contact each other. Thus these pumps do not make noise. Also the volumetric displacement is generally greater than that for other types of gear pumps.

3. Advantages and Disadvantages of Lobe Pumps

The advantages and disadvantages of lobe pumps are the same as for external gear pumps, with the following exceptions :

• Lobe means a part similar to the lower soft pendulous part of the outer ear.

• The output from lobe pumps pulsates more than that from external gear pumps. Since the lobes operate as gears, the greater the number of lobes, the less the pulsation. 

• Lobe pumps tend to wear less than external gear pumps.

4. Ranges

Lobe pumps are available with capacities upto 140 Lps and the discharge pressures upto 30 bar.