Selection of a gear type

What types of gearing are there?

There are basically three different gear tooth systems for gear pumps.

Essentially, there is a choice of spur, helical and herringbone gearing for the pumps. Each of these types of gearing has different characteristics, which are decisive for the use of the type of gearing. The most commonly used type is spur gearing. Classically, involute gearing is used for gear pumps.

Qualitative differences in pulsation behavior

When conveying fluids, it is often important for the process that a constant product flow is present. Gear pumps are used in the plastics industry, for example, to produce profiles or films. To ensure consistently high product quality, the product flow must not pulsate, because otherwise uneven layer thicknesses would result. The graphic qualitatively illustrates the different pulsation behavior of the various types of gearing. If particularly shear-sensitive media are conveyed or if the process requires low pulsation behavior, herrigbone gearing is very suitable.

Compared to oscillating displacement pumps, the pulsation behavior of gear pumps is significantly lower than that of piston diaphragm pumps, for example.

 

The types of gearing and areas of application

Spur gearing

Viscosities:
Low, medium and, as a special variant, also high viscosities
Differential pressure:
120 bar, as special version also up to 250 bar
Volumetric efficiency:
high
Pulsation:
exists

Helical gearing

Viscosities:
Medium to high viscosities
Differential pressure:
250 bar
Volumetric efficiency:
high
Pulsation:
Less pulsation than the spur gearing

Herringbone gearing

Viscosities:
Medium to high viscosities
Differential pressure:
250 bar
Volumetric efficiency:
Lower than with helical gearing
Pulsation:
low