Herringbone gearing

Table of contents

  • What is a herringbone gearing?
  • Where is a herringbone gearing used?
  • Advantages and disadvantages of the herringbone gearing?
 

What is a herringbone gearing?

In the case of herringbone gearing, the teeth are arranged in the shape of an arrow. This is also referred to as double helical gearing. In contrast to straight and helical gearing, arrow gearing is suitable for achieving conveying with as little pulsation as possible. On the one hand, the arrow-shaped arrangement of the teeth improves the intake behavior and, on the other hand, leads to a significant reduction in pulsations. The arrow toothing is preferably used when low pulsation and gentler conveying of the medium is required - than is the case with helical toothing. In addition to the low pulsation, high efficiencies are also achieved with this application.

 

Where is a herringbone gearing used?

The herringbone gearing is often used in extrusion applications and processes where a constant, low-pulsation product flow is required. Product qualities are significantly dependent on conveying, pressure and pulsation fluctuations in the product flow. For best qualities, therefore, a particularly smooth and constant product flow with constant pressure ratios is required.

Operating parameters

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

Pro & Contra

Pro herringbone gearing:

The herringbone gearing has the lowest pulsation. With it, high differential pressures can be achieved and the polymer is conveyed very gently.

  •     Less pulsation Lower
  •     stress on the polymer / shear
  •     Less heating of the product (depending on the process)
  •     Uniform bearing load, as there is no axial thrust
  •     Higher differential pressure due to larger shaft journal
  •     Conversion of existing pumps possible
  •     Integration in gear pumps of other manufacturers possible

Contra herringbone gearing:

  • Elaborate manufacture
  • The gear pair can only be pulled out of the pump or mounted together.
  • Less efficiency compared to other types of gearing

Use of herringbone gearing at WITTE