Herringbone gearing

Table of contents

 

What is a herringbone gearing?

In herringbone gearing, the teeth are arranged in an arrow shape. In this case, herringbone gearing is also called double helical gearing. In contrast to straight and helical gearing, herringbone gearing is suitable for achieving the lowest possible pulsation while pumping. The arrow-shaped arrangement of the teeth improves the feeding behaviour on the one hand and leads to a significant reduction in pulsations on the other. The herringbone gearing is preferably used when a low-pulsation and gentler pumping of the medium is required, which is not guaranteed when using a helical gearing. 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, a particularly smooth and constant product flow with constant pressure ratios is therefore 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 causes the least pulsation. It can achieve high differential pressures and convey the polymer very gently.

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

Contra herringbone gearing:

  • Elaborate production
  • The gear pair can be pulled out of the pump or mounted only together.
  • Poorer efficiency compared to other tooth systems

Use of herringbone gearing at WITTE