Spur gearing

Table of contents

 

What is a spur gearing?

The spur gearing is the standard gearing for WITTE gear pumps and can be used for low to medium viscosities.

We speak of spur gearing if the tooth flanks are arranged parallel to the axis of rotation. The tooth flanks of the spur gearing engage simultaneously over the entire length. Spur gearing is the standard toothing for low to medium viscosity chemical applications. Because the meshing takes place over the entire tooth width, this type of tooth system has the greatest efficiency, but also the greatest pulsation. However, pulsation is almost negligible at low viscosities. The torque transmission from the drive to the gear wheel is usually carried out via a feather key connection. Other options such as splines are also used for polymer pumps.

 

Where is the spur gearing used?

At WITTE, spur gearing is used in the POLY high-pressure pumps and in the CHEM series.

Operating parameters

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
 

Pro & Contra

Pro spur gearing:

The spur gearing is distinguished through the non-existent axial thrust and has the best volumetric efficiency.

  • No axial thrust
  • Good volumetric efficiency

Contra spur gearing:

At higher viscosities, the spreading forces increase when squeezing out the pumped medium. This can be counteracted by a suitable gear wheel and a plain bearing design so that shaft breaks are avoided as a consequence. Furthermore, the pulsations will strongly increase with higher viscosities. Another disadvantage can be increased noise, which can occur at high speeds. The reason for this is the abrupt onset and break-off of power transmission along the entire tooth flank length.

 

Use of spur gearing at WITTE