Spur gearing

Table of contents

  •     What is a spur gear?
  •     Where is a spur gear used?
  •     What are the advantages and disadvantages?
 

What is a spur gearing?

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

We speak of spur gearing when the tooth flanks are arranged parallel to the axis of rotation. The tooth flanks of the spur gearing engage simultaneously over the complete length. The spur gearing is the standard gearing for low to medium viscosity chemical applications. Because the meshing occurs over the entire tooth width, this type of gearing has the greatest efficiency, but also the greatest pulsation. However, pulsation is almost negligible at low viscosities. Torque is usually transmitted from the drive to the gear via a keyway connection. For polymer pumps, other options such as splines are also used.


 

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:

Spur gearing features no 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 and plain bearing design so that shaft breaks are avoided as a consequence. Furthermore, pulsations increase sharply at higher viscosities. A further disadvantage can arise from increased noise development, 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