The Knotts Company
Thomas Articulated Piston

Articulated Piston


Articulating piston pumps work by reduction of a volume using a sealed piston within a cylinder.

  • Oil-less
  • Suitable as compressor
  • High capacity, permanently lubricated and sealed bearings
  • PTFE or carbon piston rings and skirts
  • Long, service-free life
  • Robust design
  • Field service capability
  • High strength stainless steel valves
  • Flow rates up to 5.4 cfm (152.9 l/min), pressure up to 175 psi (12.1 bar)


The articulated piston compressor utilizes the same operating principle as a conventional car engine piston. The articulated piston transfers rotational energy from a motor/pulley into a reciprocating motion used to compress air in a cylinder. The rotational motion is transferred through an eccentric and bearing assembly (big end) to the con-rod, on through the wrist pin (little end) to the piston itself.

As the piston moves down inside the cylinder, air is drawn in through a one-way intake valve. On the upward stroke, this air is exhausted through a one-way exhaust valve. Sealing of the piston to the cylinder is achieved by using two piston rings each backed with a spring to keep them in contact with the cylinder wall. A piston skirt is also used to guide the piston in the cylinder.

The articulated piston compressor is suited to tough, industrial applications that require relatively high flow rates combined with pressure. These compressors are available in AC (single or three phase), pulley driven and the smaller sizes are also available in DC.


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