Instrumented tunnel scroll wheel

  • electronics encapsulated in the customer scroll wheel
  • solution without connection and unvisible scroll wheel mounted
  • autonomous and wireless equipment
Encapsulated electronics

Starting point

A tunnel boring machine manufacturer wishes to instrument its scroll wheels to plan their replacements


The environment of the wheel is very constrained: high vibration, temperature at 100 ° C, strong shocks by falling stones


Electronics encapsulated in the wheel: no connection for ease of use

Customer issues

A TBM manufacturer asked us for a wear measurement solution on a scroll wheel head.

  • The scroll wheel must be able to be dismounted by anyone (no knowledge of electronics required but rather a person accustomed to construction sites).
  • Harsh environment: continuous falling of gravel and pebbles on the thumb wheel, hot water pressurized with detergents, operating temperature up to 100 ° C.
  • Because of the pressure on the rock to shred it, the vibration of the part is important and continuous.

EFS answers

These constraints are integrated into our solution and allow a response perfectly adapted to the requirement:

  • Electronics embedded in the scroll wheel (resinated and placed under the metal parts)
  • 3 solutions developed to avoid any electrical connection:
    – Data transmission by radio, including in case of partial immersion
    – Battery life adapted to the mechanical life of the wheel.
    – Contactless identification of the wheel for monitoring on the cutting head.


  • The solution deployed was radio transmission because it simplified the wiring in the scroll wheel and in the TBM.
  • This integration made it possible to know more precisely the environment in which these knobs are used and to intervene on them only when necessary. The ROI is quickly validated due to the cost of immobilizing the TBM.
  • The entire solution is returned to the driver via a CAN field network available on the TBM.
Encapsulated electronics