RAIL BONDS

DESCRIPTION


Rail bond is the connection element, allowing mechanical and electrical link between the lug of the cable and the rail.
Reliability of the connection is very important. A connection defect between a cable and the rail applies directly on the installation distribution and consequently on the traffic regularity.
The rail bond enables to insure the current conduction of signalling current and return of traction current circuits.


PRINCIPLE OF THE DUBUIS "RAIL BOND"


DUBUIS "rail bond" consists of 2 assembled parts :
  • A stainless steel conical dowel having a male thread (illustration 1).
  • A tin-plated copper bush being cylindrical on the outside and conical on the inside with a contact flange (illustration 2).
Drilling in the web of the rail has to be carried out before setting of the rail bond.

The rail bond is set with a hand hydraulic tool. By means of a release valve, adjusted in factory, which limits the hydraulic pressure force, this tool calibrates the force used for setting the rail bond into the rail.

The expansible bush is not split. Because it is malleable, penetration of the conical dowel deforms it by expansion, without causing a fracture. This ensures that the assembly remains sealed, avoiding the risk of corrosion due to moisture infiltration.

The electrical connection to the terminal lug is made by tightening a stainless steel nut.


ADVANTAGES OF THE DUBUIS SYSTEM :

  • Setting is possible with partial or no visibility whatever the thickness of the rail web.
  • The DUBUIS rail bond can be set up whatever the climatic conditions ; it can be set in the rain and at very low temperatures.
  • The threaded dowel of the rail bond and the nut are entirely in stainless steel, with an antiseizure treatment onto the nut. It remains possible to remove the connection over time.
  • Setting the rail bond does not require any special personnel training.
  • The rail bond maintains stressed contact to the rail ensuring long term electrical contact with no corrosion between contact surfaces.
  • The structure of the DUBUIS rail bond makes it impossible to transpose or omit parts.
  • The reliability of the connection improves the regularity of traffic schedules considerably. This improvement results in a very rapid return of investment.

A WIDE RANGE OF BONDS FOR MANY APPLICATIONS

The rail bond used by the SNCF is the M10 13,5 mm diameter rail bond, symbolized 7.952.0882.

The size of the rail bond is determined to suit the intensity of the current conducted. The greater the intensity of the current conducted is, the larger drilling diameter has to be.

Application
Drilling diameter
Diameter of
threaded dowel
Signalling
Signalling
Signalling and return of traction current
Signalling and return of traction current
Signalling and return of traction current
Signalling and return of traction current
8,5 mm
11,5 mm
13,5 mm
19 mm
22 mm
26 mm
M6
M8
M10
M12
M12 - M16
M16