A stainless steel tapered pin with male thread (Figure 1)
A stainless or collar, circular on the outside and tapered inside, with a contact flange.
(Figure 2). This collar constitutes the expandable part of the rail bond.
The expandable collar is not split. It is deformed because of its malleability, expanded without fracture by the penetration of the tapered pin. This ensures the assembly is sealed, eliminating the rist of corrosion due to the ingress of moisture.
Unlike the flange (Figure 3), the rail bond extends slightly beyond the face of the rail in order to eliminate the risk of moisture retention at the rail hole entry. A groove is made in the face beneath the flange in order to encourage the collar to expand as close as possible to this flange, and thereby improve electrical contact with the rail.
The combined tapers of the pin and the expandable collar, together with the diametrical swelling of the collar in the rail hole, provide a large surface area for the electrical contact.
The rail bond permits a drilling diameter tolerance between 0.2 and 0.35mm depending on the type of rail bond. It is possible to install it even on rails containing markings.
Tightening a stainless nut, which has received an anti-seize treatment, makes the electrical connection to the terminal lug.