Why does the rail bond get damage or destroy ?
In the matter of fact, the rail gets severe shocking vibration during the train runs over.
The measurement of vibration is to be indicated by vibrating acceleration. The rail sometimes get the vibration exceeding 1 x 10^5 (m/s2) = approx. 10 thousands G. In the condition of private demand level, it will be up to 100G on
JIS basis.
It means very high shocking vibration is to be recognized comparing to the private demand factor.
In this reason, any rail bond or trans touch bond will be proceeding to destroy gradually.
The destroy of rail bond will be accompanied by troubles such as cut off conducting current wire, damage of fixing part of conducting current wire and peel off of bond terminal.
This table and pictures indicate characteristics and destroying conditions of representing examples:
Main destroy symptoms at bond method
| low temperature solder type low pack type bond |
low temperature solder type HP type bond |
welding type copper thermite type |
|
| Symptom | crack of solder, terminal destroy by fall out of current wire | destroy by peel off at connection part | cut off current wire, destroy at connection part of current wire |
| Durability | low | high | high |
 Low pack type bond |
 HP type bond |
 Copper thermite type bond |
|
As above indication at the table and the pictures, any bond gets affection by rail vibration and proceeds to destroy.
In case of HP type bond, the side of current wire will be peeled off initially and this peel off expands to the side of terminal end. Finally it will be destroyed at the condition of 20 percent remain of brazed part.(it means 80 percent peel off)
