Cross & Morse meets nuclear constraints

When power transmission systems manufacturer Cross & Morse was contracted to supply pairs of 5/8 inch BS roller chains to a UK nuclear power station, there were a few problems.

The chains were 100ft long and their lengths had to be within 0.005 inch of each other. Also, access for maintenance was difficult and ordinary lubricants could not be used as they break down when exposed to radiation.

Cross & Morse’s client had previously pre-stressed and matched chains itself, and then applied a special graphite lubricant. Cross & Morse says that its solution was 40% cheaper. It modified its standard 5/8 inch pitch duplex chain and managed to achieve length matching to within 0.001 inch – exceeding the required tolerance by a factor of five.

It also provided a method of lubricating the chains under pressure to ensure reaching the mating surfaces of every link. Finally, a corrosion resistant coating was applied to the chain to counter the extreme operating conditions.