John Hinson wrote:Mike Hodgson wrote:Even cast iron levers are not gorilla-proof - if you apply enough force you can break anything, and whilst most unusual it was not totally unknown for levers to be snapped.
I didn't think signal levers were ever made of cast iron (they were usually wrought) and I have never heard of a signalman breaking one although they would be much easier to break if they had been cast.
The usual cause of breakage is a badly balanced lever repeatedly banging back in the frame over time when "put back". This eventually causes fracture and a lever heading for failure can be detected by being slightly out of line from the remainder.
There have been cases where signalmen have forced the locking and some types of interlocking are more vulnerable than others. Some frames were fitted with brass catch handles specifically designed to break in preference to damage to the locking.
John
Len Coppin broke two at Cricklewood Junction, they were both clamped with a metal strap either side and four bolts as both levers were in the middle of the frame and to have changed them out at Cricklewood would have required the frame to be taken out of use for a day followed by a night of locking testing.