baulks with enormous force which killed 18 and seriously injured 11 people. Investigation All electrical and mechanical components of the winding system were thoroughly investigated to find the cause of accident. Electrical systems were found to be working as supply of compressed air was available above the servo cylinder. However the brake shoes were about clear of the brake paths as the vertical brake rod had broken into two pieces. So the investigation concentrated on the failure of the brake rod. A chemical analysis proved that the material of the brake rod (carbon steel with the designation En8, conforming to British Standard 970:1947) was within the specification demanded at the time of manufacture. Metallurgical examination of the brake rod showed that it failed because of fatigue. There were many secondary cracks around the fracture surface which were detected by magnetic particle technique. To investigate fatigue failure it was necessary to determine the inservice loading of the brake rod. The broken rod was replaced with a new rod and loading conditions were applied. Four strain gauges were attached at a distance of from the lower end, located 90 degrees apart around the circumference of the rod. Readings were taken during manual release and application of the brake and during emergency application of brake. The results showed that in addition to the expected direct tensile stresses at gauge positions there were substantial stresses due to bending when the brake was operated. The magnitude of stresses varied to such an extent that for the one farthest from the drum there was a change from tension to compression as the brake was released. The rod was not designed for such alternating bending loads. The rod was designed with a factor of safety 6.1 for tensile stress. But when alternative bending stress are induced, failure was inevitable. It was also found that mild steel bearing pad surfaces were badly worn as lubrication was not effective at bearings. This was also due to the unexpected bending stress which progressively squeezed the lubricant out of the gap. Follow up A National Committee for Safety of Manriding in Shafts and Unwalkable Outlets was formed and first met on 3 December 1973. The Committee produced two reports and an addendum. The National Coal Board carried out a programme to examine the braking and safety systems on all of its mine winders and modified them in accordance with the recommendations