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Miscellaneous: Operating Equipment & Practices

Maintenance of the Permanent Way: misc_equip240

Typical Hallade Record showing places where whitewash was dropped

Scan of the chart paper from a Hallade Recorder. The instrument recorded the longitudinal, transverse and vertical movement and had two external traces that were used to record the Whitewash drop (bottom) and location marker (top). The speed and milepost numbers have been added subsequently. The longitudinal movement can occur from a variety of causes, including the application of brakes, so may not necessarily indicate an issue with the track. The transverse movement is probably the most important when looking for incorrect cant on the permanent way. When travelling around a curve there will be an outward thrust which will vary depending upon the sharpness of the curve and the speed of the train. Increasing the height of the outer rail (cant) counter-acts this thrust and a perfectly adjusted rail will carry the weight of train at the average speed equally on both the rails. The vertical movement will be caused by slacks in the road, low or high joints, hanging sleepers, or excessively sharp gradients.

Robert Ferris