Pivot

The Encyclopaedia has now been locked; contributors must log in to make changes. [more]

Difference (from prior major revision) (author diff)

Changed: 1c1

Once a location (usually a station, but not always) has been pegged it is possible to perform a rotational movement around it, as if it was the centre of a circle or spiral. As most moves in Mornington Crescent are linear, a well-timed pivot can get round obstacles that could not be circumvented in any other way. When performing such a manoeuver, it pays to pay close attention to line velocity and the current level of helical stress; if either is excessive, the pivot manoeuver may fail badly. A Crossmead Spiral or Pettengale Sweep is a (usually) safer methor to approximate a pivot using standard linear rather than rotational moves, and the hazards of incorrectly executing a Crossmead Spiral are already well-documented.

Once a location (usually a station, but not always) has been pegged it is possible to perform a rotational movement around it, as if it was the centre of a circle or spiral. As most moves in Mornington Crescent are linear, a well-timed pivot can get round obstacles that could not be circumvented in any other way. When performing such a manœuvre, it pays to pay close attention to line velocity and the current level of helical stress; if either is excessive, the pivot manœuvre may fail badly. A Crossmead Spiral or Pettengale Sweep is usually a safer method to approximate a pivot using standard linear rather than rotational moves, and even a Crossmead Spiral carries several well-documented hazards if not executed correctly.

Changed: 5c5

Categories: A to Z

Once a location (usually a station, but not always) has been pegged it is possible to perform a rotational movement around it, as if it was the centre of a circle or spiral. As most moves in Mornington Crescent are linear, a well-timed pivot can get round obstacles that could not be circumvented in any other way. When performing such a manœuvre, it pays to pay close attention to line velocity and the current level of helical stress; if either is excessive, the pivot manœuvre may fail badly. A Crossmead Spiral or Pettengale Sweep is usually a safer method to approximate a pivot using standard linear rather than rotational moves, and even a Crossmead Spiral carries several well-documented hazards if not executed correctly.

[SM]

Categories: A to Z