A pole changing type squirrel cage motor used in derricks has four, eight and twenty-four poles. In this, the lowest speed is used for

A pole changing type squirrel cage motor used in derricks has four, eight and twenty-four poles. In this, the lowest speed is used for

Right Answer is:

Landing the load

SOLUTION

  • When the boom is lowered, the load will both travel away from the crane and become lower.
  • The mechanical load brake is a key component of crane safety.
  • It serves as a secondary braking mechanism of the crane hoist, controlling the lowering speeds of rated loads and preventing loads from free falling.
  • All of the torque of a hoist motor is applied to lifting loads.
  • In the lowering phase, however, gravity takes over, and the mechanical load brake is in place to counteract the gravitational pull to ensure a safe, controlled descent of the load.
  • Hence low speed is preferred for lowering the load because precise and smooth control is required for placing the load in its given location or position.

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