To check the brake, the reference gap between the brake bearing shield and anchor plate is measured, as well as the brake lining thickness.

A step (for the O-ring) makes the air gap (distance between brake bearing shield and anchor plate) difficult to access. Therefore a reference gap is measured outside on the motor in order to obtain information on the width of the air gap.

Overview:

If the reference gap is wider than permitted, the brake must be readjusted. If the minimum brake lining thickness is reached, the fan blade with brake lining must be replaced.

If the width of the reference gap is within the permitted range but usage behaviour leads to the expectation that the reference gap will be wider than permitted before the next regular inspection, the fan blade with brake lining must be replaced now.

  Take off the fan cover.

  Measure the distance between brake bearing shield and anchor plate.

  If the reference gap is larger than 3.7 mm: adjust the brake. See Setting the air gap on the brake.

  Check the thickness of the brake lining with a calliper.

  If the brake lining is less than 2 mm thick: replace the fan blade with brake lining. See Replacing the fan blade with brake lining and anchor plate.

The area between the brake bearing shield and the anchor plate (reference gap) is protected from dust by an O-ring. The O-ring must not become damaged or missing.

  Check the O-ring (between brake bearing shield and anchor plate).

The O-ring must not be torn, dented or damaged in any other way or be missing completely.

  If the O-ring is damaged or missing, fit a new O-ring. See Replacing the O-ring, plate springs, compression springs and feather key.

  Attach fan cover.