On all HBF drives:

  Check the pre-tension of the plate springs. The coupling must be turned far enough so that the plate springs (including the upper and lower discs) are the right length:

─     For connection of the HBF drive on the friction wheel side: H = 59 mm.

─     For connection of the HBF drive on the travel motor side: H = 49 mm.

  If the plate springs are tensioned too much or too little: readjust them.

On all HBF drives:

Example of damage on the friction wheel.

  Inspect the running surface of the friction wheel. The running surface may not be cracked, heavily worn or otherwise damaged.

  If the running surface of the friction wheel is no longer in good condition: replace the friction wheel. See Changing the friction wheel.