Since the development of the belt drive, belt manufacturers have introduced new measuring methods for adjusting the belt to the correct pre-load. In the past the deflection of the belt has been measured with a given load. Nowadays the resonance frequency on a free oscillating length will be measured. This has been proven as a more precise method.

Tests have shown much less spread in pre-load applying the frequency method and a smoother running belt is achieved. For this reason a new maintenance instruction "Adjusting the drive belt" has been created. This instruction also shows a cheap measuring method applicable for the belt drive of the rotary engines.

The much more precise belt pre-load implies a longer operating life. It is recommended to accomplish the maintenance instruction before the next annual C. of A. inspection.


Affected types and the corresponding TNs:

ASW 22 BLE 50 R	TN 12
ASH 25 M / Mi	TN 27
ASH 26 E	TN 15
Maintenance Instruction

Hints and Tips for adjusting the drive belt

Measuring the resonance frequency with a tuner

If a tuner shall be used instead an expensive frequency measurement instrument, the KORG tuner CA-30 can be recommend. This instrument is available for EUR 30.- in a music store. Instruments like this need a little moment for gathering the frequency. After picking the belt, the belt oscillates only for a short moment. It operates better, if the belt will be picked for several times close behind one another.