Definition - What does Impulse Coupling mean?
Impulse Coupling is a mechanical device installed between the magneto power and engine drive on most of the rotary magneto installations. The main function of the device is to intensify ignition spark at a low rotative speed to aid in the starting of the engine. It is solution for engine starting problems. It is smartly constructed as its construction in addition automatically offers a source for retarding ignition spark during the starting period and hence reduces the possibility of injury to the operator and damage to engine because of engine backfiring.
Petropedia explains Impulse Coupling
Impulse Coupling chokes off the acceleration of magnet and ignition timing at TDC in magneto jazz up voltage and aids in igniting mixtures at TDC. Spring loaded flyweights present in Impulse Coupling react due to the centrifugal force when the engine starts, so that they do not catch on stop pin. While this takes place, the engine directly drives the magneto and the timings are returned to normal setting. As the coupling contains some moving parts, it is required to be disassembled and then inspected attentively after every 500 hour of the magneto cycle. The failure of the Impulse Coupling results in the failure of the engine and sometimes the parts of the coupling are dropped into the engine gearbox and cause catastrophic destruction to the engine.