Vibration Sideband Modulations and Harmonics Separation of a Planetary Helicopter Gearbox with Two Different Configurations

Table 2

Shaft and gear mesh frequencies.

	Frequency of interest (Hz)	Three planets	Four planets	Relationships and calculations
Stage	Input shaft frequency	100.00	100.00
	Pinion/bevel mesh frequency	1900.00	1900.00	Number of teeth of the bevel pinion times input shaft frequency
	Bevel gear shaft speed	26.76	26.76	Input shaft frequency/1st-stage reduction ratio
Stage	Carrier frequency (output arm speed)	5.73	5.73	Input shaft frequency/overall reduction ratio
	Epicyclic mesh frequency	567.71	567.71	Number of teeth of the ring gear times carrier frequency
	Planet pass frequency	17.20	22.94	Number of planets times the carrier frequency