Page 259 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Gear and Coupling Best Practices Be st Practice 4.1

Table 4.1.1 Simple planetary data
Kind of arrangement Fixed member Input member Output member Overall ratio Range of ratios normally used

Planetary Ring Sun Cage T 3 3:1-12:1
þ1
T 2
Star Cage Sun Ring T 3 2:1-11:1
T 2
Solar Sun Ring Cage T 2 1.2:1-1.7:1
þ1
T 3
Key
T 1 ¼ number of planet teeth
T 2 ¼ number of sun teeth
T 3 ¼ number of ring teeth

Table 4.1.2 Compound planetary data
Kind of arrangement Fixed member Input member Output member Overall ratio Range of ratios normally used
Compound planetary Ring Sun Cage T 3 T 11 6:1-25:1
þ1
T 2 T 12
Compound star Cage Sun Ring T 11 T 3 5:1-24:1
þ1
T 2 T 12
Compound solar Sun Ring Cage T 2 T 12 1.05:1-2.2:1
þ1
T 3 T 11
Key
T 2 ¼ number of sun teeth
T 3 ¼ number of ring teeth
T 11 ¼ number of first-reduction planet teeth
T 12 ¼ number of second-reduction planet teeth

The key reliability factors concerning planetary gears are
presented in Figure 4.1.9.

1. Complicated assembly
2. Equal planet load distribution
3. High planet shaft loads
4. Rotating ring gear balance and vibration
5. Gear assembly seizure if foreign objects enter mesh

Fig 4.1.9 Planetary gear train reliability factors

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