1 Introduction
2 Test specimen
Sun | Planet | Ring | |||
---|---|---|---|---|---|
No. of teeth | \(\mathrm{z}\) | – | 26 | 23 | 74 |
Pressure angle | \(\alpha _{n}\) | ° | 27 | ||
Module | \(m_{n}\) | Mm | 3.91 | ||
Helix angle | \(\beta\) | ° | 15 | ||
Active face width (each half) | \(b\) | Mm | 21 | – | |
– | 19 | ||||
Transv. contact ratio (Standard design) | \(\varepsilon _{\alpha }\) | – | Approx. 1.5 | ||
Overlap ratio (one helix bank) | \(\varepsilon _{\beta }\) | – | Approx. 0.5 | ||
Centre distance | \(a\) | Mm | 99.156 | ||
No. of planets | \(N\) | – | 5 | ||
Quality of total profil deviation (min/max) [6] | \(F_{\alpha }\) | – | 2/4 | 2/6 | 1/3 |
Quality of total helix deviation (min/max) [6] | \(F_{\beta }\) | – | 4/6 | 2/6 | 8/8 |
Quality of total index devation (min/max) [6] | \(F_{P}\) | – | 4/4 | 1/4 | 4/6 |
3 Test rig and test matrix
4 Instrumentation, data collection and sensor calibration
5 Data evaluation and computation of load sharing
6 Results
7 Conclusion
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The load share factors determined under quasi-static condition are applicable for a wide operational range of speed and torque. Dynamic effects on the load sharing behaviour have to be considered only at very high speeds (also depending on the ressonance area of the gear meshes).
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Although high-precision gears and components are used in this study, the results show relative large differences in load sharing under low load when comparing the individual planets. Thus, including the tolerance chain into the design process is recommended.
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At high speeds and low loads, the load sharing behaviour is significantly influenced by the vibration behavior of the drive train. Resonance areas can lead to increased load share values and amplitudes. The operational range of the planetary gearbox should be checked for such ressonance areas (tooth numbers and masses) to avoid them during continous operation.
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Not only the gear mesh affects the load share under high rotational speeds, but also the movement of the sun. This coincides with previous experiments in the literature [12]. A tradeoff between the adjustability of the sun to improve the load sharing for lower speeds and a reasonable bearing arrangement for high speeds is necessary.