Torque in a Planetary Geartrain
In part (a) of the previous example, the carrier and sun gear are driven by engines producing 2 hp and 5 hp, respectively (Figure 8.42). Determine the torque applied to the shaft of the output ring gear.
Approach
To calculate the torque applied to the output shaft, we recognize that, to balance the power supplied to the geartrain, the output shaft must transfer a total of 7 hp to a mechanical load. To apply Equation (8.5)
P = T_{ω} (torque) (8.5)
in dimensionally consistent units, first convert the units for power from horsepower to (ft ·lb)/s with the conversion factor in Table 7.2.
Table 7.2
Conversion Factors Between Various Units for Power in the USCS and SI
(ft . lb)/s | W | hp |
1 | 1.356 | 1.818×10^{-3} |
0.7376 | 1 | 1.341×10^{-3} |
550 | 745.7 | 1 |