Planetary Gearboxes Gear Selection Selection Example 2: Concrete Pump driven by Electric Motor with Variable Frequency Drive. Known data: Power input via electric motor (4 pole - IEC 160 B5). » Installed power 11 kW. » Actually transmitted power 9.5 kW. » Motor peak factor = 1.6 limited by VFD. » Input speed n = 1430 rpm. 1 » Output speed n = 4 rpm. 2 » Power output via shrink disc, torque arm length = 1 m. » Duty cycle: continuous operation for 24 hours, 3 start-ups per day. » Ambient temperature 30°C, horizontal mounting position. » Required life: 6000 hours/year for 20 years = 120000 hours. » OK OK OK 42 www.jbj.co.uk/planetary-gearboxes.html #DriveLineHarmony OK OK 2.1 Ratio: n 1430 1 u = = = 357.5 n 4 2 2.2 Transmitted torque: T = P x 9550 = 9.5 x 9550 = 22681 Nm 2 n2 4 2.3 Application factor: K = 1.2 (from table 1, page 41) A 2.4 Radial load on output shaft: Not applicable due to adequate length of torque reaction arm). 2.5 Shock factor: Not applicable, as above. 5 2.6 Service life: n x h = 4 x 120000 = 480000 = 4.8 x 10 2 5 2.7 Life factor gears: f = 0.59 (from graph 1, page 41, for n x h = 4.8 x 10 ) G 2 2.8 Life factor bearings: Not applicable, as 2.4 above. 2.9 Required torque rating: T req. = T x K x 1 = 22681 x 1.2 x 1 = 46131 Nm 2 2 A f 0.59 G 2.10 Adjusted radial shaft load: Not applicable, as 2.4 above. 2.11 Selected gearbox: PS 420 - L4 - P24 - 360 - E16 ratio 360:1; T = 42000 Nm, T = 51000 Nm, T = 58000 Nm nom act peak P = 12 kW, P = 30 kW th max 2.12 Verification: T req = 46131 < T act = 51000 Nm 2 2 Gearbox: T peak = 1.6 x 11 x 9550 = 42020 Nm < 58000 Nm 2 4 Shrink disc: T peak = 42020 Nm < 55000 Nm 2 P = 11 kW < P = 30 kW peak max P = 9.5 kW < P cor = 12 kW x 0.86 x 1 = 10.3 kW th (with f = 0.86 from table 3, page 40, f = 1 from table 4, page 40). t v
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