AGMA 05FTM17-2005 pdf download.Influences of Bearing Life Considerations on Gear Drive Design by: F.C. Uherek, Rexnord Geared Products.
By its nature, a catalog design gear drive is not developed with a known set of load conditions. The designer does not have the luxury of the certain knowledge that it will be operated only at moderate speeds occasionally on Sundays during months that do not have a letter R in them. Catalog speed ranges run from 1800 to 100 rpm. Application or service factors per AGMA standards range from 1.0 to 2.0for various applications. Customers may specify additional requirements such as increased bearing life or limited cooling options that also influence box size. The unit design must be capable of operating at any of these conditions.
For the purposes of this paper, we will make the assumption that the gearing is the limiting member in the drive. Bearings, shafting, and other components, keys, fasteners, etc. will be selected and sized to exceed the rating of the gears. Although optimal, this gearing only limitationis sometimes difficult to achieve in practice when one is balancing the competing options of having a wide variety of ratios and maximum flexibility combined with minimum variation in part dimensions and inventory of parts. For this study, we will assume that we can pick the optimum bearing size regardless of size variation across ratios and multiple reduction drives.
The gear drive will be operated for 60 Hz service at 1750 rpm input speed. Ambient temperature range is -17 °C to + 38 °C. Altitude is assumed to be less than 700 meters. The effect of sump temperature is reviewed by looking at both a 28 °C rise anda 55 °C rise in sump temperature above the ambient of 38°C. The control in temperature rise can take the form of forced air cooling, water cooling coils, or dedicated pump and oil-to-water heat exchangers.
Gear Drive Designs
In 1997 AGMA was involved in a worldwide study to compare and contrast the various methods used to determine the load distribution factor KHβ. To further efforts in this area, three parallel shaft gear drives were developed to test various assumptions in the calculation models. These gear drives were uilized as the design in the analysis.
The single reduction gear unit has a space envelope of 883 mm wide by 635 mm tall by 1021 mm deep shaft-to-shaft with the following key dimensions listed in table 1.
Based on the above geometry, gear ratings were calculated to AGMA 2001-D04 using the AGMA Gear Rating Suite Version 2.2. Setting required gear life to 10000 hours as recommended in AGMA 6010- F97, and setting service factor equal to unity,we calculate a unit rating of 990 kW at 1750 rpm input speed per AGMA 2001-D04.
The double reduction unit has a space envelope of 1048 mm wide by 543 mm tall by 870 mm deep shaft-to-shaft with the following key dimensions listed in table 2.
Based on the above geometry, gear ratings were calculated to AGMA 2001-D04. Setting required gear life to 10000 hours as recommended in AGMA 6010, and setting service factor equal to unity, we calculate a unit rating of 308 kW at 1750 rpm input speed per AGMA 2001-D04.AGMA 05FTM17 pdf download.