Shaft torque
The rated torque is a measure of tooth wear and is the torque level at which a normal spline life of 2 x
109 shaft revolutions can be expected. The rated torque presumes a regularly maintained minimum level
of lubrication via a moly-disulfide grease in order to reduce the coefficient of friction and to restrict the
presence of oxygen at the spline interface. It is also assumed that the mating spline has a minimum
hardness of Rc 55 and full spline depth. The rated torque is proportional to the minimum active spline
length.
Maximum torque ratings are based on torsional fatigue strength considering 100.000 full load reversing
cycles. However, a spline running in oil-flooded environment provides superior oxygen restriction in
addition to contaminant flushing. The rated torque of a flooded spline can increase to that of the
maximum published rating. A flooded spline would be indicative of a pump driven by a pump drive or
plugged into an auxiliary pad of a pump.
Maintaining a spline engagement at least equal to the Pitch Diameter will also maximize spline life. Spline
engagements of less than ¾ Pitch Diameter are subject to high contact stress and spline fretting.
Shaft torque for tapered shafts
The rated torque is based on the contact pressure between the shaft and hub surfaces with poor surface
contact areas. With an increased quality of the contact areas, the contact pressure between the shaft and
hub is increased and allows higher torque to be transmitted.
When a key is used for orientation of the hub on the shaft in conjunction with poor quality contact
surfaces, the transmitted torque will drop significantly. This is due to the key carrying the torque, which
limits the shaft torque carrying capability.
Maximum torque rating is based on an ideal contact area of 100 % and the retaining nut properly
torqued. This allows for the highest contact pressure between the shaft and the hub.
Basic Information
H1 Axial Piston Pumps, Single and Tandem
System design parameters
34 |
©
Danfoss | April 2017 11062168 | BC00000057en-US0602
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