This the torque that you can use continuously for 20,000h at nominal speed and with ambient temperature 25°C. Not exceeding this value ensures that the gearbox does not lose precision and can work for a very long time (years, normally). Using 15% less than the nominal torque value in S1 cycle theoretically provides an even longer lifetime, as calculation gives an unlimited result.
It should only be used 10% of the gearbox lifetime (anyway less than 2,000h) because it slightly wears the gears, and because exceeding this duration would create the conditions of a fatigue breakage. It is important to note that the product will slightly lose precision over time when the acceleration torque is used frequently. Applications that need to preserve a very high precision in the long run (applications with high positioning accuracy or fast reversals where backlash can lead to breakage) need to avoid using the acceleration torque too frequently and should combine the rated torque with an application factor (see below). In many applications, allowing just a few seconds to the application start can prolong the gearing lifetime significantly.
Using such value will not wear the gears or make you lose precision because it only lasts seconds in the product life. The gearbox was designed to handle it 1,000 times. Exceeding this value can cause irreversible damage to the internal components, as it applies a high bending strength on the gears teeth and strong efforts on the shafts and needle bearings.
It is the torque that results from your different needs using the formula:
Rated torque = average torque x application factor x temperature factor