Maximum permissible (output Mk0 / peak Mkmax) torque for 8LS motors with externally connected gearbox 8GP

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1

In 8LS motors documentation the (shared values or General values) section are not complete, where the Max. permissible output torque MK0 [Nm] and Max. permissible peak torque MKmax [Nm] can not be found since the motor is not initally provided with gearbox unlike the 8LV motors. In case of adding a gearbox such as 8GP to an 8LS motor, those values can be calculated as following:

Mkmax = the maximum torque of the motor * gear ratio (Mmax * gear ratio)

For Mk0 the standstill torque (M0) needs to be used but for the dT60 curve (yellow in the attached picture) as there is derating of the nominal values from the motor when a gearbox is attached. Therefore,

Mk0 = (M0 dT60 * gear ratio)

8LS curve
8LS curve1041×426 53.8 KB

2

I think it’s important to check the gearbox torque in datasheet , because although the torque offered by the motor and the reduction ratio can be calculated as you mention, in many cases it could be that the reducer is not prepared to have this output torque.

In some applications the required torque could be very low, but the inertia ratio must be taken into account, so a gearbox with a high gear ratio but with a low output Tmax can be chosen just to have a better inertia ratio in the mechanism.