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Have servo drives eliminated ball-detent torque limiters from new OEM designs?

Posted: Fri Feb 09, 2018 1:39 pm
by ElectricalEngineer97
I have been following the advancements of servo drives for about 20 years. It seems that ball-detent torque limiters were once necessary to prevent extensive damage CNC applications. Now, it seems, most OEM designers don't use these couplings any more because the servo drives are sophisticated enough to detect torque spikes early, and to stop motion quickly, enough to prevent serious damage. Is anyone still designing with ball-detent torque limiters any more?

Re: Have servo drives eliminated ball-detent torque limiters from new OEM designs?

Posted: Fri Feb 09, 2018 4:32 pm
by Taylor
I agree that servos have become much more sophisticated, so in the lower torque applications there is less of a need for the old style torque limiter but there are still many applications that aren't driven by servos especially high torque applications like conveyors or mining machines. Also many times it depends upon the reduction being used and how fast the motor would see the torque spike. In those instances the torque limiter is located very close to the final drive point versus further up the drivetrain near the motor.

Re: Have servo drives eliminated ball-detent torque limiters from new OEM designs?

Posted: Thu Jul 05, 2018 7:39 am
by MassMechanical
I was designing and selling torque limiting clutches for 30 years before I was selling gearboxes. Back then, machines were designed with line shafts and the mechanical torque limiter was very popular in OEM applications. As servo drives became less expensive and more popular, the mechanical torque limiter started to lose it popularity and its share in the power transmission market. For extremely lightly loaded machines, the current limit on the servo can detect and stop catastrophic machine crashes before they can cause any damage. For faster machines and heavier loads, mechanical torque limiters still make sense. In some cases the current limit may be too late. I always told customers that a current limit was like shutting off the car engine after you have hit the brick wall. A well-made precision torque limiter like the R+W SK series can detect a torque spike and disengage the load before any current limit.

Re: Have servo drives eliminated ball-detent torque limiters from new OEM designs?

Posted: Fri Jul 27, 2018 11:17 am
by Taylor
If we are talking large torque, how about shear pins? Some of the mills still use those somehow. :roll:

R+W's SK looks like they have a pretty wide range. Torque to 2800Nm with precision.

I guess there are many ways to solve a problem... mechanical, electrical, or something else. We just try to pick the best way depending on the situation.