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Five sailors from "Hisse et Oh " french forum ordered a Hurd, ELA45-300-070-12 actuator. Delivery en of May. We will let you know about installation and configuration with Pypilot.
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I have tested the hurd ELA35-300-030-12-L
It is a peace of crap compared to our Pcnautic (HB/Pelagic)
Noisy, no strength, the ball screw is to small for the job.
You have to divide the specs by at least 2 I guess compared to the specs from Pcnautic HB Pelagic type.
Maybe it is better to compare the more heavy units.
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Are you sure any of these actuators use a ball screw? I suggest seems they use a cheaper lead screw. If it is actually a ball screw, then this is already a good deal if it is actually in stainless 316.
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theoretically you are richt and would a ball screw be preferable, in practical use I have not seen yet a ball screw type that could beat our lead screw drive in performance and efficiency.
One off the big disadvantages is that you can move the push rod from the bal screw types, if there is any better efficiency with the ball screw types it gets lost by far because of that.
The type and size of the used motor has much more influence on the efficiency in combination with the exact calculated lead screw angle, size and pitch so you have the best performance and efficiency at the right power and speed.
Yes the Hurd has a ball screw and our drive a lead screw, the hurd ELA35-300-030-12-L specified as 300N can not even handle 15.5kg I had to test with a lower weight I had and that was 12.8 kg ,he can barely handle that with around 3A @ 12V, our drive specified as 200N@45mms can easy handle that at 2.7A@12V, the max power off our drive is around 35kg.
The best performance our drive has is with a 200N load (=+/- 20kg)@ 45mms = 4A @ 12V
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Any unit you can backdrive means it has lower friction and thus higher efficiency. If this is the case, then they do need a brake (reverse clutch) to fully realize this potential so they can hold position which pypilot does not really fully support. This would complicate things but the efficiency gains of ball screws are potentially large.
Electric motors are most efficient with lighter loads that only reduce free running speed by 10% or so. So this "hurd" actuator may well be more efficient at much lighter loads? Did you try 3 or 5kg? It seems strange that it cannot even move half its rating (Unless it expects 24 volts or something), but in general ball screws are significantly more efficient but would need software support and a brake to fully realize it, especially if there is significant weather helm.