torque calculations
Submitted: Thursday, Feb 24, 2011 at 15:31
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Member - bungarra (WA)
Trying to calculate the torque requirements for a worm drive / dc motor gearbox calculation if I build this boat loader
Google tells me to multiply distance by the weight to shift to get pounds/foot then convert to Nm (which is what most of the specs. seem to use on the net loking for the dc motor
Image Could Not Be Found
using this diagram i get 3085 ponds/foot. Google conversion gives me 4,192 Nm
am I doing something wrong?..........where do I source a suitable worm drive reduction gearbox with a 12V dc motor suitable?
Thanks .
.hopefully someone can point me in the right rirection
Reply By: Member - bungarra (WA) - Thursday, Feb 24, 2011 at 15:32
Thursday, Feb 24, 2011 at 15:32
my picture looks a bit hard to read
if you cannot read the figures it is 4.5m on the rope, 3.8 m boat length and 95 kg in weight
Thanks
AnswerID:
446447
Reply By: briancc - Thursday, Feb 24, 2011 at 16:21
Thursday, Feb 24, 2011 at 16:21
Not that easy unfortunately. Line pull is what you need to start. If you were to lift the pointy end vertically, you would be looking at about half the 95kg. Worst case, call it 95 which is about 950N. Now because the lift isn't vertical, you need the component in the direction of the rope. That angle with the vertical is around 57 degrees, with cosine (trig) of around 0.54. This will make the line pull 950/.54 = ~1760N. Now the torque required is going to depend on the drum diameter / radius of the winch. This is where the T=FxD formula kicks in. Say a 50mm radius (wild guess) 1760x0.050 = 88Nm. I think. Needs a
check. Be aware of the different radii that the winch can work at. Also the number may change as the boat goes onto the roof, although I don't think it would get larger.
AnswerID:
446453
Reply By: ob - Thursday, Feb 24, 2011 at 17:27
Thursday, Feb 24, 2011 at 17:27
Hi bungarra, I certainly wouldn't argue with briancc's calculations, the first paragraph left me behind, but maybe try Kevrek, the makers of those small slewing cranes you see on the back of utes and small trucks. The slewing function is performed by a worm and wheel setup. They are usually connected to a smallish hydraulic motor but I can't see any reason why you couldn't drive it with a 12v motor like they use to power the "Powerpak" that drives the whole setup. I would think the smallest cranes (500kg I think) worm drive would do. Maybe give Kevrek a call.
ob
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446460
Reply By: Eric Experience - Thursday, Feb 24, 2011 at 21:09
Thursday, Feb 24, 2011 at 21:09
My mental arithmetic says 200KG line pull would be enough, so any 1000LB boat winch will do the job. Aldi had them for about $300. Eric
AnswerID:
446478
Reply By: Roughasguts - Friday, Feb 25, 2011 at 11:36
Friday, Feb 25, 2011 at 11:36
You could just use a boat winch! with handle, only about 130 Bucks from Bias Boating or super cheap.
Then no worries sorting out power and wiring.
Or hook your 12V electric motor up to the boat winch.
Cheers.
AnswerID:
446523