Which simple machine is a winch?
June 10, 2009 2:19 PM   Subscribe

SimpleMachinesFilter: which is a winch?

Given the categorization of simple machines into these 6 types:

• lever
• inclined plane
• wedge

• screw
• pulley
• wheel and axis

would you classify a winch as a pulley or a wheel and axis type of simple machine? Or is it a combination of simple machines?

Also, would it be correct to say that the difference between the first three types of simple machines and the second three is that the second three multiply torque?

(If there's something screwy [so to speak] about the classification system in the first place, please sound off about that as well.)

Thanks in advance!
posted by slappy_pinchbottom to Science & Nature (16 answers total)
a lever
posted by HuronBob at 2:25 PM on June 10, 2009

posted by HuronBob at 2:25 PM on June 10, 2009

The wikipedia page on wheel and axle shows a winch.

Given that, many users of a winch wrap the rope around a pivot point, which would act as a pulley.
posted by smackfu at 2:26 PM on June 10, 2009

I am with HuronBob. It's effectively a lever. (are we doing someone's homework? if so you must let us know what grade we get)
posted by caddis at 2:49 PM on June 10, 2009

Don't get too reductionist or you'll end up discounting the screw as a "spiral inclined plane."

Real life winches sometimes use a pulley, but sometimes are just a reel. The reel may or may not have reduction gears. Most electric or hydraulic powered reels have reduction gears since the motor RPM is so fast. If you are talking about a hand-crank winch, then it might have a multiplier gear (like a fishing reel).
posted by markhu at 2:57 PM on June 10, 2009

let's make it simple...let's not involve any gears (since the OP didn't mention that). If you think about it, the handle of the winch is what does the work. Without the handle, using just the hub on an axis, it would not reduce the work involved....

Lever... again I say Lever!
posted by HuronBob at 2:59 PM on June 10, 2009

Yea! Lever!
posted by pointilist at 3:09 PM on June 10, 2009

If this is a lever, then nothing is ever a wheel and axis.
posted by smackfu at 3:17 PM on June 10, 2009

depends on your definition of a winch, but I am inclined (ha!) to agree with smackfu.
posted by Chris4d at 3:40 PM on June 10, 2009

Combination of lever and wheel and axis. Wheel and axis gives you the ability to reel in the rope/cable, while the lever makes it easier to do.
posted by Simon Barclay at 4:05 PM on June 10, 2009

If this is a lever, then nothing is ever a wheel and axis.

Quoted for truth. Seriously, people.
posted by 0xFCAF at 4:17 PM on June 10, 2009

As wikipedia points out, the list of six simple machines is somewhat arbitrary and traces back to the Renaissance. You could reduce the traditional list by considering the wedge to be a moving inclined plane. The screw could be considered a helical inclined plane. The wheel and axle and pulley can be considered circular levers, which leaves only the lever and the inclined plane as the most basic simple machines. So calling a winch either a specialized form of lever or a wheel and axle are both acceptable.
posted by JackFlash at 4:34 PM on June 10, 2009

The word winch comes from the Middle English winche, meaning roller or wheel. If you want to get etymological about it.

Let's pretend the winch has a small hub and a wheel on one side instead of a crank/handle. Would you still call it a lever? The wheel magnifies the force of your muscles the same as the crank would (by increasing the distance at which you're applying torque to the axis).
posted by pmbuko at 8:13 PM on June 10, 2009

You're not doing anyone's homework -- you're actually helping me create homework for others! I'm editing a bit of physical science courseware, and this has come up as a sticky wicket, so to speak.

While most here seem to be fairly definitive about their opinion, nobody has yet presented an argument that seemed authoritative, to me, for a single choice. And that was basically my experience trying to Google up the answer, too.

I think I may have to go meta on this one (as it were) and let the students know that there's a difference of opinion on the issue, and that the terms are (as JackFlash states) somewhat arbitrary; however, I'd rather not if I can help it, since there doesn't seem to be a high tolerance for ambiguity in this particular course. Any more authoritative arguments or sources would be very welcome (not to sound like an ingrate to previous commentors, thanks muchly for your input also! You all make sense to me, which is the problem.)

For those who believe it's a lever, let me ask you this: where is the fulcrum?
posted by slappy_pinchbottom at 9:50 PM on June 10, 2009

Please teach your students that science, properly done, sometimes still has ambiguity. You would be my hero.

The fulcrum of the lever-handle is the axis of the wheel. It's like a crowbar in that the applied force and the load are on the same side of the fulcrum.
posted by fantabulous timewaster at 3:21 AM on June 11, 2009

Thanks, fantabulous! That way of formulating it synthesized the previous comments for me in an illuminating way, though I see Simon Barclay said pretty much the same thing above. I may steal that first sentence word-for-word.
posted by slappy_pinchbottom at 12:32 PM on June 11, 2009

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