Hand Cranking for a Assembly fixture rotation 3

[Gopalakrishnan C]

Hi,

I need a hand cranking methods to rotate by 1600NM. I was searching in Boston gears but unable to find out.
The fixture rotation rpm is 0.5.
Thanks!

 

[VEBill]

1600 newton-meters (torque) at 0.5 RPM, by hand? Is that about 0.1 horsepower ?

It would get tiring after a bit.

 

[rb1957]

I think you want a speed reduction gear-train … 80Nm at 10rpm would drive 1600Nm at 0.5rpm

another day in paradise, or is paradise one day closer ?

 

[3DDave]

Yeah - the HP continuous output of a pair of human's legs for someone in good shape is about 0.1Hp. Hand cranking will work for about 10-30 seconds or so for anyone not on a sailing team.

They make gear stages so just add them together if the input force is too high, but each adds friction and eventually that goes south. Lowering the input force means increasing the input rate, so you get a different set of metabolic problems.

 

[moon161]

Even the vague possibility of this being a 737 application is slightly disturbing to me.

 

[rb1957]

why "737 application" ?

another day in paradise, or is paradise one day closer ?

 

[moon161]

Cause it's a high torque handcrank mentioned in an aicraft discussion board. It makes me think of the cursed 737 max trim crank.

 

[3DDave]

If the stab is turning 1/2 RPM then things have totally gone south. And selecting from Boston Gear on an aircraft application is the wrong place to begin.

 

[Gopalakrishnan C]

Hi 3DDave

I have chosen the Haacon Type 242.3 Manual crank to do this.
Please give your comments
Thanks!

 

[3DDave]

Wait - you have a random design which seems impractical based on power availability from any normal person and you would like me to go and find documentation for a random some mechanical thing? To say what about it, exactly?

 

[MintJulep]

I guess that he wants you to check that it's ok to support the torque selected by a random person (me) in the internet
based on a guess.

 

[VEBill]

1600 newton-meters (torque) at 0.5 RPM.

When you see torque and RPM, you should instinctively calculate the associated power.

Wolfram Alpha says that's 0.112 hp.

If it's continuous, then you'll need one of these (offered as a visual aid to assist with clarifying thoughts):

If it's just to adjust a fixture once in a while, then either back away from the 0.5 RPM requirement, or add an electric motor.

 

[monkeydog]

3D Dave,
It looks like you have an "Action Item". Just be glad he didn't put in a due date.

 

[Gopalakrishnan C]

Sorry for the in-proper information!
Actually i need to rotate a heavy loaded fixture overhanging on an axis. And this one needs to be rotated by hand crank method.
I calculated the maximum torque 1600 NM.
And it is not a continuous rotation.
I searched and found the Manual crank (Haacon Type 242.3).

 

[rb1957]

I think you're misleading us with "output rpm = 0.5", when you add "it is not a continuous rotation" (which is implied by stating an output rpm).

I think you should say you have to rotate the mass through 180deg? in 15sec?

Sketches still very simplistic. If you think you've found a handle to work, why ask us ?

another day in paradise, or is paradise one day closer ?

 

[IRstuff]

Is this for school?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[VEBill]

Ideally, a fixture would be designed so that the axis of rotation is in-line with the system's center of mass. Then the item could be easily rotated with a fingertip.

If that's impossible here, then it's a lifting exercise. The rotation is essentially incidental. So one should be searching for a winch assembly. Or a jack.

...And redundant straps in case someone bumps into the rachet pawl.

 

[SAITAETGrad]

Aerovelo Human-Powered helicopter is maybe the ultimate optimization for this.

Aerovelo Atlas - Sikorsky Prize

This is a forum for practicing engineers. School projects are not generally welcome.

 

[Gopalakrishnan C]

@SAITAETGrad
This is not for a School project!
I am designing a tool to rotate and position the heavy equipment
I am finding difficulties to calculate the torque for eccentric load of 680kg.
The axis of rotation is horizontal and the distance between Center of mass and Center of rotation is .25m

I am using τ=Iα
Here is the confusion, when i calculate Alpha:
I am using manual crank and there will not be any continues rotation. I just want to rotate and position the equipment. In this case when i change the rotational speed my output torque value is drastically varying.

If any one can give me the clarity that how to calculate the Speed of rotation for manual crank? Or we simply take 60RPM for Torque calculation?

Thanks!

 

[VEBill]

A manual crank back at the axis of "rotation" is not the correct approach.

By the time you have the gearing ratio to lift 680kg, upon release it'll spin at "a million" RPM killing someone.