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!

 

[Gopalakrishnan C]

What if i am adding counter weight to match COG and COR?

 

[VEBill]

Then you'll have the opposite problem when the 'Unit Under Test' (UUT) is removed from the fixture.

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You should be able to design a cradling fixture that can be attached to the UUT, to allow it to be lifted from its cart. The lifting is by winch, with due concern for all possible failure modes. Redundant support must be provided, at ALL times.

The axis of rotation would be through the CoG, allowing effortless rotation. That way you actually could use a little hand crank to perform the rotation. BECAUSE the lifting force has been dealt with separately, by the winch.

The above suggestion does not constitute Engineering advice. You really should find someone to assist you with this. 680kg is more than sufficient to crush your coworkers.

 

[Gopalakrishnan C]

we have proven this design with electrical motor and Hydraulic jacks
But now we decided to increase overhanging distance and also wanted to move from electric and Hydraulic to Manual

so i decided to go for Screw jacks for lifting and Gear drive for hand crank

the whole structure looks like Frame welding fixture but we are using this tool for assembly also. Hence we need to rotate and position accurately

And still i did not find the Correct Torque calculation for offset/overhanging load!

 

[rb1957]

do you mean T = F*d ?

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

 

[SAITAETGrad]

Gopalakrishnan -

Thanks for the clarification.

Agriculture uses hand winches like these to lift grain augers.

From memory, once you get that type of crank moving, it is turning at a rate of approximately 180-240 RPM.

Most augers these days come with hydraulic lifts and wheel drives to make handling easier.

I think this is an application niche similar to yours.

 

[Gopalakrishnan C]

rb1957

Torque = Force X Distance is the basic formula.
But i do want to calculate the torque for over hanging load with COG eccentric to Center of rotation!

 

[Gopalakrishnan C]

@ SAITAETGrad

I have confined space for the assembly, i would like to hear you idea about

https://www.haacon.com/pageflip/hci/mobile/index.html#p=112

 

[rb1957]

why wouldn't the torque due to the weight about the axis of rotation be W*d ?

This is the static torque you have to apply to the structure to stop it rotating (it wants the CoM to align with the CoR).

Then you have to apply additional toque to get the thing to rotate, that'd be I*alpha.
There is also the option of looking at the problem from an energy perspective (as you've lifting the CoM).

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

 

[SAITAETGrad]

Gopalakrishnan -

Looks like a good option on the face of it. But I can't determine if this meets your regulatory and design requirements.

 

[MarkAF]

Hopefully you already considered this? Be very careful of the possibility of back-driving the mechanism. If the drive mechanism is not somehow self-locking, letting go of the hand crank will allow it to spin freely, and break somebody's arm.
I don't know this particular product at all; presumably this is what the catalog page described as "internal self-actuating load brake."