lbs/ft force value to turn powr loc drive shafts?

RoyTheBoy · #1 (**permalink**) 03-28-2010, 03:38 AM

Hi Guys,
I have been looking around the forum for some specs on the Jag powr-loc and de-rating. I have found a bit of info - but no one seems to know what the actual lbs/ft force (to turn one shaft against the other) is for a de-rated LSD. Rather that the 50% figure that is quoted in many of the posts I am looking for the actual force required to turn one input shaft whilst the other is locked. For example, the manual states that the force to turn one shaft whilst to other is fixed should be between 40 to 70 lbs/ft.

So, does anyone know what the force is AFTER de-rating? I have manged to get mine down to 38 lbs/ft by re-arranging the disc/plates. I am looking for some idea as to whether this will be enough.

Cheers,

Roy

jon@harrison.ne · #2 (**permalink**) 03-28-2010, 01:39 PM

If you are talking about the torque to turn the shaft and not the force, then the units are Lb ft (force x distance). In engineering school we had a saying: "it's one thing to get the wrong answer to a problem but at least get the units right".

RoyTheBoy · #3 (**permalink**) 03-28-2010, 05:10 PM

Quote:

Originally Posted by jon@harrison.ne

If you are talking about the torque to turn the shaft and not the force, then the units are Lb ft (force x distance). In engineering school we had a saying: "it's one thing to get the wrong answer to a problem but at least get the units right".

Jon

Thanks for engineering lesson.

BUT, can you answer my question?

What torque value (yes... in lbs/ft!) should you expect to read, when turning one output shaft (whilst the other is locked) in a Jag powr loc that has been "re-rated" to be less aggressive?

Roy

jon@harrison.ne · #4 (**permalink**) 03-29-2010, 11:06 AM

No I can't. Again-torque is ft lbs, not lbs/ft.

RoyTheBoy · #5 (**permalink**) 03-29-2010, 03:08 PM

Quote:

Originally Posted by jon@harrison.ne

no i can't. Again-torque is ft lbs, not lbs/ft.

game over!

David Hodgson · #6 (**permalink**) 03-29-2010, 03:14 PM

QUOTE=jon@harrison.ne; If you are talking about the torque to turn the shaft and not the force, then the units are Lb ft (force x distance). In engineering school we had a saying: "it's one thing to get the wrong answer to a problem but at least get the units right".

QUOTE=jon@harrison.ne; No I can't. Again-torque is ft lbs, not lbs/ft.

Hey jon, In integrity school we also have a saying: "Be consistent"

Merv and Sharon · #7 (**permalink**) 03-29-2010, 03:16 PM

http://en.wikipedia.org/wiki/Pound-foot_(torque)

http://en.wikipedia.org/wiki/Foot_pound

You have your choices, but no answer to your actual question Roy!

jon@harrison.ne · #8 (**permalink**) 03-29-2010, 04:15 PM

For the same reason that 2x3 = 3x2, the order of the units is immaterial, contrary to what someone said on another post . I'm not sure what this has to do with a lack of integrity. In the literature torque is expressed about an equal number of times in lb ft or ft lb. No need to bring in metric units until we get past this. I guess I am trying to do my small part to educate the public about some pretty basic engineering terms. Power (eg. Btu/min ) is constantly interchanged with energy (Btu). Recently Newsweek did a story on a Japanese solar power station and totally mixed up the units for power and energy to the point I couldn't figure out what the thing was capable of. I wrote a letter.

David Hodgson · #9 (**permalink**) 03-29-2010, 04:39 PM

My appologies jon, I see now you had an issue with the / symbol denoting division of the equation.

jon@harrison.ne · #10 (**permalink**) 03-29-2010, 04:50 PM

I appreciate your reply David. I was afraid this would go on for a while.

RoyTheBoy · #11 (**permalink**) 03-29-2010, 05:10 PM

Quote:

Originally Posted by Merv and Sharon

http://en.wikipedia.org/wiki/Pound-foot_(torque)

http://en.wikipedia.org/wiki/Foot_pound

You have your choices, but no answer to your actual question Roy!

Thanks Merv.

I'm SO over it now

. Jon has kindly corrected all of us so "Here endeth the Lesson"!

I am closing this off and moving the question over to the Cobra Club forum in the UK.

*Cobber* · #12 (**permalink**) 03-29-2010, 05:25 PM

I see this so much on this forum too.......

Don't worry about the diff you want two black lines not one.
I'm running a powerlock at original spec and have had no problems. On a tight slow turn over gravel you can here one side or the other slipping over the top of the loose gravel. On the road it's no problem and the diff allows enough slip.

RoyTheBoy · #13 (**permalink**) 03-29-2010, 05:29 PM

Quote:

Originally Posted by *Cobber*

I see this so much on this forum too.......

Don't worry about the diff you want two black lines not one.
I'm running a powerlock at original spec and have had no problems. On a tight slow turn over gravel you can here one side or the other slipping over the top of the loose gravel. On the road it's no problem and the diff allows enough slip.

Thanks Cobber,

This is what I needed to hear. "Real world" experience.

Cheers

Roy