Using Crowfoot Wrench with Torque Multiplier

[clbackus]

Hi,

I am trying to establish adequate torque on essentially a turnbuckle assembly which has two jaw fittings on either end. The nominal torque needed is around 1500-1800 ft-lbs, the nominal size on the threaded turnbuckle rod is 2.5". The issue is the space I have to work with and I cannot use a standard socket with this application. Therefore, I have found an appropriate crows wrench adapter (3-7/8" across flats) to engage the hex on the turnbuckle body. The turnbuckle is being used to essentially clamp down on two large saddles, one upper saddle which sets on the top of a large cylindrical payload and one lower saddle which is welded to the floor of our shipping container (see example image). What I am concerned with is using a manual torque multiplier with the crowfoot wrench, since normally you need a reaction bar for the multiplier. However, in this case with the crowfoot wrench, we need the multiplier wrench to turn, which would mean the multiplier body would need to move as you are torquing the drive. Is this feasible to do? Is it even possible for the operator to hold the multiplier? Two operators perhaps, with one applying the input torque? I considered a ratchet binder turnbuckle arrangement which has the ratchet arm built in, but the problem with that is I don't know how much torque is being applied (thus clamping load) and it's not nearly enough anyway. Other solutions? Thank you in advance for your assistance!

 

[3DDave]

Ten feet of steel pipe and a deep-sea fish pull scale can give a good control on the applied torque. Get some big guys or a come-along to provide the tangential load.

I'd have to see the exact multiplier wrench to have a better suggestion. Normally a crow's foot adds a multiplier to indicated torque, but that would be based on the measured applied torque, not the multiplied amount, so the correction here I think would be small.

 

[EdStainless]

People usually find some convenient piece of structural steel to brace the reaction bar against. I have even seen steel added just for this use.

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P.E. Metallurgy, consulting work welcomed

 

[clbackus]

Thanks for the suggestions 3ddave. The only issue I have with doing the grunt method or the come along method for applied torque, is I'd like for them to know what input torque they are applying to the connection. That's why I'd prefer a pre-set torque wrench with a multiplier. EdStainless - Normally with a multiplier, the multiplier housing does not need to rotate. But, because of the axis of rotation is at the crowfoot wrench hex centerline and not the socket drive centerline, there would be a small angle the multiplier housing (i.e. reaction bar) would need to move as the turnbuckle body is torqued. If one man person can hold the multiplier housing, that would be okay. Thus my original question. How about is this possible with any standard or non-standard multiplier wrench? If so, any recommendations on tools? Is there a multiplier mechanism hand tool out there that could do this job, as envisioned? Thanks to you both!

 

[clbackus]

Oh, sorry 3DDave, I forgot you mentioned the deep-sea fish pull scale for measuring the tangential load. I was thinking the accuracy on this might be questionable as you are pulling it, unless it measures maximum force output in a digital readout or something similar. But, no I think that could be a good idea otherwise.

 

[Tmoose]

Is the clamp to secure the part for shipping?
Or years of dynamic and thermal loading?

I'd modify the top clamp to accept a Cap screw of some type to replace the right hand clevis. This cap screw could be torqued directly.

I'd use the crows foot or a bar to prevent the turn buckle body from turning.

Is some kind of locking mechanism going to be required on the tightened turnbuckle etc ?

 

[clbackus]

Hi Tmoose,
It is for shipping the large object shown on the saddle. However, the base assembly shown in the picture where the bottom half of the saddle is welded to starts in a vertical position (i.e. upended). Prior to shipping at some point, the base assembly is downended, so the lower saddle and upper saddle (not shown in picture) and the bearing shelf shown to the right of the lower saddle in the picture are used to react the heavy weight of the payload (180 kips) that is attached to the saddles and eventually shipped. During this down-ending, I want to ensure enough clamping load is on the payload to ensure the saddle joint stays put. There will be a fairly hard durometer rubber (polyurethane) between the saddle radius and payload surface to take the small amount of compression needed to keep it fixed in place.

i like your idea of a cap screw. I'll have to seriously consider that. Since it's being shipped there will be road vibration, but I hadn't planned yet whether I will necessarily need a jam nut or something to keep the load locked in place. Probably not a bad idea to incorporate something, not sure yet what to do about that. Ideas are always much appreciated.

 

[Tmoose]

I would plan on install installing wedges or blocking or some other mechanical stops to prevent or at least limit axial motion.