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Hydraulic Torque Wrenching

Hydraulic Torque Wrenching

Hydraulic Torque Wrenching

Ladies and Gentlemen,

I am looking for someone with hydraulic torque ratchet wrench experience, when used in out of the ordinary applications.

I have a situation where aircraft structure mechanics are required to apply 300 foot pounds of torque to bolts and nuts in confined spaces and in very awkward positions.  The injury rate is high and the actual torque values achieved are questionable.

I have been investigating and experimenting with the use of hydraulic torque wrenches.  Most of the hydraulic torquing in industrial activities is accomplished up in the thousands of foot pound ranges, while the range I am looking at is in the lowest ranges for hydraulic wrenches.

I am experimenting with ½" square drive wrenches in the smallest units available, that are ratcheting tools in the 55 to 400 ft lb range.  In my applications I am required to use the torque wrenches with extensions which actually moves the wrench up and away from the nut and out of the direct path of the reaction force.  This brings me to the problem of containing the reaction forces and the torque in place.

The Sales Rep I am working with claims that the reaction force must be contained at the same plane as the nut and socket, e.g. with the wrench and reaction arm extended above the socket the wrench is forced out of alignment with its own reaction force.  This action renders the wrench useless in this type of application.

Frustrated with reaction forces,

RE: Hydraulic Torque Wrenching

Chiefmarty: In the assembly of aircraft turbine engines, often it is required to apply torque to various fasteners, in the range that is not practical for a "traditional" torque wrench, or are in relatively inaccessable areas, as you describe.  In these cases we use a torque multiplier that applies the torque, and the resultant reaction forces on the same plane as the fastener being tightened. Typically, this is by way of a tube within a tube.  For example, the fastener being tightened, the torque is transmitted as you expect, through a 1/2", 3/4" or 1" drive. The reaction force is transmitted through an outer tube, that mates to two pins on the torque wrench, and reacts against adjacent fasteners "in the hole".  There are many torque multipliers available, from 4:1 up to 11:1 made by Sweeney, Dynapac, and other manufacturers. Being purely mechanical and not hydraulic, advantage being that you use your traditional, calibrated torque wrench for the input, thus the ultimate output torque achieved, you have a high degree of confidence in.  
Hope this helps, and not oversimplified too much.  Let me know me if you would like some pictures of such torque multipliers and tooling.


RE: Hydraulic Torque Wrenching

There are also hex drive wrenches in the 60-600 ft/lb range that could be used in your application. The key in any hydraulic application is finding the reaction point that will give you leverage without putting the tool in a twist. The accuracy +/- 3% will outweigh the others by far.

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