What is this wrench for?

[Hal]

Got this in an auction lot. AB Sullivan Machinery Company. Based on the company history from Google, I suspect it’s for some type of air compressor, or other drilling or mining machinery.

 

[mike93lx]

Wild guess, but maybe that narrow end would be to turn a valve?

 

[cgrutt]

Believe I had an old router that used a pair of wrenches similar (but much smaller) to that for the collet. The thin end would index on a couple of flats cut into shaft and hold it in place.

 

[cvairwerks]

Might be a bonnet wrench.

 

[micromind]

The narrow end would fit a pretty fair number of ball valves.

 

[four.cycle]

"The firm had been founded in 1868 by J.P. Upham, Albert Ball, and Roger Love, to manufacture diamond drills (invented by Ball) and other quarrying machinery, water wheels, and mill fittings"

^ That part there tells me that they would have had the capacity in house to produce a double-open-end wrench without much difficulty.

726 shows up in an old Williams listing, but with different size openings than what you've got there, which is most likely a special-made piece intended for repairing a particular machine.