DUM-BEL Wrench

[Danks]

Looking for any information on manufacturer, Patent Date on this wrench that I obtained at a swap meet on Sunday.
Have seen smaller examples of this style, but this is the first one of this size.

[strik9]

I have a bunch of those with different names and metals used in making them.  Brass to the worst pot metal ever.   Post a pic of any lettering on it when you can an I will get back to this thread after work.   I have never found a big one myself.

[EVILDR235]

I recently picked up a Craftsman one that has rotating heads and is made of steel. SAE model that might work for a bicycle, but probably worthless for any other use. Showed it to the dog and he tried to pee on it.

EvilDr235

[Danks]

The only markings on the wrench are  DUM-BEL, PATENT as shown on the photograph:-

[amecks]

I have some of the bicycle wrench ones but I'd rather carry a 6" adjustable - takes up less space in a tool kit. 
I can't find it now but last night I saw a sold listing on eBay.UK which listed a "Dum-Bel" wrench (spelled as in quotes) and they used "Ford" also in the title.  It was an old listing from last June and no longer had a photo. And I forgot to pay attention as to selling price. 
If someone can find that listing perhaps the seller can provide more details.

[EVILDR235]

Pot metal tools are worthless. Maybe could be used on grandma's treadle Singer sewing machine.\

?

[strik9]

That comes closer to the Walsco US made ones I have.   

   Others are Eldi, Oxwall and Bronznor but are different styles.   The potmetal are quite worthless but the brass are nearly usable.   The chromed one is British and mostly usable. 

[mvwcnews]

The only U.S.  "dog bone" wrench patent I'm aware of is a design patent from 1919 (  http://www.datamp.org/patents/displayPatent.php?number=53597&typeCode=2 ) .  I've never seen one  this large -- I'm not counting the rotating socket head "dog bone" wrenches that some of the others have mentioned.