What is Ironwood?

[Rhodemont]

On my Meadowbrook cart we refer to it as the singletree as the swivel bar that the driving harness traces hook to.  It pivots on the cart and takes the entire load.  I broke mine once and had to order a singletree.  I am pretty sure it is ash.  As for logging a bit with my horses we always call the bar directly behind the horse the whippletree.  When pulling with two or three horses the next spreader out are cross bars.  Using these names prevents miscommunication on hitching to a log which can be a disaster if done wrong.  I am sure this is all regional and depends on who taught you. 

[SwampDonkey]

Old Scottish blood here called single yarding horse attachments swingle trees (single trees). I've not seen any horse logging book call it a whiffletree, although a single tree is considered a type of whiffletree. So 6 of one and half a dozen of the other. :D

[Al_Smith]

My experiance with horses is just Shetland ponies .Little knot heads .It's just a good thing they are small because they would be a chore to handle if they were as large as a draft  horse .

[JD Guy]

The  whippletree is the spreader bar that the horse work harness traces hook onto the ends.  In the center a hook for the logging chain to attach. 

Thanks All!