Some think the horse was an ambler (like a Tennessee Walking Horse), but no facts exist to prove that. His conformation does seem to resemble the Plantation Horse, which had an ambling gait. - This was the best information I could find. Here is the link that I used. http://www.equinenet.org/heroes/travelle.html
Improved Answer:
Traveller was an American Saddlebred, at a height of 16 hands, 1,000 pounds, and a striking iron grey color with black points.
-Bratterratt-
Traveller was an American Saddlebred.
Quarter Horse, chestnut
A lady named Ruby.
No a Piston is not a breed of horse.
Traveler
Andalusian horse named Traveler
The breed of horse is a Thoroughbred, it is the horse that the cars are named after.
a yealand pony or horse is a breed of horse
The largest breed of horse tends to be the percheron but other large horse breeds are drum horse, shire, clydesdale, Friesian, or really any draft breed.
traveler
Traveler
Traveller.
Andalusian horse named Traveler