Treb′le-tree.
（Vehicle.) A whiffletree for three horses. An equalizer.
In Fig. 6637, the draft may be equally apportioned among the three horses if they are of equal energy and strength, but either of the outside horses may be favored by shifting the pivot-bolt of its double-tree.
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| Three-horse equalizer. |
In Fig. 6638, the third whiffletree is attached to a cord which runs around pulleys on the splinter-bar and tongue, and connects to the long end of the splinter-bar, to equalize the draft on its two ends.
