It’s easy to see all the parts of a bit by laying the mouthpiece across your outstretched fingers and letting the bit hang. This is also a nice way to see how the bit is balanced. The butt of the mouthpiece is where the mouthpiece attaches to the shanks. This is also the point of balance in a bit.
The cheek pieces (commonly called shanks and shown here with a red line) on each side of the bit extend from the bridle rings, where the headstall is attached, to the rein rings, where the reins are attached. More accurately the shanks (shown here with a white line) are the parts of the cheek pieces extending from the butt of the mouthpiece to the rein rings.
The purchases are the part of the cheek pieces on each side of the bit that extend from the butt of the mouthpiece to the tops of the bridle rings (shown here in green).
Whenever the reins are pulled the bit revolves around the butt of the mouthpiece. As the reins are pulled the rotation of the mouthpiece causes the bridle rings to move forward of the point of rotation and the shanks to move behind the point of rotation. This movement in turn causes the curb to be tightened on the chin and the crown piece of the headstall to put pressure on the horse’s poll.
We’ll continue next week with the effect the relationship between the length of the purchase and the length of the shank have on the leverage of a bit. It’s always important to remember that the biggest affect from any bit is the hands holding the reins.
For more information on Dennis Moreland bits call 817-312-5305 or visit: http://www.dmtack.com/pcategory/horse-bits/