puts her head down when galloping

Question
iv been riding my 16.1 shire x cob she ridden in straight bar pellem wth curb chain on single rein did ride wth double reins most time shes great other times she drops her head and very strong to stop shes not nasty or anything like that just wont stop when ask her to its strain my back any advice pls

Answer
    Hi Helen,
  Firstly, I would have to say that using a Pelham,actually encourages a horse to put its head down.
  Could I ask why you chose that type of bit? You say that you are only using one rein at the moment. Is it attached to the upper or lower ring? Galloping with the head carried too low could be dangerous, as she would not be properly balanced. Is that the only gait at which she does it? In training, at the trot, having them drop their heads is actually an advantage, as it builds up the muscles in the topline. When you want to raise the head, you don't do it by pulling on the reins, but by riding them forward into the bit, thereby causing them to lower their quarters (rather like a see-saw#, so the question of how she responds to your leg also arises.
  There may also be another issue at play here. Basically a horse #until it is trained) will "fight" pressure, with pressure. When a rider applies any kind of pressure to a horse, that pressure has to remain, as long as the animal ignores it, or fights against it. However, as soon as he/she shows any tendency to yield, the pressure has to be released immediately.It is only through the release that they learn. I just wonder if her reluctance to stop, could be related to this issue.
  Could you try a different bit, and perhaps, refrain from galloping for a while?
  Please let me know your thoughts on what I have said, and if you could answer the questions I asked, I might be able to "fine tune" my answer somewhat.
  Meanwhile I wish you luck,
         Slan,
         Brendan