"hell for leather"

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Robert L. Chapman's New Dictionary of American Slang (Harper &
Row, 1987, ISBN 0-06-181157-2) says:  "hell-for-leather or hell-
bent-for-leather adv from late 1800s British  Rapidly and
energetically; =all out, flat out.  You're heading hell-for-leather
to a crack-up [origin unknown; perhaps related to British dialect
phrases go hell for ladder, hell falladerly, hell faleero, and
remaining mysterious even if so, although the leather would then
be a very probable case of folk etymology with a vague sense of the
leather involved in horse trappings.]"