According to wikipedia the reaso they didn't go further than Hadfield was they had low gearing and on the section beyond Hadfield they would overheat and burn the traction motors out.
Yes i read that as well. Still puzzling though, from Hadfield, it's only 4 miles at 1 in 117 to Crowden or 6 miles to Woodhead at 1 in 117. Surely the motors can tolerate full power for six or eight minutes. Low gears from a standing start, have better acceleration on uphill grades.
oh and Merry Xmas all !!!