North Yorkshire Moors Railway General Discussion

Given good rail conditions, Repton will drag 7 up the hill to Goathland in both directions. However, any reduction in adhesive ratio becomes a problem. In theory, you need 13,538 lbf darawbar pull to drag 7 full coaches up the 1 in 49 and 6,648 lbf for the loco, giving a required tractive effort of 20,186 lbf. That compares well with the quoted T.E of 25,130 lbf. The loco only has an adhesive weight of 42 tons, though, and that translates into needing a coefficient of adhesion of 21.4% to avoid slipping. Compare that to a Black 5 which works out at needing 18% to do the same job. On polished rails, whether wet or dry, you are OK but on rails which have not been used for a while, (i.e. since yesterday) you have no chance without sand to artificially improve the adhesion. Schools have the luxury of sands to all four driving wheels in forwards but they do get blocked and it does depend on exactly where on the rail it is deposited as to how effective it is. In reverse there are no steam sands and you are reliant on the tender gravity sands which, in my experience are fairly unreliable, easily getting blocked, even when they were working when you left shed.
Thos figures quoted are for the 1 in 49. However, @Ploughman tells me Greenend is actually 1 in 41 and Darnholme curve is 1 in 42/43, both for long enough to have the whole train on and these are the favourie spots to slip to a stand going southbound, along with Beckhole under the trees.