Talk:South African Class GF 4-6-2+2-6-4

Factor of adhesion
Contents of an email with comment received from J. Stuart Grossert:

From: "J. Stuart Grossert" Sent: Monday, August 11, 2014 1:46 AM To: "Kol Andre H Kritzinger" Subject: Re: [sar-L] 1927: SAR Class GF 4-6-2+2-6-4

Hi Andre:

Thanks again for your efforts. If I may make a comment on the GF information, you quote AE Durrant as saying:

"Considering that the Class GF was a fairly light and large wheeled locomotive that was more suited to passenger work than heavy hauling, a surprising number of them were sold into mining service upon retirement"

I should not be disagreeing with so prominent an authority as Durrant, especially as he is no longer with us to defend himself, yet I think this statement is not quite right.

The GF, fully loaded has a total mass very similar to a 19D, a slightly heavier axle load and a slightly higher tractive effort. However, the Garratt has its tractive effort spread over two engines and 12 drivers, thus its factor of adhesion is much better than a 19D, which indeed is rather slippery. Thus, I see a GF as being a very suitable loco for moderate loads, noting of course the Garratt disadvantage that its mass decreases as the coal and water are used up.

Certainly, the GFs were very successful on the Greytown and Kokstad branches, which are some of the most difficult routes on the old SAR with sharp curves and very steep grades. Also it was often misty, wet or, in the winter, icy.

Maybe you would consider removing the above sentence.

Best regards, Stuart

HALIFAX, NS, Canada   B3H 3X9