How were shay trucks able to climb hills better then regular steam engines of the time?
How did the ring and pinon gears help this?
On Shay locomotives the whole weight of the loco was available for adhesion, that is, all wheels were driven. Also they usually had a three cylinder engine and this, together with the reduction gearing in the drive to the trucks gave a much smoother drive to the wheels when compared to a conventional rod drive locomotive.
Malc.
…And beyond the gear reduction of ring and pinion drive was the small drive wheels making the ratio even more favorable to reduction for great power. Speed of these engines was not their ace in the hole…
The flexibility of the Shay truck insured that all wheels were at maximum contact witht the rail.
dd
What they said…
Speed wasn’t a consideration, pulling power was. With geared locos, Shays, Hieslers, Climaxs, and Dunkirks used 2 or 3 cylinders driving 8 or 12 (3 truck geared engines) via a direct driveshaft ment a tremendous amount of pulling power was available, also the weight of the locomotive being entirely on the rails gave them a much higher adhesion on steel rails allowing them to climb very steep grades, up to 10% while still pulling loads. Rod engines would tend to stall out before they would slide, rod engines are least efficient at starting or very low speeds and most efficient at road speeds where geared engines didnt suffer from this problem, the disadvantage to a geared loco was that its top speed was severly limited, often no more than 15-20mph.
If you’ve never seen one at speed, imagine this…your standing at a bend where you cannot see down the tracks. You can hear what sounds like the 20th century linited pounding at 80mph roaring up the valley, you wait, and wait …then you see it coming around the bend, smoke blasting out of the stack like a volcano, sounding with all the fury of an express train 30minutes late…only its barely going faster that a guy on a bike! As it passes you, you can see the pistons furiously whirling, the driveshafts spinning like some crazed corkscrew, and the wheels slowely chugging along…
one nice thing about a Shay - is that if the rails were wet, the brakeman could always WALK ahead of the train and sand the rails. His only problem was waiting around in the rain until the engine caught up with him[;)].
dd
This feature was a key selling point for all of the geared locomotives when addressing one of their key markets - lumbering. The rails laid into the woods were the railroad version of a rutted and potholed cowpath. The ties were often logs cut on the spot, and the roadbed was only minimally prepared, if at all. Rod locomotives, with their relatively long and stiff wheelbase, could not negotiate the undulating and very curvy track very well, if at all.
I recall a picture of a Shay negotiating track laid directly across a streambed…
Before the Uintah RR got larger power, they used some narrow gauge Shays. For a couple of years, they were having trouble with a large, very slow moving landslide. Every day, the MOW crew would relay the rails over this landslide, because they had shifted downhill overnight. They had a rail mounted steam shovel to level the ground as much as possible before relaying the rail. Then they would move the inbound and outbound trains over the bad spot. And start over again the next day. The flexibility of the Shay was really helpful.
They eventually found the underground spring that caused the slide and was able to stabili***he hill before purchasing their famous Mallet narrow gauge locomotives.
dd
ps - I know that their Mallets were not compound - but simple expansion - but if they called them Mallets, who am I to argue!