Better than Shays? (other geared locos)

[Gumboots]

I was looking around and it last night and learned some stuff I didn't know. Not only were Shays not the only type of geared locomotive, but it appears they weren't even the best type. Shays just happened to be the most common, but some of the others had distinct advantages over Shays.

Shays could apparently derail easily, since the sliding joints in the driveshafts could lock up sometimes and prevent the trucks following the rails properly around curves. The other types of geared locos didn't suffer from this problem, since they had the driveshafts on the centreline and therefore didn't need sliding joints (a basic universal was used). The driveshaft and gear housings on Shays were also somewhat vulnerable to damage, being out at the side, while the other types had the mechanisms under the loco. There were other factors too, due to Lima continuing to build a design with outdated features such as boilers being bolted together instead of welded, and a general difficulty of maintenance.

The Heisler locomotive looks particularly good. It has a very simple crank with only one crankpin, and uses basic coupling bars instead of extra bevel gears to drive the second axle on each truck. The 90 degree V-twin arrangement of the cylinders would give automatic quartering of the drive on only one crankpin. A 90 degree V-twin has also perfect primary balance and decent secondary balance, which is why it has long been used in Ducati and Moto Guzzi motorcycles, so vibration should have been minimal. Heislers were apparently the fastest of the geared locos, but still had excellent low speed hauling power.

Links, for anyone who wants to know more:

http://www.steamlocomotive.com/geared/

http://www.american-rails.com/geared-steam.html

http://www.american-rails.com/logging-railroads.html

http://www.gearedsteam.com/shay/shay.htm

http://www.gearedsteam.com/climax/climax.htm

http://gearedsteam.com/heisler/heisler.htm

http://www.american-rails.com/heisler.html

http://gearedsteam.com/willamette/willamette.htm

[Hawk]

Moved to a more appropriate forum.

[Lone Cat]

And Mallets are downplayed. despite being invented in quite a same time. and Mallets are also favorite logging engines.

[Gumboots]

Yes, but they aren't suitable for very steep grades. The geared locos will go up tracks that will stop a Mallet dead.

[Lone Cat]

Even so by the 1920s. Mallets (and Garratts) became preferred mountaineer engines. Geared locomotive developments ceased with the introduction of simplified Mallets (and logging industry also uses Mallets in some significant quantities)