A picture is worth —
Lateral-box by Edmund, on Flickr
Of course the geometry of the driving axle is constrained by the side rods and a certain extent the brake shoes and hangers. Negotiating a curve of any appreciable excess will certainly have an effect on increased flange wear (some locomotives had flange lubricators) and tracking ability.
The modern diesel radial "steering" trucks allow the axle to remain somewhat perpendicular to the rail whereas the "coupled" steam locomotive can not offer the same "steering" ability even with added lateral motion.
A blow-up of the Franklin drawing:
Lateral-box_Franklin by Edmund, on Flickr
Good Luck, Ed
Well, it means lateral motion. The Alco devices are explicitly spring-centered, and 'floating' makes me think more of free lateral (depending on the hydrodynamics of the bearing lubricant to control the actual 'freedom' to bang between hub liners) rather than compliance. The special patent lateral motion devices are also expensive and require a certain amount of ongoing care and attention. In my opinion the most important place to have one is on the leading driver axle, to facilitate guiding into curves.
I was surprised to find that all four driving axles on a PRR T1 have free lateral by 1947. This only makes sense if there is very good positive location both by the front truck and the rear of the trailing truck.
I don't know what Southern used to 'float' drivers, and would like to know more exactly, by class if possible.
oldline1 Colorado Ray floating front drivers. Anyone tell me what that term means? I've never seen that applied to a steam engine. Could that mean Alco lateral motion devices? oldline1
Colorado Ray floating front drivers.
Anyone tell me what that term means? I've never seen that applied to a steam engine. Could that mean Alco lateral motion devices?
oldline1
Yes, lateral motion devices.
Sheldon
I'm in the dark on that as well. Hopefully someone will know the answer.
Ray
A 1949 Employee Timetable for the Asheville Division (today's S-line) lists weight restrictions for the following steam engines: Consolidations, Mikados, Santa Fes, Pacifics, and Mountains. Santa Fes and Mountains could only be operated if they had floating front drivers.
to the forum. Your initial posts are moderated, so I am bumping it so it will rise to the top and someone who might know the answer will have a better chance at seeing it.
Henry
COB Potomac & Northern
Shenandoah Valley
What Pasenger Locomotives were used on the Southern Railway S-Line between Asheville and salsburry?
I know the PS-4 went through asheville but dont know if they ever went on the s line