Re: Military loads.
Daniel A. Mitchell
Your position is reasonable. I do have a loading diagram for the M-103 (or one of it’s look-alike predecessors) on a depressed-center 6-axle flat that appears identical to the Roco model.toggle quoted messageShow quoted text
I too have photos of the M-103 loaded on the standard Army 6-axle “Roco" flat. The weight of the tank (about 65 tons) is well within the car’s 100-ton capacity. Related issues are …
1) the M-103 Heavy Tank was substantially taller than it’s smaller cousin the M-48 Medium Tank. I suspect the issue may be overall height … in olden days with tighter clearance some movements may have required the lower overall height offered with transport on a depressed-center car.
2) For whatever reason the M-103 was often loaded on huge timbers running the length of the vehicle's track, between the track and flatcar deck. these were 8"-10” thick. This raised the height of the load by the same amount. Why? To spread weight? To reduce damage to the flatcar’s deck? Such timbers were often, but not always, used with the Army’s 6-axle “Roco” flat.
3) With the depressed-center car loading would be more of an issue. The tank is almost as long as the depressed center part of the car. Loading would almost have to be done with an overhead crane (common anyway). While turning the tank with a “neutral steer” (pivot) might have been possible, it would likely result in some huge stresses to the flatcar, and also tear-up the wooden deck.
In all cases, the tank is considerably wider than the flatcar’s deck (this is also true for the smaller M48-M60 tanks). The tracks overhang the edge of the deck by about a foot on either side. Side-clearance issues were a problem as the M-103’s Technical Manual clearly states.
Tie-down of such a vehicle in the “steam" era consisted of the use of MANY, large wooden blocks, cut-to fit, and jammed into several locations … in front and behind the tracks, and between the road wheels. Cleats along the inside-run of the tracks prevened side-to side shifting, possibly the use of large timbers under the tracks (above), and multiple (like 12-16) tie-down rods, chains or cables. Assorted loose items from the tank’s exterior (“pioneer tools”, machine guns), spare parts, etc. were packaged in wooden crates and strapped to the flatcar’s deck. Sometimes the main gun tube was removed and also packed in a wooden crate. Sometimes the whole load was tarped or partially crated.
Nowadays they seem to use mostly a spider-web of chains (6-8 on each end) and little or no blocking. The modern flatcars also have full-length tie-down channels set into the deck.