Relationship of tender to locomotive

I have another question or two pertaining to the relationships between tenders and locomotives.

In most pictures I look at, it seems as though the locomotive cab is open to the rear, with the tender directly accessible behind it, as a separate car that is open on top. On passenger steam trains, are tenders most frequently open coal cars, or are they more often completely enclosed cars? How far back from the cab of the locomotive do they usually sit? It seems as though some pictures show the tender to be almost a part of the locomotive, it sits so snugly against it. Also, is it very uncommon to find a completely enclosed locomotive cab, one that is not open to the rear, and if so, how would the fireman access the tender on such a train?

For example, in one of the photos in the thread about accessing the locomotive from passenger cars, the "corridor" tender looks as though it is sitting almost flush with the locomotive, which does not seem to have an open-air rear to the cab, but an internal passage into the tender. I am wondering if this is one of the few such designs, or if there are any non-corridor tenders that are completely enclosed, and accessed from a doorway in the cab, rather than an open back end. Any thoughts would be appreciated.

I'll whittle this question down a bit. Can anyone give me an example of any locomotive whose cab is fully enclosed at the back, and whose connection to the tender would have to be by a doorway or some other interior corridor? There's a photo of a Hiawatha A-class in another thread, but I can't quite see how the locomotive and tenders are attached.

I believe the answer will be no,unless you consider oddballs like the SP cab-forward type.
this and any other examples will necessarily be oil burners: the reason that the open rear of the cab faces the open front of the tender, and the gap between is covered by articulating floor plates, is that the fireman must move hundreds of pounds of coal from the tender to the firebox while the engine is operating. For most of the steam age, this was done with a shovel, so the distance from the coal bunker to the firing hole needed to be less than a step or two. Even large modern engines with screw conveyors and power stokers would require continuous unhindered access to the machinery and the coal bunker by the fireman. coal especially wet, perhaps partially frozen coal does not slide down bunker walls reliably , so must be poked and raked over frequently.
Secondly there is the heat. the back head of the boilers and the mass of attached steam piping were rarely insulated, and commonly operated at 300-350 degrees, to say nothing of the radiant heat from the open fire door. enclosing the rear of the cab, particularly in the summer, would then make mechanical ventilation necessary.

Thanks a lot for this reply; good info.

A lot would depend on what conditions the engine would be operating under. In very cold climates like Canada, it was
not uncommon to see completey enclosed cabs. I have seen locomotives that had to operate in very cold climes with
small steam radiators on the cab walls. Locomotives with enclosed cabs would have access doors facing the tender in
order to get at the coal / and or use the long clinker hooks to tend the fire. From what i have seen most of the
enclosed cabs were on the large mainline engines from about the mid 30's on.
The reverse would be the case for locomotives that were built for very hot climates, the cabs were very open, mostly a
roof for sun and rain protection, many times with out any sliding windows.

trapper

In many cases, a tender would be drawn up as close as possible to the cab, taking into account the room needed for the the engine and tender to turn. On the largest locomotives, the gap between the cab wall and the tender tank would be just widfe enough for a person to walk through. This also gave the tender the greatest capacity for fuel and water. Another foot or so longer could hold more gallons of water and a few more pounds of coal, or a few more gallons of fuel oil.

I've seen Canadian locomotives with a completely enclosed cab and tender, connected with a diaphragm enclosure. Nice and toasty for those bad winters up there.

A number of Kenyan Garratts, including the Class 59, had completely enclosed cabs. Surprising in a way, as Kenya certainly isn't the coldest country in the world, although it can get chilly at the higher altitudes, especially Timboroa Summit at over 9,000 feet. However the relationship between cab and tender of a Garratt is different from that of a normal tender locomotive.

In Germany, most tenders are attached to the locomotive with special couple bars. One main couple bar and two reserve couple bars. The main couple bar does the full pull load, the reserve couple bars are smaller, but both can take the load, in the case the main bar fails... so the reserve bars aren't in load during the pull, but attached... it the main bar fails, the reserve bars take over the load immediately.

If somebody want's to see, I can attach pictures.

It was impossible to detach tender and locomotive easily, and usually was only done in shops for maintainance