Truck bolsters and draft gear sizes....

[10KPete]

Mike, thanks for the information and photos! You've provided a great deal of illumination on this subject for me. The picture is really coming together now how all this hardware works.

Now I need to continue to chase down suppliers of 2 1/2" scale stuff!

Thanks again,
Pete

[rassel1986]

Hi,

It is interesting for me to know why do all existing friction draft gears at this moment have a twin steel spring inside? I'm talking only about the compression springs (not release springs). There is no-one friction draft gear with a single compression spring inside. The question is, why?

[ccvstmr]

There are multiple reasons for the two springs. 1) the springs (with accompanying hardware) are self-center. 2) one spring cushions the forces during coupling. The other spring cushions the forces during train starts.

In the few 1.5" scale sprung couplers that I have (loop shank couplers or similar)...I lean towards a stiffer spring. Want something close to a solid shank coupler, but still has limited cushion. Do not like the "slinky effect" that results from soft springs. Some coupler mfgrs use hard rubber inserts or similar. All for the same purposes as noted. Hope that helps you. Carl B.

[vernon911]

FYI for the 2.5" scale crowd,

We carry 2.5" scale angle valves. These valves are cored out to pass air but are not a fully functional valve.

www.precisionsteelcar.com

Regards
Paul

[rassel1986]

Thanks ccvstmr! I think there are many reasons why single spring draft gears are not using in railway at present. But i can not find the main reasons, i mean technical reasons.

[johnpenn74]

Springs In Draft:

The evolution of the draft gear brought us to the following 1) compression of the train is sprung and 2) tension of the train is rigid. This is the case for modern draft gear today, and most earlier stuff developed in that direction. You can find examples of where we spring in both directions. But largely gone now.

This double sprung version is done due to space limitations (two springs twice as much force. In reality it could spring in both directions, but the center sill behind the draft plates prevents its motion in that direction.

Earlier versions of draft used a bar running longitudinally down the axis of the coupler shank and a spring on the bar. (Similar to Harlocks application). However, most again only has the spring on one side to it would would be in rigid in tension.

Truth is, if you push hard enough in reverse on the compression side of the draft you will go rigid due to the striking plate head on the coupler. Some live steamer never take this into account when mounting the couplers on their cars. If you are totally compressing the draft spring when pushing the car then the coupler distance is too long.

JP

[makinsmoke]

Morning John,
Guess I'm confused. The loop shank coupler with
two springs provides compression in both forward and reverse movement. If you are speaking of the single spring coupler then I understand.

I am still mistyfied why everyone would not want sprung draft gear even in our scales.

If the reason is tearing up equipment then the springs are too light and/or the engineer has no respect for the equipment he is pulling nor the
wherewithal to do it correctly.

The much maligned aluminum couplers served this hobby for many decades because that is awe had, yet a complete breakdown of the hobby due to broken couplers simply did not happen.

My belief is it was because of the two things above, properly sprung couplers and reasonable
operation by the engineer.

Just my two cents.
Brian

[Pontiacguy1]

I think it was also the fact that back during the earlier days of the hobby most trains were pretty short. Now it isn't uncommon at all to see a train consisting of 10, 15, or more cars rolling down the track. Back when I was first around this hobby in the early 1980s, that was really uncommon. Most trains were only about 4 or 5 cars in length and were only carrying 3 or 4 passengers. I think the size of trains has grown a lot. Also, when you get a long train with a lot of sprung draft gear in it, you end up with a lot of slack action, which of course the prototype had to deal with too. I've found that I don't always want sprung draft gear in every car. What i've found that works good for me is to have about half, or slightly less than half, of the cars having sprung draft gear and the rest being rigid. That way, there is still some cushion in the train and some give to it, without the excessive slack action.

[ccvstmr]

Rassel...I have been on long trains. Played conductor for Quentin Breen back in 2002'ish...at the end of a 46 car train. I can tell you the slack action was wicked. Not only during train starts/stops...but when the train reached a "valley". The front of the train would slow down, while the back of the train was still descending the grade.

There's nothing wrong with sprung couplers...as long as people understand the application and limitations. Too many sprung couplers in a train and it might act like a "rolling slinky". Many hobby supplies still provide loop shank, double-spring couplers (or alternate cushioning material). I have several cars in the fleet with this type of coupler. I opted for the heaviest spring I could use. Why? I wanted to springs to absorb the impact from hard couplings while acting nearly solid during most other conditions. Have been most satisfied with this methodology. So this similar to what Pontiacguy1 described.

Solid shank couplers are drilled 1/64" over the size of the coupler pin. I'll add too...depending on the coupler mfgr, there's a lot of slack in the coupler jaws when two couplers are mated. So slack action in our hobby trains is not only in the draft gear (springs), there's also the actual coupling as well. Make sense? Carl B.

[Loco112]

On the 3' gauge, truck interchange was common, so if they are not exactlythe same bolster height, they must be close. The center plates changed in about 1930 when the flat center plates became standard. If you stick to 2.5" scale and model the prototype designs you should be able to use those as your standard.