How many engines to pull a real RR car?

[Boyd]

My intent was for each 12" of movement of the O gauge engines there is 12" of movement of  the real RR car. No form of reduction. I see this as something to be done by a O gauge 3 rail train club or maybe even Lionel if they want some press.

[lionelsoni]

Using a lever or block and tackle, there is no limit to how heavy an object can be moved with how small a force.  As Archimedes said, "δῶς μοι πᾶ στῶ καὶ τὰν γᾶν κινάσω".  So even a Z-scale locomotive can move a prototype car that way.  Since that takes all the fun out of it, I think we need to make a rule that force-multiplying techniques may not be used.

[jwse30]

since we have a height issue to contend with anyhow, would throwing a block and tackle in the mix help reduce the number of engines needed (at the expense of increasing the travel of said engines)?

 

J White

 

[RockIsland52]

Fertile minds. 

Jack

[8ntruck]

Sounds like a plan.

When and where?

[lionelsoni]

I would space the tracks more like 3 inches and use more of them, like 32 tracks across 8 feet.  I would fasten each line to a postwar freight truck coupled to the rearmost locomotive and run it through a screweye at the end of its track., to insure that it stays perfectly straight.

There would have to be quite a few transformers.  Each one should power tracks spaced throughout the herd, so that a failure or tripping doesn't unbalance the force on the whippletree, and each transformer should power locomotives all of the same type, so that they can all be run close to their limit of adhesion, which can be measured by experiment transformer-by-transformer before the big pull.

[sir james I]

Also, you would have to lock the couplers closed. You would have to make some kind of harness to attach the engines with. You can't just tie a big rope to them.

[lionelsoni]

The model track doesn't have to be at the same height as the prototype track.  Just put it on a (very sturdy) table about 4 feet high, level with the prototype coupler.  Attach each locomotive group  to a point directly behind it on a whippletree mounted on the car's coupler.

Just in case it works, put a bumper between the car and the table.

[Boyd]

One sheet of plywood laid down between the rails. 2 feet average length of engine. Paralell tracks spaced 5 inches center rail to center rail=9 engines wide x 4=36 engines per sheet. So two sheets of plywood with tracks plus at least one more sheet for whatever length you want to pull the car. Now getting power to all of the engines would be a bit of a job. Lining up the track sections from one sheet of plywood to the next one would be a challenge. Run a rope to the back of the real RR car to lessen the angle. Now if all the engines were steam this really could put on a show. Pray that it does not rain.

[8ntruck]

CTT lists 'drawbar' pull in their locomotive reviews.  I think I remember seeing some with about 3 pounds.

Following this reasoning and building on Lionelsoni's numbers, we'd need 165/3 = 55 locomotives to pull a real freight car.

Hitch height would be a big problem, though.  The real rail car being much taller than the model locomotive means that as the locomotives pull, they would tend to be lifted off of the track.

[lionelsoni]

This is actually not that hard to figure out:  The rule of thumb is that moving a real car on level track takes about the same force as moving a frictionless car up a 1/4-percent grade.  If an empty car weighs about 33 tons, this would be about 66000/400 = 165 pounds.  To get that tractive effort using steel wheels on steel track (whether prototype or, in this case, model) requires about 4 times that weight on the drive wheels, or 660 pounds of toy locomotives, assuming all wheels are driven.  That's 33 pounds per locomotive, which seems a little high.

But, if we consider the possibility of using magnetraction or traction tires, it might just be possible.

[stebbycentral]

Something like this, you mean?

[overall]

Not sure on 027 engines. i think the german company marklin did that one time when they lashed up a number of their HO engines and pulled a car, or "wagon" as they call it over there, for a few feet.

George

[Boyd]

Say if a real RR car was sitting on a flat straight section of track with its brakes off, and then we laid about 100 feet of 027 track down between the rails, then 20 O gauge engines linked together and a rope going from the last engine to the RR car, would 20 engines move the full size RR car?