GP9 Turning Radius

[MR536]

The GP7 and GP9 both have 6 axles that I know of...but before I buy into this model...what are the chances they will perform on an existing 18" turn? Has anyone had experiences with these models derailing?

[Len]

The GP7 and GP9 both have 6 axles that I know of...but before I buy into this model...what are the chances they will perform on an existing 18" turn? Has anyone had experiences with these models derailing?

Actually, the GP7 & GP9 (GP = General Purpose, aka "Geeps") had 4-axle trucks, the SD7 and SD9 (SD = Special Duty) were the 6-axle versions. The extra axles were to reduce the axle loading, or weight per axle, allowing them to operate on branch lines with less than optimal track, hence "Special Duty" locos.

All of the Geeps I own will negotiate 18in radius curves just fine.

Most of the SD's I've got, except one Proto, will also.

That one makes 18in radius left turns fine, but jumps the track on 18in right turns.  Nothing appears to be binding, the wheels are all in gauge, the trucks have the same swing both ways, but it just doesn't like those 18in right curves. So I keep it on the runs with 22in, or bigger, curves and it's happy. All my other SD's handle 18in curves with no problems.

Len

[Doneldon]

MR-

Those early GEEPS have been modeled since the 1950s and
they've all done just fine with 18" radius curves.
                                                                                 -- D

[jward]

i have a gp7. which is the same length as a gp9. i have no problems on 18r with it.

[rogertra]

For those modelling in tight spaces, any Geep is the perfect choice on 18" curves and in fact, along with 40 and 50 foot cars, looks waaaay better on 18" curves than large SD diesels and articulated steam or any steam larger than say a 2-8-2.  Large steam, SD diesels and longer than 50 foot freight cars all like kinda odd and toy like going around 18" curves.

[Len]

I basically agree with Roger, with one exception regarding articulated steamers. Mantua's 2-6-6-2 articulated, based on a logging loco that was originally designed for rough track with tight curves, handles 18in curves fine. And it doesn't look completely rediculous doing it.

One of these days I've got to dig the "Death Spiral" out, and see just how tight a curve it can handle.

Len

[MR536]

Many thanks to all of you...a GP9 is what I am now waiting for (coming in the US Mail)...oh BTW way Len, from a previous post I made...I received good advise on banking my curves especially those tight 18" #4 turnouts.  Your Pronto may not like right turns...but it could need raising up a bit.  Went into the kitchen and found an old spatula in the drawer.  I cut the blade off and then 1/4' wide pieces...they work great for inclines...hahaha...now the better half was wondering what happen to the spatula !  Ooops!

[Ken S.]

Until a couple of years ago, my mainline had 18in curves that were handled quite well by both big engines and passenger cars. It surprised me since some of my engines (Atlas U34CH and Athearn C44-9W)  and most if not all of my passenger cars were recommended for bigger curves. The upgrade to 22in curves did pay off when engines found their pulling power increased. My HHP-8 hauled a 6-car train around my layout with ease back in August when it used to strain with a 4-car train.

http://www.youtube.com/watch?v=mDGSGdRp5Zo - HHP-8 hauling 6 cars.