I’m new here. I am modeling the Simpson Timber company railroad. Both Steam and diesel era 1940-1960. I’m building 3 blue box Athearn SW7 switch engines into the prototypes.
I have the older metal side frames on the trucks and plan on getting Northwest Short Line wheel sets for them. I am also using a Kato motor with a custom motor mount that I bought on eBay that isolated it from the frame. I’m getting brass flywheels that fit the shaft and have the Athearn coupling socket in them. I’m wiring it up with a 9 pin decoder plug and LED lights with the addition of ditch lights front and rear. I already have the proper dual head light to match the prototype.
One is a SW900 with dynamic brakes and the other two are SW1200’s with dynamic brakes. I want to be able to couple them up in consist with DCC. This will require the frame to be isolated from track and motor power or isolation of the couplers so I don’t end up with a dead short when they are connected back to back.
I have seen where they have been converted to DCC but the frame is still connected to the left side rail via the metal tab on the trucks. This would mean that I would have to isolate the Kadee couplers as they are metal and attached to the metal frame. I have been thinking about removing the metal tab from the truck frame connection and wiring the trucks directly to the decoder plug with wires only.
Does anyone have any advice to offer on cutting off the metal tab on the trucks and letting the frame rest on the plastic part of the trucks? I know it will drop the thickness of the metal tab and I could replace that with a similar thickness of plastic. Would I be better off using the later trucks with plastic side frames? Any help would be appreciated. Thanks Jim Ford
You could use plastic Kadee couplers. What I have done is to file down the Athearn metal coupler mounting tab in order to mount a standard Kadee plastic coupler box. This requires drilling and tapping for a 2-56 screw.
Mark
Welcome! Since the Kadee coupler box is plastic, I think just using a plastic screw instead of a metal one would mean the coupler was isolated. You can get plastic screws at the local hobby shop or from Walthers. Otherwise, several companies make Kadee-compatible plastic couplers. Newer Athearn engines come with McHenry plastic couplers.
In all cases, you need to check the height of the coupler - it might end up being too low if you use the original Athearn coupler support. You might need an underset coupler.
Thanks for the ideas. I think that I might just file down the coupler mount and put in a Kadee plastic box and move it in a bit to have more metal to install the screw.
On another subject I think that I like the 1970 version of the metal side frames vs the later plastic side frames. Does anyone have experience with these different types? Pros and cons of each.
Some of the Kadee boxes can have some of the back end cut off to allow moving the mounting position further in.
The plastic side frames are more detailed, but the metal ones add more weight to the loco.
I think that the loco’s with the plastic side frames came with the updated motor.
Mark Vinski
I went to hoseeker.net and have figured out some things. The SW7 1966 version has metal side frames and the worm gear is enclosed in the main gearbox with a clip on top. It also has a cast headlight tower and no flywheels.
1970 of which I have has metal side frames and a worm gear enclosure that snaps on top. It has a metal headlight mount swagged on the front of the frame and gray flywheels. It comes with sintered iron wheels that can be replaced with Northwest Short Line wheel sets.
The next iteration of this from what I can gather is some time in the 1980’s this one has plastic side frames and internal axle bearings the worm gear still mounts the same but the power pickup is through the metal plates that mount the bearings. Another note is that on the later plastic side frames is the gold motor.
It seems that the gold motor mount area in the frame is a tad bit larger. I have some 3D printed motor mounts that I bought on eBay to install a Kato motor in the SW7 they fit the dummy locomotive frame with plastic side frames but not quite in the 1970 metal side frame gray motor. I found this interesting since the same part number is cast into both versions.
I like the metal side frames because they don’t fall off as easily as the plastic side frames. I modified my dummy locomotive frame to accept the Kato motor but will use the metal side frame trucks on it. A-line sells brass flywheels that fit the 2mm shaft on the Kato motor and uses the Athearn coupling socket which they also sell.
I already had 1 SW7 1970 Burlington Northern 127 and I bought 3 partly detailed shells with the proper dual head light already installed. They were also painted the right color for the prototypes that I am modeling. I also got a dummy locomotive chassis with plastic side frames in the lot.
I will be keeping an eye on eBay in search of 3 sets of metal side frame trucks and 2 of the later frames. I know I will have as much into these three locomotives as new ones cost but will have the joy of building them. One will be SW900 with dynamic brakes and two will be SW1200 with dynamic brakes. The number and placement of the louvers is also wrong so I will be fixing that.