F3 Disassembly

Pulling an F3 apart is relatively simple, just take your time, and if something does not come easily, you missed a step. The first section is for the body, and after this section, there is one for pulling apart a motor block.

Removing the chassis from the body:

I have one of those adjustable cradles lined with foam. I throw a small towel over it to catch any grease, rather than have the grease get into the foam. This also keeps you from damaging the grills.

Lay the engine on it's back as shown below. Be careful not to damage the details on the top of the loco, or press on the grills.


Remove the 2 screws that hold the fuel tank on, one at each end, and remove it. It can only go back on one way, so don't worry. The screws are small, keep them with the tank. Don't mix them up with others, or you will strip the holes. they have pointed ends and are 0.106 over the threads and overall length 0.387"

The picture below shows the fuel tank and the screw near the front of the loco. You can see the locating pin that aligns the fuel tank also.

The picture below shows the screw on the other side of the fuel tank, nearer to the back of the loco and it's locating pin:

After removing the fuel tank, you will have revealed 4 more screw holes in the chassis, see the picture below:

You can now remove all the screws that hold the chassis to the shell.  

These screws are in deep, having a magenetized screwdriver helps, that way you are sure they are all the way out.  It may help to remove the coupler pedestals, this allows the trucks to swivel more. Make sure you have a screwdriver that fits them snugly. Don't try to remove the screws, especially the first time, with an ill-fitting screwdriver, if you round out the screwheads while in the loco, you will kick yourself.

There will be 9 screws on an A unit, 10 screws on a B. Remove them all.Note: these screws are 0.1" over the threads, 0.532" overall length, and head diameter 0.162. Why is this important? Putting in the wrong screws can strip the hole, slip through the shell (means won't hold the shell on), or crack the threaded posts. These screws have a flat end with a self-tapping notch. Very distinctive.

First, remove the 4 screws that were under the fuel tank as shown in the picture above.

The picture below shows where screws 5 and 6 are, by the rear truck: (the other one is on the other side of the body, rotate the rear truck to get to it)

The picture below shows the location of 2 more screws, numbers 7 and 8. Again, rotate the trucks to get to the screw on the other side of the body, Note the location of the switches.


Now, if you have a "B" unit, the last 2 screws are under the front end of the truck, near the sides of  the body like all the other screw. If you have an "A" unit, there is just one more screw, in the front center as shown below:

It's right behind the coupler pedestal. In many cases, to rotate the front truck enough, you may want to remove the front coupler pedestal to let the truck rotate more fully. Note: like all the others, the coupler pedestal mounting screws are unique, with a "washer head", the threads are 0.118" overall, and overall length is 0.335". These screws are also used to mount smoke units I think.

Now hold on! Before you try to pull the chassis out, you need to clear the brake hoses that are on the corners of the loco.

The end of the A unit, and both ends of the B unit have a small assembly of 4 black plastic brake hoses. Looking carefully from the bottom, you can see a pin from each of these assemblies protrudes through the body shell, and is basically in the way of pulling out the chassis/bottom plate. Use a flat head screwdriver, and push the little black tips flush with the inside of the body shell, or pop them off completely. (you can also trim them flush with an x-acto, but then you should glue them in place.

OK, now, stick your finger in the hole in the center of the bottom plate, and pull the unit out. If it does not seem to come, be sure you loosened all the screws until they "clicked" (reached the end of the threads), and moved the tips of the brake hose assemblies out of the way. If everything is free, it will come easily, but it's heavy! If it does not come, you did not loosen one or more screws completely.

Now is the time to re-glue the loose windows. If they are all in place, then push lightly on each one, and re-glue the ones that pop off (they will later!). You can also check any doors that do not swing freely or the springs have slipped so that they do not close. Look carefully at the doors, usually you can slide the plastic piece that serves as the hinge out of the body, and put the spring back in place, and slide back in. Be careful, this piece slides in a very thin dovetail groove in the body shell. I used the thin watery plastic glue. Don't get it on the visible part, or it will cloud up.

Put it back together in reverse order. A tip: take all 9 or 10 screws out of the bottom plate before re-assembling. Otherwise they can protrude from the posts where they engage the body shell. These posts have a recess on the end that mates to the body shell, if the screw is protruding, it can interfere with seating properly.

If the bottom plate does not go all the way "into" the shell, or a screw does not seem to tighten or engage properly, then it is usually a problem with alignment, the chassis is not sitting all the way into the shell. Repeat, if the chassis does not seat easily and evenly into the body, reposition it.

Truck disassembly

To take the trucks apart, remove the larger 6 screws on the bottom plate. They are shown in the picture below (Don't remove the 2 smaller screws that are in line with the sliders.)

 Now CAREFULLY lift off the bottom cover of the motor block. I say CAREFULLY so that you can observe the proper relationship of the parts inside:

Notice the brass bushings between the wheels and the gears. They are square, and they fit into recesses in the motor block, and the edges of these bushings are parallel with the cover (completely opposite to the 3 axle trucks). This is VERY important. Repeat, put them back in wrong and you trash the gears.

You can also see the power pickup wires that ride on the top of the axles. It is important they never get pinched under the brass bushings, but ride on the silver part of the axles.

To remove wheelsets, spread the sideframe on one side to get the axle out of the bearing, as in the picture below:

Next repeat for the other side.

IMPORTANT: the bearing in the sideframe takes the weight of the loco, make sure it is greased well. Put grease or a very heavy oil in these bearings when reassembling. I prefer grease for assembly, as in the picture below. For maintenance, I use a heavy oil if I do not disassemble the truck.

It is helpful to understand that the motor block "floats" on the axles, and the brass bushings are only to set the relationship of the axle to the rest of the gears and take up thrust from the gears. The picture below illustrates that well, there is no connection between the motor block and the sideframes except through the ends of the axles:

Here is an important trick when reassembling: put a few screwdrivers under the motor block to hold it in place when re-attaching the cover. It's REALLY EASY to get the brass bushings in WRONG. This will cause you to tear up your gears really fast. The bushing tops should be parallel to the top cover, and they should be in their little square recesses.

Here's a picture of how I do it:

Make DOUBLE SURE you have everything lined up. When everything is in place the cover should snap back on with light pressure. If it does not, STOP! and look things over again. Common mistakes are trapping the power pickup wire under the brass bushing, the bushing not centered between the gear and the wheel in it's little recess, and of course not having the bushings parallel to the cover.

Remember, since there are no ball bearings, make sure everything is lubed well, and do periodic maintenance on these power units.



Weather Underground PWS KCACARLS78