Locomotive
Disassembly
This page covers complete disassembly of each A1G locomotive, model by model. The RSC-2, GP40, and SD45 are grouped together because the disassembly of these units is virtually identical. Since motor disassembly is covered on the respective pages, this discussion will be restricted to the removal of the motor from the chassis. I also recommend obtaining the original Atlas maintenance and repair manuals for these locomotives if possible.
Jump to: E8 C-Liner 0-8-0 RSC-2 GP40 Pacific WDT 0-6-0 SD45 Mikado 0-4-0 Cow & Calf
Remove the chassis from the shell by orienting the locomotive so the bottom is facing down away from you and you are looking at the top. It is best to be sitting down so the chassis can fall into your lap or have a soft surface available underneath to catch it if you drop it. Insert the fingernails of your two middle fingers of each hand between the fuel tank skirting on each side of the shell and the frame and rest your thumbs on the top of the shell. Pull outward on the skirting to disengage the four locks that hold the shell to the frame and shake the chassis out of the shell (sometimes it will just fall out). Be gentle with the skirting as the plastic here is thin and will break easily. Of course, if the frame is swollen from Zamac deterioration, it may be stuck and further measures are required. You may be able to insert some sort of tool into one of the two front portholes and try to push it out or just keep shaking it while hitting your knuckles on the underlying surface to try and jar the frame loose. You can also try to gently pry the chassis out by inserting toothpicks between the frame and skirting to keep the locks disengaged and then working with a flat bladed tool of some kind around the shell. Patience is the key and once you get it started, the chassis will come out.
Remove the front truck by inserting a suitable screwdriver through the hole in the phenolic contact plate at the bottom center of the truck and withdrawing the attaching screw from the frame. The hole is the more forward one of the two in the phenolic and you can see the slot of the screw head in there.
To further disassemble the front truck, remove the two screws holding the phenolic plate to the truck. If the truck is from later production with the auxilliary pickup shoes, they can also be removed at this time as they are held in place by the same two screws. After the screws are removed, they can merely be pulled out of their recesses in the truck. With the phenolic plate off, the wheels and axles can be removed by grasping each wheel with a tweezers or small pliers and pulling straight out. If sprung axles are used, be careful to not let the axles and springs fly away. The attaching screw can also be removed and there is a spring underneath it too so don't lose it. This is normally all the further the front truck has to be disassembled for maintenance or service. The two metal plates on the top of the truck are held to the plastic truck frame by the tops of the two phenolic plate mounting studs which are swaged over like rivets. It is possible to remove them by bending the swaged metal enough toward the center to allow the plates to be lifted off but it's usually not necessary to remove these. The only real reason would be if there is a problem with the sprung contact held captive by the rear plate.
The coupler is removed by bending the tabs of the retaining clip up straight, pulling the clip out, and removing the coupler and spring.
The rear truck is removed in one of two ways, depending on the vintage. The very early units have a snap ring or "E" clip around the groove at the end of the worm. You have to begin to push this off with some flat object like a screwdriver (I use a flat wood stick to avoid scatching anything if I slip) from the open end of the clip and then work the clip off little by little. It's a pain in the you know what! Also, keep one finger over the clip while you do this to keep it from flying away. But, regardless of any precaution, the clip is still liable to disappear. I speak from personal experience. There is also a very thin washer under the clip to keep track of too. After the clip is removed, the truck will just lift straight off the worm.
Later units are much easier. There is a copper keeper plate that slides into the groove on the worm and you merely loosen the screw located toward the front of the truck and slide the plate forward out of the groove. The truck then just lifts off.
With either style, further disassembly is by removing the single screw and sliding the black metal plate toward the rear and lifting it clear of the coupler. The coupler and spring, drive axles, idler gear, and idler axle can now be lifted out of the truck frame. The brass nut in a recess on the topside of the truck that the screw mates with may be loose and drop out so watch for this to avoid another loss.
The headlight bulb and socket are removed by prying the assembly out of the frame recess. The bulb unscrews from the socket. There is a dab of paint applied over the bulb and socket from the factory where the two meet to keep the bulb from loosening but won't interfere too much with purposeful removal.
Unsolder the lead wire from the lug at the hot motor brush holder, remove the screw retaining the contact plate at the front underside of the frame, and remove the two motor retaining screws. The contact plate and motor can now be removed, the contact plate from the bottom, guiding the lead wire through the frame opening, and motor from the top.
Remove the chassis from the shell by orienting the locomotive so the bottom is facing down away from you and you are looking at the top. It is best to be sitting down so the chassis can fall into your lap or have a soft surface available underneath to catch it if you drop it. Insert the fingernails of your two middle fingers of each hand between the fuel tank skirting on each side of the shell and the frame and rest your thumbs on the top of the shell. Pull outward on the skirting to disengage the four locks that hold the shell to the frame and shake the chassis out of the shell (sometimes it will just fall out). Of course, if the frame is swollen from Zamac deterioration, it may be stuck and further measures are required. You may be able to insert some sort of tool into one of the two round openings (steam generator stacks?) at the top rear of the shell and try to push it out or just keep shaking it while hitting your knuckles on the underlying surface to try and jar the frame loose. You can also try to gently pry the chassis out by inserting toothpicks between the frame and skirting to keep the locks disengaged and then working with a flat bladed tool of some kind around the shell. Patience is the key and once you get it started, the chassis will come out.
Remove the rear truck by inserting a suitable screwdriver through the hole in the phenolic contact plate at the bottom center of the truck and withdrawing the attaching screw from the frame. The hole is the more rearward one of the two in the phenolic and you can see the slot of the screw head in there.
To further disassemble the rear truck, remove the two screws holding the phenolic plate to the truck. If the truck is from later production with the auxilliary pickup shoes, they can also be removed at this time as they are held in place by the same two screws. After the screws are removed, they can merely be pulled out of their recesses in the truck. With the phenolic plate off, the wheels and axles can be removed by grasping each wheel with a tweezers or small pliers and pulling straight out. If sprung axles are used, be careful to not let the axles and springs fly away. The attaching screw can also be removed and there is a spring underneath it too so don't lose it. This is normally all the farther the rear truck has to be disassembled for maintenance or service. The two metal plates on the top of the truck are held to the plastic truck frame by the tops of the two phenolic plate mounting studs which are swaged over like rivets. It is possible to remove them by bending the swaged metal enough toward the center to allow the plates to be lifted off but it's usually not necessary to remove these. The only real reason would be if there is a problem with the sprung contact held captive by the front plate.
The coupler is removed by bending the tabs of the retaining clip up straight, pulling the clip out, and removing the coupler and spring.
The front truck is removed in one of two ways, depending on the vintage. The very early units have a snap ring or "E" clip around the groove at the end of the worm. You have to begin to push this off with some flat object like a screwdriver (I use a flat wood stick to avoid scatching anything if I slip) from the open end of the clip and then work the clip off little by little. It's a pain in the you know what! Also, keep one finger over the clip while you do this to keep it from flying away. But, regardless of any precaution, the clip is still liable to disappear. I speak from personal experience. There is also a very thin washer under the clip to keep track of too. After the clip is removed, the truck will just lift straight off the worm.
Later units are much easier. There is a copper keeper plate that slides into the groove on the worm and you merely loosen the screw located at the rear of the truck and slide the plate rearward out of the groove. The truck then just lifts off.
With either style, further disassembly is by removing the two screws that attach the black metal plate and lifting the plate away. The drive axles and idler gear can now be lifted out of the truck frame. The brass nuts in recesses on the topside of the truck that the screws mate with may be loose and drop out so watch for this to avoid another loss. The front coupler is removed the same way as the rear coupler.
The headlight bulb is removed by pushing the plastic block/contact out of its hole from the top of the chassis with a small screwdriver. The bulb will now drop out.
Unsolder the lead wire from the lug at the hot motor brush holder, remove the screw retaining the contact plate at the rear underside of the frame, and remove the two motor retaining screws. The contact plate and motor can now be removed, the contact plate from the bottom, guiding the lead wire through the frame opening, and motor from the top.
Locomotive
Remove the boiler shell by withdrawing the attaching screw located at the top of the shell between the steam dome and rear sandbox. Lift the shell straight up. Of course, if Zamacitis has set in, coaxing will be required.
Remove the screws that attach the eccentric rod cranks on each side of the locomotive and move the cranks out of the way. The main and side rods can now be removed. Keep the screws and the washers that go between the main and side rods where they won't get lost. Ideally, the different parts should be kept so they can be put back in their same relative positions (right side main rod back to the right side etc).
Lay the chassis upside down and remove the two bottom retainer plate screws and the retainer plate. The drivers, gear retainers and gears can now be lifted out of the frame. Note that there are washers on either side of the gears on the shaft that can drop off. Keep these parts in their relative positions too because they must go back from whence they came! Specifically, the two outer internal gears have 20 teeth and the center one has 22 teeth. The 1st driver pair has headed crankpins, 2nd driver pair has no crankpins, 3rd driver pair has threaded crankpins, and 4th driver pair has no crankpins. Thus, the 2nd and 4th driver sets could be interchanged and it wouldn't make any difference.The valve hanger/crosshead guide assemblies are riveted to the frame and normally would never have to be removed. They can be, however, by either bending the swaged end of the rivet enough to allow removal of the rivet or by drilling the swaged end away and then later reattaching with a similar rivet or appropriate screw and nut.
Unsolder the headlight bulb lead from the lug at the hot motor brush. The instructions that come with these locomotives state that you can push the bulb and socket out of the opening in the frame with this lead still attached but I have found that it is not really practical. Remove the two motor retaining screws and pull the motor straight back out of the frame.
Push the bulb socket and bulb forward out of the opening with an appropriate tool. The same socket and bulb are used as on the E8s.
Slide the cylinder and pilot beam assembly forward off the frame.
The frame should now be free of any other parts.
Tender
The tender shell is held to the tender floor by lateral locks similar to the diesel locomotives and is removed the same way by spreading the shell sides at the bottom.
Remove the trucks and axle wipers by withdrawing the attaching screws.
Remove the drawbar, spring contact, and washer by withdrawing its attaching screw.
The weights are riveted to the tender floor and again, would normally never have to be removed although they could be if necessary.
Remove the carbody shell by spreading the bottom sides of the body outward to disengage the two locks on each side. I do this by putting my thumb on the top of the long hood and using two fingers to pull out one side at a time. Be careful so your fingers don't slip and damage the handrail assemblies. They are relatively fragile and break easily. Sometimes it can be a real bearcat to get the shell off and sometimes it almost slips off by itself. On an easy one, it is possible to just merely pull down on the rear truck a little and the rear locks will disengage and then the front. On a difficult one, I cut away part of the tabs on the frame after the shell is off so that they aren't as long, making removal, the next time, easier. Remove the rear inside weight and the front inside weight (later RSC-2 units only).
Turn the chassis over and remove the screw near the center that holds either the plastic cover or the weight and remove the cover or weight. This will also release the motor from the frame. SD45s have a plastic cover that is removed by withdrawing the screw and then the weight is released by removing a brass nut from its mating piece in the frame.
Unsolder the wires attached to the lugs at the bottom of the motor. This will totally free the motor and it can now be lifted off the frame, withdrawing its half of the plastic coupling from the worm half.
On the front truck, straighten the wheel wiper tabs that are bent over the plastic separator (later units only) and remove the separator. Unsolder the wires (motor leads and headlight bulb leads) from the tabs. From the bottom, remove the screw and nut at the front center of the truck and remove the truck. On some units, you may have to remove the screw first, pull the truck down some, and then unsolder the wires from the bottom, depending on how far down the tabs the wires are attached.
At the rear truck, push the retaining pin out from one side to the other and remove. This pin is located just above the truck side frames and goes through the gear tower. Pull the rear truck downward and remove while guiding the wire leads through the openings in the frame (the wires are one piece with insulation removed near the center for attachment to the motor connections). The wires may now be unsoldered from the rear wheel wiper tabs or left as is if you prefer. The worm gear is now loose in the truck so remove it before you turn the truck upside down and it drops out (of course, I have never done this).
Remove the cover over the worm at the rear of the frame. The bosses that insert through the holes in the cover are extremely fragile and will easily break off unless you work the cover off very slowly and evenly at each boss location (of course, I have never done this either). The worm can now be lifted out of the gear tower. Sometimes it comes out easily and sometimes not so easily depending on how tightly the bushings fit into the recesses in the frame. You may have to use a small screwdriver and pry a little on the shaft at the rear. The frame should now be bare.
The trucks are disassembled by first holding the side frame and pushing the main frame down through the side frame. Then, pry the wheels off using a screwdriver between the wheels and truck frame. The wheel wipers can now be removed by pulling them out sideways. The two halves of the main frame will now separate by either pulling them apart or prying with a chisel-shaped knife blade at the center seam. This will release all the axles and gears of the rear truck and the axles of the front truck. Note how all the gears and axles are postioned in the rear truck before removing them. There is also a small flat spring that pushes down on the front axle of the rear truck that will now be free to get lost too.
The couplers are removed by bending the clip tabs straight and withdrawing the clip. The coupler and spring can now be removed from the truck side frame.
Locomotive
Remove the boiler shell by withdrawing the attaching screw located at the top of the shell in the steam dome. Pull the shell away from the frame a little at the front first and then work the rear part of the shell away from around the rear of the motor. The lower part of the bulkhead of the cab has a tendency to hang up on the motor cap. Also, keep the front of the boiler pointed down so that the headlight bulb doesn't drop out of its brass housing in the shell. Of course, if Zamacitis has set in, coaxing will be required.
Remove the screws that attach the eccentric rod cranks on each side of the locomotive and move the cranks out of the way. The main and side rods can now be removed. Keep the screws and the washers that go between the main and side rods where they won't get lost. Ideally, the different parts should be kept so they can be put back in their same relative positions (right side main rod back to the right side etc).
Lay the chassis upside down and remove the two bottom retainer plate screws, trailing truck, and pilot truck. Don't lose the pilot truck spring. The retainer plate will now lift off. The drivers, gear retainers and gears can now be lifted out of the frame. Note that there are washers on either side of the gears on the shaft that can drop off. Keep these parts in their relative positions too because they must go back from whence they came although, since the two internal gears are the same, it wouldn't make much difference if they are interchanged. The 1st driver pair has headed crankpins, the 2nd driver pair has threaded crankpins, and the 3rd driver pair has no crankpins.
Pull the hot headlight bulb contact and block out of its recess in the frame. Remove the two motor mounting screws and pull the motor straight back out of the frame with the headlight lead wire attached. This may be unsoldered from the lug on the hot motor brush holder if desired.
Remove the screw attaching the ground headlight bulb contact to the frame and remove the contact. This will also release the two valve hanger/crosshead guide assemblies which can be withdrawn rearward from the cylinder block assembly.
Remove the screw attaching the cylinder/pilot assemblies to the frame and remove these assemblies. The cylinder assembly is lifted straight up and this then releases the pilot assembly.
Remove the brass screw on the top of the frame that also receives the boiler attaching screw. This holds the worm housing to the frame and the housing may or may not now slide out easily. Usually, if the frame hasn't been affected by Zamacitis, it will easily come out. Otherwise you can try to push it out from inside the frame or leave it and do any worm cleaning with the housing in place.
The frame should now be free of any other parts.
Remove the headlight bulb and housing from the shell by withdrawing the retaining screw and sliding rearward. The bulb will just slip out of the housing.
Tender
The tender shell is held to the tender floor by lateral locks similar to the diesel locomotives and is removed the same way by spreading the shell sides at the bottom.
Remove the trucks and axle wipers by withdrawing the attaching screws.
Remove the drawbar, spring contact, and washer by withdrawing its attaching screw.
The weights are riveted to the tender floor and again, would normally never have to be removed although they could be if necessary.
Remove the carbody shell by squeezing in slightly on the black plastic sideframe near the center wheels to release the side locks and pull the shell straight up. Remove the weight.
Using a knife blade, pry the contacts attached to the ends of the motor brush holders away toward the outside to release the holders and remove the motor.
Remove the screw in the center, right behind the worm gear and the screw under the headlight bulb and lift the contact plate and sideframe off the Zamac frame. Oops, forget about the screw under the headlight bulb, it won't be there. This is something I added to my G.N version to keep the plastic contact plate down in the front so the wheel wipers stay in contact with the front wheels. I discuss this on the "Model Specific Issues" page.
Carefully pry the right side wheels off the axles and remove the spacers with them. I say carefully because the plastic Mehano used for the axles tends to be a bit fragile and is fairly easily broken. Now withdraw the axles and gears from the frame noting from where they came. The left side wheels may be removed from the axles if necessary by pulling them off.
The worm gear and side drive gear are removed from the frame by prying the side gear out and removing both gears. Again, be careful to not break these pieces.
To remove the couplers, straighten the clip tabs, withdraw the clips, and remove the couplers and springs.
The frame should now be free of other parts.
Remove the boiler and cab shell by using a knife blade to pry the shell out at the locks on the plastic underframe. Be very careful because the little strips of plastic on the shell underneath the locks break very easily. This is another of those personal experience things.
Using a knife blade, pry the contacts attached to the ends of the motor brush holders away toward the outside to release the holders and remove the motor.
Remove the screw in the center, right behind the worm gear and the screw in front of the weight "bump" (see, these already have a screw in the front) and lift the plastic contact plate/pilot step molding off.
Grasp the pins on the sides of the rear drivers that attach the main rods with a small needle nose pliers and pull them straight out. Remove the main rods.
Carefully pry the right side drivers off the axles and remove the spacers with them. I say carefully because the plastic Mehano used for the axles tends to be a bit fragile and is fairly easily broken. Now withdraw the axles and gears from the frame noting from where they came. The left side drivers may be removed from the axles if necessary by pulling them off.
The worm gear and side drive gear are removed from the frame by prying the side gear out and removing both gears. Again, be careful to not break these pieces.
To remove the couplers, straighten the clip tabs, withdraw the clips, and remove the couplers and springs.
The frame should now be free of other parts.
Locomotive
Remove the boiler shell by withdrawing the attaching screw located at the top of the shell in the steam dome. Pull the shell away from the frame a little at the front first and then work the rear part of the shell away from around the rear of the motor. The lower part of the bulkhead of the cab has a tendency to hang up on the motor cap. Also, keep the front of the boiler pointed down so that the headlight bulb doesn't drop out of its brass housing in the shell. Of course, if Zamacitis has set in, coaxing will be required.
Remove the screws that attach the eccentric rod cranks on each side of the locomotive and move the cranks out of the way. The main and side rods can now be removed. Keep the screws and the washers that go between the main and side rods where they won't get lost. Ideally, the different parts should be kept so they can be put back in their same relative positions (right side main rod back to the right side etc).
From the top of the chassis, remove the screw, washer, spring and pilot truck. This screw is located right below the hot headlight bulb contact.
Lay the chassis upside down and remove the two bottom retainer plate screws and trailing truck. The retainer plate will now lift off. The drivers, gear retainers and gears can now be lifted out of the frame. Note that there are washers on either side of the gears on the shaft that can drop off. Keep these parts in their relative positions too because they must go back from whence they came, particularly on the Mikado since different size gears and retainers are used in each location! Specifically, the front internal gear has 15 teeth, the middle internal gear has 18 teeth, and the rear internal gear has 23 teeth. The 1st driver pair has headed crankpins, the 2nd driver pair has no crankpins, the 3rd driver pair has threaded crankpins, and the 4th driver pair has no crankpins. Although operationally, it wouldn't matter if the 2nd and 4th pairs got interchanged, the 2nd pair has larger counterweights than the 4th pair. The shortest u-shaped gear retainer goes in the front slot , next shortest in the middle slot, and longest in the rear slot.
Pull the hot headlight bulb contact and block out of its recess in the frame. Remove the two motor mounting screws and pull the motor straight back out of the frame with the headlight lead wire attached. This may be unsoldered from the lug on the hot motor brush holder if desired.
Remove the screw attaching the cylinder/pilot assemblies to the frame and remove these assemblies. They must be slid forward to disengage from the crosshead guide extensions on the valve hanger/crosshead guide assemblies.
The valve hanger/crosshead guide assemblies are riveted to the frame and may usually be left in place. They can be removed, however, as on the 0-8-0s.
Remove the brass screw/nut on the top of the frame that also receives the boiler attaching screw. This holds the worm housing to the frame and the housing may or may not now slide out easily. Usually, if the frame hasn't been affected by Zamacitis, it will easily come out. Otherwise you can try to push it out from inside the frame or leave it and do any worm cleaning with the housing in place.
The frame should now be free of any other parts.
In my Mikado, the headlight bulb housing is held in place in the shell by a metal pin that won't come out, at least with normal effort. Whether they're all like this or whether some use screws, like the Pacific, I don't know. If there is a screw, removal is easy by withdrawing the retaining screw and sliding the housing rearward. This, however, is another part that normally wouldn't have to be removed for service of the mechanism. The bulb will just slip out of the housing.
Tender
The tender shell is held to the tender floor by lateral locks similar to the diesel locomotives and is removed the same way by spreading the shell sides at the bottom.
Remove the trucks and axle wipers by withdrawing the attaching screws.
Remove the drawbar, spring contact, and washer by withdrawing its attaching screw.
The weights are riveted to the tender floor and again, would normally never have to be removed although they could be if necessary.
Separate the locomotive from the tender by removing the screw on the loco side of the drawbar and pulling the drawbar down off the mounting boss. Be careful to not deform the two thin conductor strips on the top and bottom of the drawbar.
Locomotive
From the bottom, pull the lower (hot) motor brush holder out of its hole about 1 mm. This will allow the contact that is under it to clear in the next step.
Remove the screw that goes up through the center of the cylinder block and the retainer plate screw and plastic washer. The boiler and cab can now be removed by slightly sliding to the rear and swinging the front of the boiler down to clear the brush contact. Handle the frame by the pilot steps to keep parts from being pulled loose before you want them to be! The retainer plate is removed by unhooking the front from under the plastic driver frame. Other parts that will be loose at this time are the brush contact which can be lifted away from the frame, the worm gear which will either fall out or can be easily pulled out, and the front set of drivers which can be lifted out of the frame.
Remove the screws from the eccentric cranks and move them out of the way. Remove the main rods and rear drivers. The two small wheel wiper/contacts are removed from either side of the frame by pulling the two small brass pins out that hold them in position. Be sure to keep these two parts oriented left and right because they are not indentical.
Normally, this is the extent to which the chassis has to be disassembled for servicing or maintenance. The cylinder block is riveted to the plastic frame and the valve hanger/crosshead guide assemblies are attached to the cylinder block with pins. again, if absolutely necessary, the cylinder block can be removed as with other riveted assemblies and the valve hanger/crosshead guides by removing the attaching pins.
Remove the four motor mounting screws from the rear of the cab and pull motor out rearward to remove.
Tender
The shell merely pulls off from the frame. There are no locks holding it on.
Remove the drawbar and contacts by withdrawing the mounting screw from the frame.
Remove the rear truck and axle wiper by withdrawing the mounting screw from the frame.
Remove the front truck, axle wiper, contact, and contact carrier by withdrawing the mounting screw from the top mounted brass nut. The carrier is kind of a press-fit into the frame and may have to be gently pried out.
Remove the top brass nut and its insulating retainer by pulling the retainer up out of its recess.
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