LAMRS Equipment, Periodic Locomotive Service

Model railroad locomotives are electro-mechanical machines that require periodic service. Unlike the prototype, this service is not required every day, but over periods of months to years or when something seems to have degraded.

Generally, periodic service will forestall the need to do remedial service for many years. The actual period of service is a subject of argument. Some model railroaders service their locos every few months, some only when they get around to it. I'm not at all sure what the "right" period is. Invasive service involving disassembly increases the risk of damage due to handling and perhaps reduces the risk of damage due to wear. Everybody has to work out their own "optimal" schedule.

The section below describes what usually needs to be done, roughly in the order of how often the specific service should be performed. Services performed most frequently are listed first. For issues related to the refurbishment of an older loco or the repair of a failed loco, see my Reliability page.

• Wheel Cleaning. Wheel cleaning is the service most often needed. The period of service will depend directly on the condition of a particular locomotive's wheels. New smooth and shiny wheels may not need cleaning at all, just the scrubbing action of the wheels on the track will keep them clean. Older locos with worn wheels may require cleaning hourly. If this is the case, it is best to sideline the loco or replace the wheels with new ones.

  Wheel contamination comes in two general forms, organics and oxides. The cleaning methods differ between the two.

  • Organic Contamination. Organic contamination is the black film that can be found on the track by rubbing a finger on the rail. This is the residue of oils, motor brush dust or airborne dust that finds it's way to the track. Once there is is "burnt" by passing locomotive wheels rolling over it and trying to draw current through or around the particle or film. What is left is mostly soot.

    This contamination is most easily cleaned off the wheels with an alcohol wipe. For a small scale locomotive, place a heavy duty paper towel (blue shop towel or Rags brand paper towel) on a section of track. Dampen the towel with rubbing alcohol and run the drives over it one truck at a time. Steamers may require being flipped over and cleaned with an alcohol soaked Q-Tip.

    Large scale locos are more tolerant to organic contamination, they probably do not require alcohol treatment. When they get oxidized enough to need cleaning, use an abrasive method as described in the next section.

    Old and worn wheels will scrape this stuff off the track much more efficiently that newer, smoother wheels and will need cleaning much more often.

    The cleaning period is variable, it is usually performed as a remedial action when the loco starts to stutter or even lose power pickup too often.

  • Oxide Contamination. Oxide contamination is much harder to deal with. Oxides get on the wheels either through electrical action (pitting) or corrosion. Alcohol is entirely ineffective in removing oxides. Abrasive cleaning and perhaps polishing will be necessary.

    To clean off oxides, flip the loco over on a workbench and connect track power to it by some appropriate means. A Kadee "wheel cleaning" brush is effective to provide contact to a wheelset but it won't actually clean anything. When the powered wheels are turning, dress them with a mildly abrasive track cleaning block until they shine again. Note that the block will have to have an available sharp corner to get up next to the flange. For non-powered pickup wheels, rotate them by hand and work over the tread with the cleaning block.

    For a large scale loco with really oxidized wheels, use a Dremel tool with a brass wire wheel running against the rotating locomotive wheel.

    If the wheels do not shine after this treatment, or if they get dirty again quickly, consider replacing them.

• Electrical Conductivity Checks. When a loco is on the bench for heavy wheel cleaning, consider checking the pickup of the wheels at that time. A Kadee brush or set of clip leads connected to the track can be moved from wheel to wheel to see that each wheel with pickup capability actually works. Expect some headlight flickering during this test, but the loco should at least run steadily.

  Note that many older steam locos and virtually all brass locos do not pick up power on all wheels. Often the tender picks up power on one rail and the loco on the other rail. Current is conducted between the tender and loco via the drawbar. A DCC installation may modify this situation and more wheel contacts may have been added. A visual inspection will be helpful to determine if any given wheel is capable of power pickup.

  Diesel locos can be tested quickly on the track. Lift one truck off the track and see if it still runs. If possible, further lift wheelsets off the track until only one wheelset remains. Repeat, as possible, for all wheelsets.

  A digital multimeter with an audible conductivity checker can also be used to test individual wheels. When a loco is converted to DCC, there should be no conductivity at the low voltage that the multimeter uses from one side to the other, but the wheels on each side can be checked against each other.

  If a loco fails a conductivity check, the cause of the problem will have to be tracked down. Each part of the conductivity path is suspect, you will have to determine what is there and test the pieces individually. A multi-meter is essential for this level of evaluation.

• Lubrication. All locomotives require lubrication of some kind at bearings and on gears. Loss of lubrication will result in failures. The failures may not happen right away, but a moving surface without lubrication will wear MUCH faster than a lubricated one. Failure of such a surface (bearing or gear) will require replacement of the failed part.

  Basically, if something moves, it will require lubrication of some kind to reduce wear. What kind of lubrication is described below.

  • Lubricants. There are a variety of lubricants that are applicable to model railroad locomotives. There are only three types that are actually needed, gear grease (or a heavy oil), a light oil and a "conductive" oil. Graphite or a composition of graphite and a carrier material can also be useful in some situations, particularly on couplers and pockets.

    There are many lubricant manufacturers and brands with many additives, but in selecting one, you need to pay attention to only two things. The lubricant must be marketed as "plastic compatible" and it must have a good applicator. No matter what marketing buzzwords are used or what additives are included (teflon, lithium, silicone etc) most of them work just fine. Good brands are LGB, AeroCar, LaBelle, Hobe-Lube, or Bachmann.

    3-in-1 oil may work well on a sewing machine, but it is NOT plastic compatible and it will cause most plastics to embrittle and fail, sometimes within hours. Pick lubricants that are clearly labeled as plastic compatible.

    I suspect that some of the LGB lubricants are really just general lubricants intended for other purposes. LGB gear grease looks, smells and feels just like garden variety automotive wheel bearing grease. However, wheel bearing grease is not marketed as plastic compatible. It may work just fine, but I have not used it on plastic. LGB "special" lube is a light oil that sure seems to be a garden variety transmission or hydraulic fluid.

    Pick a container that has a FINE METAL TIP, preferably more than an inch long. This applies only to oils that can be dispensed via a fine tip. The tip is necessary to allow the oil to be applied in small doses and in tight spots.

    Greases are best applied with a toothpick but a squeeze tube will work in many locations and a toothpick can be used to transfer grease from the tip to locations that cannot be reached by the tip directly.

    In ALL cases, you need less lubricant that you probably think. A little can go a long way. Any excess just makes a mess and can get places where it can cause trouble. For example, oil that works it's way to a wheel tread can contaminate the rail on a whole layout resulting the the production of soot that will eventually have to be cleaned off the rail.

    • Oils. Oils are lubricants with a low enough viscosity such that they will flow on a surface and be drawn into bearings via capillary action. Oil should have a very low evaporation rate so that they stay in place. They will all eventually evaporate but lighter the oil, the more quickly it will evaporate.

      • Bearing or "Light" Oil. Bearing oil is the most general purpose lubricant. It can be used as a "make-do" lubricant for practically all places in a locomotive but it's primary usage is for high speed bearings. It is light enough to be drawn into plain bearings but heavy enough to stay around for awhile. It will also soak up into sintered bushings so that it can provide effective lubrication for a long time. Apply it in VERY small doses, a little goes a long way. This stuff will flow along surfaces and any excess can move quite far from where it was placed.

      • Conductive Oil. Conductive oil really isn't conductive. It is formulated for use on conductive joints to reduce wear and to reduce oxidation via the exclusion of oxygen from the surface. It is usually used in VERY SMALL doses on motor commutators (only when needed) and on power pickup wipers. This stuff moves along surfaces faster than light oil.

      • "Heavy" Oil. Heavy oil is sort of cross between a light oil and a grease. It would normally be used only where a grease cannot be applied. The applicators are usually a long plastic tube (the oil has high viscosity so that it doesn't flow well in a syringe type applicator) so that it can be placed into spots were it is hard to place a dab of grease. If you can use grease, use grease instead of heavy oil.

    • Grease. Grease is a very low viscosity lubricant that will typically stay where it was put unless it is flung off by centrifugal force. Grease is used on gear teeth to reduce friction and wear.

  • Motor Bearings. Motor bearings are typically high speed plain bearings, larger ones may be sintered, smaller ones are usually plain brass with a steel shaft. These are friction bearings that require adequate lubrication or they will wear rapidly. A squeal or howl, usually quite loud, is an indicator of a dry plain bearing that requires lubrication IMMEDIATELY. Left unlubricated, the bearing will usually wear unevenly due to imbalance in the rotating parts and if that happens the bearing is usually toast. Use light oil on the most accessible end of the bearing, the oil will work it's way all the way through quite quickly. You will find one of these bearings at each end of the motor.

  • Motor Commutators. An open frame motor usually has an exposed commutator. If the commutator is old, it may want a VERY SMALL drop of conductive oil applied. The oil tends to dissolve burnt on crud allowing the brushes to sweep the, now muddy, crud aside. A residual oil film on the commutator tends to inhibit oxidation of the copper commutator segments. Eventually, this oil will burn and become a layer of non-conductive crud that has to be swept away again. If the commutator doesn't actually require treatment to solve an actual problem, don't apply any oil at all. The graphite component of the brush will provide adequate dry lubrication as the brush wears down.

  • Universal Joints. Most HO locos and some large scale ones use universal joints between the motor and the rest of the gear train. These don't tend to wear a lot and can be left unlubricated as they are usually in a low torque location and made of naturally slippery plastics. I have seen a lot of very old, very high mile HO locos and I've never seen a worn U-joint. If you really feel the need to lubricate a plastic U-joint, use graphite. Metal U-joints should be lubricated with light oil.

  • Gear Tower Worm Bearings. Many HO locos use a gear tower built onto the trucks. At the top of the tower is a worm gear. It rides in bushings in the tower. These bearings, two per gear tower, should be lubricated with light oil. If the locomotive weight obscures one end, then you can be pretty sure that it hasn't been lubricated in a while. Find a way to loosen the obscuring structure to allow the bearing to be lubricated. Oil can be applied to the visible end of the bearing, it will get where it needs to be on it's own.

  • Gear Towers. The gear towers themselves should be lubricated with gear grease. There are two ways to get the grease in there, either from the worm at the top or via the axle gears at the bottom. Since all the gears in a typical gear tower share the same meshing surfaces, grease applied to one gear will work it's way through the whole tower to every gear inside. Idler gear bearings should be lubricated with light oil. It is sometimes hard to get to them, this is where the long slender tip on an oil dispenser comes in handy. Sometimes, those bearings can be accessed from the outside.

    The top of a gear tower can be accessed by prying off the worm cover. It will usually snap in place. This piece usually also holds the whole truck assembly on the loco frame. The bottom cover of the truck can be removed by carefully prying some clips that hold the cover in place. It is usually necessary to insert a small screwdriver between the cover and frame after the first few clips are released so prevent the first clip from relatching while the 2nd clip is being released.

    Some locos, especially geared steam locos, have intermediate reduction gears that do not provide a common face to each other. In that case, one must apply grease to each part of the train to allow grease to get to every gear.

  • Worm Gears. Worm gears are used in lots of places besides inside gear towers. The worm itself is usually metal, it's mating worm gear is usually plastic. The worm is harder to replace than the mating plastic gear. I have also seen metal worms on metal gears, plastic worms on plastic gears and plastic worms on metal gears. In any case, a worm should be lubricated with a grease. A heavy gear oil is the next best.

  • Axle Bearings. Axle bearings carry the loco's weight. These are usually plain bearings, although many large scale locos use ball bearings. Plain bearings (axle in a slot) should be lightly greased. If it is a bushing, use a light oil. If it is a conductive bushing, use conductive oil although a light oil will rarely damage electrical conductivity on a load bearing bushing. If the loco is one where the truck side frame actually carries the loco weight (Atlas, Kato, older Aristo-Craft and others) then the bearing surface is probably an electrical contact as well. These should be lubricated with conductive oil or light oil. Conductive oil doesn't have the staying power of the heavier oils so that these may need attention more often.

  • Connecting Rods and Valve Gear. The connecting rods, crankpins and valve gear of steam locos should be lubricated with very small amounts of light oil at each joint that rotates or slides.

• Decoder Maintenance. A good decoder should never require periodic maintenance. Once the programming is done to set the loco up in the first place, it should never change on it's own. Decoders that reset themselves and require a reload of their programming should be scrapped and replaced with another kind.