Aristo Power Brick Tune-up

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old brickAll the pre-1999 Aristo diesel products use the same truck assembly which is modeled after an AAR type B truck that was often used on Alco and early GE equipment. The information on this page applies equally well to the U-25B, FA-1, FB-1 and RS-3 manufactured roughly through the end of 1998.

This brick was from one of the latest locos made with the non-ball bearing brick, a 2nd generation RS-3. There is only one connector on the brick itself, a blue/green pair for the motor only. Power was conducted to the frame from wires connected to the sideframes. The motors on this version used a 3 pin connector that plugged into the bottom of the frame. The power (usually a black/white pair) used a similar 2 pin connector that also plugs into the frame.

One version older bricks (usually black box locos) used red in-line connectors for both the motor and power. The motor wires were still blue/green but the power wires could either be black/red or black/white. These then plugged into a 4 pin connector on the board inside the loco.

Even older versions (mostly blue box) didn't have the red in-line connectors. The wiring harness from the brick and sideframes went directly to a 4 pin connector inside the loco.

old brick insideThe main spotting features of the old brick are the axle extensions at each wheel. This is a late version of the "old" brick taken off an RS-3. The even older versions have lash screws at each end of the brick to set the axle play as discussed below. Even older versions don't have the plastic hub on the wheels.

The axle ends fit into brass bushings on the truck sideframes. The engine is actually suspended from these axles and bushings via the sideframes and some springs. The axles are also used for power pickup via the bushings and some wires connected to brass straps on the sideframes that contact these bushings.

The older bricks may have a brass or plastic universal joint. Be careful when you take it out, sometimes the metal rods in the universal fall out.

new brickAs of 1999 a new design appeared that is significantly different. The new design has ball bearings and the axles do not extend to the sideframes. The wheels are held on with screws at the center of each wheel. This page is relevant only to the older design.

The newer bricks pick up power via the ball bearings inside the trucks. The engine is suspended via the tabs on the sides of the bricks and the sideframes are for decoration only.

This brick is taken from a Doodlebug that does not have frame mounted connectors. There are pigtails hanging out from the bottom of the Doodlebug to make contact with the red connectors. The connectors are keyed backwards so that it is not possible to mis-connect them.

Newer locos with a distribution board and DCC socket inside usually have the 2 and 3 pin connectors facing downward from the frame to connect the bricks.

ball bearing brick insideThe new brick differs significantly inside too. This brick has ball bearings at each wheel and power is picked up through the bearings. Therefore, there are power contact straps inside and an extra pair of wires leading from each brick. The motors have a noise suppression capacitor already installed. This brick doesn't seem to suffer the same binding issues as the older one so the notes below have little importance for this design.

replacement brickIf you have a U-25B, FA-1, FB-1 or RS-3 with the older bricks and one or both are too far gone for remedial work, you can get a replacement ball bearing brick that will fit your loco. These also fit the RDC and Doodlebug. The ART-29351 is a brick/sideframe assembly with wiring harness that fit both the older and newer types of locos. If you loco is really old, it MAY require some wire splicing but the brick will still fit.

These bricks run at the same speed as the older ones so they don't have to be changed out in pairs. A single assembly as shown in the photo can be found for about $50 at various online retailers.

I have this one wired to test as an individual brick. My intention is to use it to replace the brick under a Bachmann trolly.

Most Aristo diesels are smooth running engines, but there are some that are unsteady at low speeds. This is caused by the motor, which are inside each truck, running at different speeds due to changes in loads on that brick. One brick wants to run faster than the other and they fight each other. This does not have to happen and with a little work, gear grease, heavy gear oil and a few scraps of thin styrene, EVERY brick can be made to run very well.

A major problem with some bricks is that the brick case halves pinch the motor bearings adding unnecessary drag. This can be prevented by shimming the case halves apart with the aforementioned styrene scraps, although any small piece of shim material about 20 mils (0.5 mm) thick will do.

Sometimes an Aristo brick will develop a loud squeak. This is usually caused by a dry joint between a motor shaft and a lash screw. You should lubricate the brick, but to temporarily solve the problem, try to determine which truck the squeak is coming from and turn the lash screw furthest from the rocking gearbox counterclockwise about 10 degrees. If this doesn't do it, try the other lash screw.

There is a universal joint inside each brick. Sometimes this joint comes loose and slips on either the motor shaft or a gearbox shaft. There were two types of universals used in various production runs, a metal one and a plastic one. The metal one is the most likely to slip. Slippage is indicated if the axle in the rocking gearbox does not turn at all. The universal has two very small setscrews on it, one or both of them often tends to loosen. These screws are so small that it is easy to damage them. Before you go in there and gouge up a setscrew, find a jewelers screwdriver that fits the full length of the screw slot and is thick enough to just fill the slot. If you use the wrong screwdriver, you'll likely damage the screw requiring a replacement IF you can get the old damaged screw back out.

To do internal work, you'll need to have some lubricants handy. You can get away with just three types.

General oiling can be done with LGB 50019 Special oil which works very well for all light oiling applications such as shaft bearings and bushings.

Gear lubrication requires a heavy gear oil or grease such as LGB 51020 gear grease or HobeLube HL655 gear oil.

Electrical contact lubrication requires a conductive lubricant. There are several types available from Bachmann, AristoCraft and others.

Whatever lubricants that you use MUST be plastic compatible. Many general lubricants, like 3-in-1 oil, will eventually attack plastic.

Before you tear into the bricks test your loco to see if you actually should do anything.

Do the same to the other brick if it needs it.

When you are all done, the engine should run with no hint of hesitation or jerky operation.

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© 1997-2009 George Schreyer
Created before Sep 18, 1997
Last Updated May 23, 2009