BBT - Barry's Big Trains

This page under construction, so please be patient. TOC and I are trying to document as much as possible of Barry's work. (especially in light that we can no longer contact Barry)


First of all, this page would not be possible without the hard work and kind help of Dave Goodson. Thank you for this (and many other things) Dave!

Barry Olson made a number of well and lesser known improvements in drive mechanisms for large scale trains, but he is best known for the replacement BBT drive for the Bachmann Big Hauler.

This will also be a place to honor Barry for all his contributions, and if you have a different BBT loco and would wish to share it, please email me.

From one of Barry's advertisements:

 "Barry's Big Trains offers several products to upgrade your Bachmann 4-6-0 and can also manufacture a custom drive to your specifications.

There's the standard 4-6-0, A 2-8-0 Narrow Gauge conversion, and a 2-8-0 Standard Gauge.  All drives come standard with the horizontal motored direct drive or with the optional vertical mounted motor countershaft drive.

We also have a new product, the replacement drive for the Bachmann Anniversary 10 wheeler.  It features an equalizes front axle, comes standard with the countershaft drive, a reed chuff switch, three-segment siderods on the 2-8-0 version, and all of the usual BBT features.

For more information about our custom drives contact us at by using the contact information below."


The "standard" BBT 4-6-0 Big Hauler


The hallmark and central feature of this most known BBT conversion is the extruded aluminum frame/chassis. This was a custom extrusion.

The following pictures show several things, the first is the replacement pilot truck.The one shown is 2 pieces of blackened aluminum angle, about 3/8". The wheels and axles are standard 4-6-0 components, but since the plastic spacer in the center often cracked on it's own, he would often replace them with ones he machined to a slightly larger inside diameter so they would not split.

You can see the Plexiglas  spacer block holding the sides in position, and the stainless steel "tang" from the chassis to the pilot.

 BBT4 6 0 004

BBT4 6 0 005

In the picture below, you see the first axle is within a brass tube, which houses the flanged ball bearings and the axle is inside. There are 2 "L" brackets on either side of the front axle, and the screw and tube on top constrains the axle assembly. There is a little up down movement for flexibility.

BBT4 6 0 006

Below is a closer picture of the assembly.

BBT4 6 0 007

The picture below shows the screws that hold these "L" brackets in place and the front screw doubles as the pivot point for the tang to the pilot truck.

BBT4 6 0 008

This side view shows the segmented side rod, necessary since the front axle has about 1/4" up down travel.

BBT4 6 0 009




So there were several options.

One option was to stay with the Bachmann Drivers, you sent yours in, they were cored and a delrin insert was added for the axle. The wheel contour was "cleaned up", and the contour was reprofiled to match Sierra Valley profile. (the flanges were narrower, not as high, etc.)

Another option that added $90, you got 2" BBT cast brass drivers with a stainless steel tires.



Non-segmented laser cut stainless siderods. Non-pivoting front axle. Stock axle spacing. With BBT real lead weights installed.

Stainless axles, Delrin inserts in cored drivers, Screwed onto axles. Ball bearings on 1 & 3 axles. Ball bearings on gear crossshafts.


BBT4 6 0 010

BBT4 6 0 011

Different 4-6-0 variation:

This is the installed oddball 4-6-0. Custom metal running boards, scratch-built whaleback tender, Delton cylinders and single crosshead, etc.

BBTC&C 4 6 0A

BBTC&C 4 6 0B

Unequal axle 4-6-0

This is the rare 4-6-0 chassis with unequal axle spacing. Non-pivoting front axle. Non-segmented siderods.

BBT4 6 0 001

BBT4 6 0 002

BBT4 6 0 003

BBT4 6 0 012

Additional weights for the 4-6-0:


The weight in the back is 2" long x 1-3/8 wide by 1-5/8 tall, and has a hole in it for the existing stud, and you have to counterbore it a bit because there is a bit of a reinforcing ring at the base of the stud.

The weight in the front is 3" long x 1-1/2" tall, and 1-3/8" wide, about 1-1/4 there is a 5/16" hole to fit over the stud, and there is a recess in the bottom that is 1" long and 1/4" deep to clear the valve gear.

This is for the vertical motor.


The older setup with the horizontal motor takes a different weight.

(pictures courtesy Dave Goodson)

BBT weights 001

BBT weights 002


BBT weights 003

2-8-0 BBT

Palacina drivers, segmented side rods, pivoted front axle, built before BBT running boards so made up extensions and brases, CSC tank.

BBT2 8 0 004


BBT2 8 0 005

Anniversary 2-8-0

Smaller cast brass BBT designed drivers (1-3/4") with stainless tires, Segmented side rods, pivoted (equalized) front axle. CSC tank.
HEAVY weights.

BBTA2 8 0 006

BBTA2 8 0 007



The options for 2-8-0's were similar to the 4-6-0 drivers.

He also had cast brass drivers with stainless tires made, these were 1-3/4", and had the "smiley" counterweights, and they were originally for his C-16 project that he wanted to build as a kit.

An older option was Barry used Palacina Productions drivers, but he wanted a better driver, the Palacinas were pot metal. Also the spoke count was wrong.

early 2-8-0

This one is early BBT, Palacina drivers, segmented side rods, hinged (equalized) lead driver axle, with BBY milled aluminum loco running board kit, and CSC oil tank in tender.


 BBT2 8 0 010

BBT2 8 0 011

2-8-2 Mikado

Barry built these on custom order. This is one boiler variation, extended, backhead stock location in cab. I have another boiler if you want photos.

This one uses stock (cored) Bachmann 2" drivers, segmented, pivoted, BBT running boards (long version) and CSC tank. Bigger weights than normal, as much longer rear course in boiler due to extension.

Rear frame extension of aluminum extrusion off top of stock 2-8-0 drive, standard custom BBT lead and trail trucks.

BBT2 8 0 001

BBT2 8 0 002

BBT2 8 0 003


Barry did have custom siderods made.

on-segmented laser cut stainless siderods. Non-pivoting front axle. Stock axle spacing. With BBT real lead weights installed.

Stainless axles, Delrin inserts in cored drivers, Screwed onto axles. Ball bearings on 1 & 3 axles. Ball bearings on gear crossshafts.

BBT4 6 0 010

BBT4 6 0 011


From Barry's instructions for the BBT 2-8-0 drive:


The BBT DRIVE 280 requires the addition of a weight of about three to five pounds to provide adequate traction for the new power. I had intended to provide these weights as an extra- cost item, but the availability and price of lead and the cost of shipping have ruled this out. Therefore, please consider the following drawings to cast your own weight. The mold is made up of 2 x 2 boards on a plywood or particle board base. The actual dimensions of a 2 x 2 are 1 5/8" thick by 1 5/8" wide. Filled with lead this size will yield a weight of four or four and a quarter pounds (2 kilos). You can produce more than one weight from this mold. Screw the boards down and un-screw them when the lead has cooled, pound out the 3/8" dowels for the posts. In multiple casts, use new posts for each application (although I have been able to reuse these post for a few weights). The wood should be fairly dry, and there will be a bit of smoke, but the end product is just fine (keep some water handy, sprinkle it on if a flame develops).

NOTE: Some owners of the BBT DRIVE 460 are running weights up to SIX pounds. No known complaints, yet. More weight seems to provide more traction. We don't know the limit. Just as in prototypical applications the pulling capability decreases rapidly as the percent of incline increases. Your old cast-iron weight can be attached to the top of this weight, if it doesn't interfere with the boiler top.


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