Bachmann A4 (Split Chassis)


Bachmann A4 (Split Chassis)

Postby Trains4U » Mon Jan 21, 2008 10:00 pm

Fitting a Lenz Standard Decoder to a Bachmann A4


A little light on photos this time, but hopefully you will get the idea...

The body is held onto the chassis by a screw at each end. One under the pony truck at the front, and one under the Cartazzi truck at the rear. The body just slides straight off.

as you can see you are left with one of thos ghastly split chassis arrangements :wink:
(The job is actually not that difficult, provided everything goes to plan)


The first task is to remove the keeper plate and allow the driving wheels to drop clear of the chassis.

Unplug the cylinder blocks from the chassis (Circled in green) - sometimes these are firmly glued in place. If so, do not attempt to remove them. the next stage will be more difficult, but not impossible.

Do not attempt to remove the bracket circled blue - this is firmly glued and cannot be removed without risk of damage.

Remove all the screws (Circled red)


Carefully spreading the chassis halves, lift out the motor. (This can be difficult if the cylinder blocks cannot be removed)
Trim the wires on the decoder to approximately 2", slip some heat shrink over the orange and grey wires, then solder them to the motor terminals. Cover the motor terminals with the heatshrink and secure using the soldering iron


Remove the brass springs and foam squares from each half of the chassis and re-fit the motor. The wires should protrude from the rear of the chassis.
Re-assemle the chassis and carefully refit the driving wheels, ensuring they are properly aligned.


The red and black wires from the decoder can then be soldered to the brass plates provided at the motor end of the chassis.

the final job before testing is to ensure that the rear of the chassis is well insulated to prevent the decoder from causing a short circuit.


Test the locomotive, if it runs backwards, swap the black and red wires over. It may be necessary to make minor adjustments to the driving axles if they are not properly aligned.

Then simply pop the body back on, re-fitting the two screws, and you are ready to go (Or in this case, off in the post to Disco-Dave)

All in, between 25 and 40 mins work, depending on what has been glued where.

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