Large Scale Central

USA Trains motor block remedy

To repower my Bachmann trolley, I bought a USA Trains motor block.

Problem: A test of the block was frustrating as no electrical contact with the shoes or wheels would power the block. However, the two protruding sets of “rods” out the back of the block would activate the motor – but only one each out of the double set sticking out provided power. I found this puzzling until I took the motor block lid off.

Remedy: Open this same lid of the block - six screws - not the bottom side or wheel side. Once opened, notice those same doubled rods entering and exiting the block. It becomes obvious that the motor is directly connected to only one each of those same rods. Still, those connecting rods do not run to the bottom of the block to connect the wheels and shoes. They only run to and exit from the back of the block! However, the other two do run down to the bottom whereby they are electrically connected to the pickup shoes and the axles. BUT, these same rods are NOT connected to the motor. So the remedy is to join the two parallel sets of “rods” – which are easily seen with the lid off – so there will be power power from the shoes and axles. I used a very small washer to lay across the double rods – compressing this washer using an existing screw. Do the same for both sets of double “rods”.

Once you remove this top lid, you will easily see these double rods and the location for the washer to make this cross-contact between the two rods.

Wendell

Ah, yea.

That is so on the locomotive one can have power in for lights and such, and then power out to the motors. This makes it so the motors can be isolated from the power pick ups for stuff like RC/battery, or DCC, or having the lights on, but the motors off on DC analog tracks.

It is wired so that the motor leads are independent from the track pickups intentionally, otherwise you could never fit a decoder to a USAT loco.

This page has a number of pictures and information that might be helpful to others trying to understand the block:

http://www.elmassian.com/index.php?option=com_content&view=article&id=648&Itemid=893

The “rods” inside are just visible inboard of the axles: