O-31 Operation - M.T.H. PA B-Unit Operating Instructions Manual

Before the new tire can be installed, you must make sure the old tire has
been completely removed from the groove in the drive wheel. Use a razor
blade or small flatblade screwdriver pry away any remains left from the old
tire that may still be in the drive wheel groove. Once the old tire has been
completely removed, slip the new tire onto the wheel. You may find it
useful to use two small flatblade screwdrivers to assist you in stretching the
tire over the wheel. Be careful to avoid twisting the tire when stretching it
over the wheel. If a twist occurs, the tire will have to be removed and
reinstalled or a noticeable wobble in your engine will occur when operating
the locomotive. In addition, it is important to make sure that the tire is
fully seated inside the groove. Any portion of the tire extending out of the
groove can cause the engine to wobble. A razor blade can be used to trim
away any excess tire that doesn't seat itself inside the groove properly.
Once the new tire(s) are in place, reassemble the truck sides to the truck
blocks and then reassemble the chassis to the body. Replacement tires are
available directly from MTH Electric Trains.

O-31 Operation

While the MTH PA B-Unit is more than capable of operating on O-31
curves and switches, you may find that certain light freight cars are prone to
derailing when being pulled or pushed by the MTH PA through O-31
switches. Should this occur, we suggest adding weight to the cars making
them heavier and less likely to derail.
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Premier PA B-Unit Operating Manual