Bergs (Minimodels) Sydney Electric Cars - Traction Tires

The two powered axles of the powered car were supplied with traction tires. I am not so keen on traction tires as they often don't run true (i.e. they wobble), they can wear out relatively quickly and they reduce the number of wheels used for power pickup.

When I bought the set, I bought a spare set of non-powered axles (2 axles = Spare Part No. 32) with a view to replacing the traction tires. I was expecting the spare axles to have gears fitted and that they would be a "drop-in" replacement for the original driving axles, but they did not have gears.

I used the spare wheelsets I bought to replace the end wheelsets of the non-powered motor car, as these axles had splines in the centre (for a gear) and also splines at the ends for the wheels (to prevent slippage). It was then relatively simple to remove the solid wheels from the now spare splined axles, and use these to replace the original driving wheels which had the traction tires, using the original geared axles. When I removed the wheels, I was careful to leave the plastic centre bushes on the axles, and just remove the metal wheels, to minimise the risk of introducing wheel wobble.

Overall, the operation was a success and the motor car now has 8-wheel pickup and still 4-wheel drive. Without the traction tires, it has enough tractive effort to haul the 4-car train up my grades which are around 1 in 80. It also manages without slipping on my branch line which has a section of 1 in 40 grade.

Based on other information on the web, the prototype trains has a reputation for wheelspin as each power car was only powered on two axles. (The powered axles were both on the long-wheelbase power bogie, compared to the model which is powered on one axles of each bogie.)

The design of the model bogies is a bit unusual in that they clip into a turntable which fits into a round opening in the floor. The individual bogies can rock freely fore and aft which is good for accommodating ups and downs in the track, but they have almost no rocking movement side to side. Because my layout has superelevation on the mainline curves, the power pickup is not so good at some spots, particularly at the transitions between curves and straight track where the superelevation changes from maximum to zero over approx 300 mm. At these transitions, the weight of the power car is not evenly distributed over all wheels. The bogies on the non-powered cars are identical minus gears and pickups, but the lack of transverse rocking doesn't seem to adversely affect their tracking.

Another unusual feature of the bogies is that the central mouldings are identical for all bogies, and they have two sets of axles slots to suit the short wheelbase non-powered bogies and the long-wheelbase powered bogies of the prototype.