Power Functions Train Motor Testing Information
by Mark Bellis June 2010

The 9V train motors set the standard for train motor tractive effort.
A typical 2-motor loco could pull another two carriages of its own
weight up a 1 in 30 slope at PF IR Receiver speed setting 4 without
stalling, and could descend a 1 in 30 slope at speed setting 4 without
running away and derailing.

By comparison to the 9V motors, the RC train motors were not up to the job.
They stalled when going up the hill, tripping the PF LiPo battery overcurrent
trip (800mA), and ran away down the hill, derailing the train.

Therefore, it is essential that the new Power Functions train motors pass
this test, so that AFOL train enthusiasts can have confidence to use them as
drop-in replacements for 9V train motors.

A standard test coach was used, based on a Mk1 UK coach.
The coaches are heavy and have considerable drag in the curves.
The coach was fitted with two motor bogies, a PF LiPo battery and a PF IR receiver.
For the PF Train motor test a pole reverser switch was used, so that the wires of
the two motors could both face towards the couplings at each end.
The threshold of a 'pass' compared to 9V train motors is to pull  two similar coaches
at speed setting 4 both up and down the 1 in 30 slopes of the layout.
The PF train motors passed the test comfortably.

Having passed the test, a further passenger train test was conducted, to find
the limit of operation.
Note that with 9V motors it would be usual to have two motors in the loco tender and
a further two in the first carrage in order to pull three more carriages.  The supply current
rises to about 1300mA for the 9V train with four train motors.  The loco has two type-
43362 gearmotors to turn the driving wheels, and lights in the firebox (3x 9V light bricks).
An additional coach was added to the 3-coach train.  Speed setting 4 was not always
a sufficient power level to ascend the slope without stopping.
Speed setting 5 succeeded most of the time, with an occasional overcurrent trip
because the tractive load is more than 800mA!
The coaches stayed on the track (just!) when descending at speed setting 5.
The result is that a train with 4 motors would comfortably pull this load, substituting for
four 9V train motors, but some innovation would be required if it were desirable for two
PF LiPo batteries to load-share safely in order to keep the four motors pulling equally,
rather than just having the loco and first coach as independent vehicles set to the same
PF IR channel.  The key is whether IR reception is reliable for both vehicles together,
because of one pulled or pushed the other, it might lead to a derailment.

A goods train test was also conducted.
Nine goods wagons and a brake van were in the train.
The test coach was run as if it were a bogie diesel loco.
The train was able to run right round the layout, both up and down the slopes, at
speed settings 3 and 4.  This means that it is possible to leave slow and fast goods
trains running at different speeds.  One aim at a railway show is to leave a train running
and talk to the public because this enhances their experience.  The good level of torque
and speed regulation provided by the PF train motors enables this to be achieved.
This is an encouraging result for AFOL train enthusiasts.

I noticed during the tests that there was a good level of torque at the lowest speed settings
when climbing the hill.  This looks good for running long trains slowly, which is typical
in the US.
I had no problems with grip but I was using a heavy carriage.  This didn't have any
problems with the RC motor wheels but other people had found problems with them.
There are new grippier wheels with the PF train motor.
I might conduct some more specific tests later.

Mark Bellis
June 2010