|The GregTrain Takes Its First Ride - Jan 14 2009|
|So our first REAL test of the "gas over electric" loco
was a terrific success.
Here is what we did on Wednesday, January 14, 2008
We meet at Modern Effects
in Pacoima to load the new LOCO and RIDING CAR onto one of Garry
Elmendorf's flat bed trailers, then head off to Los
Angeles Live Steamers at Griffith Park, CA. Its only about a
20 minute drive so we arrived, ready to roll around 11:30 AM
Kristman, a friend and another LALS member, came out and helped introduce
us to the club layout as well as understand the lift/transfer system at
the club so we could off load our new Loco and Riding car. Our Loco
is only a chassis at this point in time.
Erik and Garry piled on the back of the riding car and we head down
the track where we met up with Miles and his consist. Miles led the
way as we made our first trip 'round the club.
I had originally designed the system to operate with a 2:1 reduction
on the main drive system. However the more I worked with the numbers,
the more I began to think that I had plenty of horse power and that 2:1
was not necessary. Our first run used 1:1 on the upper drive shaft.
Though we seemed to have plenty of horse power, the system was WAY too
fast. I had to keep backing off on the throttle and we were barely
above idle. Indeed it seemed that if I had the 2:1 reduction on the
top drive shaft, the loco would have been more responsive.
On the bench, I had already tried re-wiring the two DC drive motors
in series instead of parallel. When I did this, the drive motors
turned exactly 1/2 as fast and seemed to share the power load much better.
However, this test was done with the motors wired parallel.
After several runs around the inner loop, I decided to try a load test.
Miles brought his 5 car consist around behind my 2 car test train, we disengaged
his drive and I towed his train and mine around the inner loop. Horse
power was NO problem. I had a traction problem. I could spin
my wheels easily.
At this point, I decided that it was time to lower the voltage to the
drive motors by series wiring them. I had forgotten the special cable
I had made for such a test so it seemed like lunch was in order.
Miles was not feeling well so he head home. Garry, Erik and I
head out for a sandwich and a trip back to Garry's shop to pick up my "series
Soon we were back a LALS and ready to roll.
Sure enough, when the motors were wired in series (1/2 the voltage to
each motor) everything worked much better. We could accelerate more
smoothly and the engine was much happier at cruising speed with the main
alternator putting out about 80 volts.
A couple of trips around the loop and even one heading WAY out to the
West end and we were all happy that our calculations were correct.
We loaded up everything and head back to Modern Effects (Garry Elmendorf's
Shop). We were done by about 4 and congratulating ourselves at Modern
Effects by 4:30.
All in all it was a GREAT DAY. The weather was terrific, the train
worked like a charm and we all had fun.
The next job is to install our braking system and refine the series
/ parallel system. It occurs to us that we need to easily be able
to switch between series and parallel motor operation. For shuttling
and maximum control and horse power, series wiring is the best. However,
at cruising speed, we think it would be great if we could switch to parallel
wiring and then drop the engine RPM to half. We have plenty of HP
so why not have a two speed system.
Since it is my plan to have a microprocessor in control of and monitoring
everything, it would be easy to set an RPM / Current / MPH point where
the system would automatically switch from parallel to series...
Something to think about.
Thanks everyone for your help on this fun project. Its nice for
all of us to work on something that is not going to be in a movie....
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