Life-like E7&E8 's

Life-like E7&E8 's

Post by MLITTL » Thu, 24 Apr 1997 04:00:00



I have three Life-like E8-9 Units two of which were broken in at the same
time running back to back . I just purchased a set of the hte new E7's
breaking  them in the same way so the y would run together.   My question
is Why d o the E7's run faster than the E8"s? I run these on a large
modular layout ( 42x 18') and had hopes of running two trains at once, as
we do with other units. I thought the motors and the gearing were the same
. Any one got any ideas?

 
 
 

Life-like E7&E8 's

Post by David Redmo » Thu, 24 Apr 1997 04:00:00


Quote:

>  I have three Life-like E8-9 Units two of which were broken in at the same
>  time running back to back . I just purchased a set of the hte new E7's
>  breaking  them in the same way so the y would run together.   My question
>  is Why d o the E7's run faster than the E8"s? I run these on a large
>  modular layout ( 42x 18') and had hopes of running two trains at once, as
>  we do with other units. I thought the motors and the gearing were the same
>  .. Any one got any ideas?


I'll look more carefully, but I think one difference is that the starting voltage is different
between the two models.  I would guess this relates to some difference in the lighting
circuits.  The effect is that the actual voltage applied to the motor is offset between the
two models.  Also, the E-8's have different offset or starting voltage running forward
compared to running backward due to the constant lighting circuit.  At least this is
my impression.  Maybe someone can check this out more carefully and post results?

Most of my P2K stuff is awkward to run because there is an offset of about 2 volts before the
motor starts to see power.  This is true across the GP18, SD7, SW1200, and E8.

Opinions expressed herein are my own and may not represent those of my employer.

 
 
 

Life-like E7&E8 's

Post by Douglas E. Menk » Thu, 24 Apr 1997 04:00:00


Quote:

> I have three Life-like E8-9 Units two of which were broken in at the same
> time running back to back . I just purchased a set of the hte new E7's
> breaking  them in the same way so the y would run together.   My question
> is Why d o the E7's run faster than the E8"s? I run these on a large
> modular layout ( 42x 18') and had hopes of running two trains at once, as
> we do with other units. I thought the motors and the gearing were the same
> . Any one got any ideas?


I have lots of ideas. Which one you want to hear? ;-)

Your problem is not unique. In fact, If you check carefully, I think
you'll find that even your E8's don't run the same speed back to back.
The lighting circut is stealing some of the voltage (about 1.5 volts)
from the motor when it runs forward, but does not when it runs in
reverse. All of my E8's run this way. (I have had 12 total)

Now, as for the E7, I don't have any of these, they haven't released my
road yet (CB&Q), but I have had other P2K locos that where grossly
mismached in speed. The GP18's will not MU with the SD7/9's. The SD's
are way too slow. My SW9 won't MU with anything but another SW9. That is
one of the great problems with trying to keep prototype fidelity. If you
motor and gear a model to run in the same speed range as the prototype
(as per P2K policy) It makes them very hard to run together. Besides,
the power unit of the E7 is the same basic design, but it is not
identical. They may have used different motors and/or gearing. Hard to
say for sure.

Now, what to do about it. Here are 3 options listed in order of expense.

Option 1. Put a resister in series with the motor of the faster loco to
slow it down to the speed of the slower loco. This obviously requires a
little trial and error. Resisters also put out heat, so they need a
little space and a little airflow. There are holes in the P2K shells for
vents and such, so that probably won't be a problem.

Option 2. Remotor one or more of the locos to better match the speed.
You could replace all the motors in all the E series (assuming they all
have the smae gearing) with an known RPM can motor, or remotor the fast
ones to slow them down to the slower ones.

Option 3. Switch to DCC and ust the adjustable speed tables in the
decoders to match the locos electronically. Yet another reason to make
the big leap to DCC. Obviously the most expensive option.

There is a 4th option. If the speed difference is not great, put the
slower one in front, put a little longer train behind them, and let'em
run. Having the faster train at the rear will spilt the pulling power
between the two. The weight of the train will slow the fast loco down
below the speed of the first loco, and they share the load without the
"tug of war" that occurs without the train behind them. If you put the
slow loco in back, the fast loco ends up pulling both the train and the
slower loco, resulting in wasted power.

Doug Menke

 
 
 

Life-like E7&E8 's

Post by Phil Hartun » Thu, 24 Apr 1997 04:00:00


[SNIP]

Quote:
> I'll look more carefully, but I think one difference is that the

 starting voltage is different between the two models.  I would guess
 this relates to some difference in the lighting circuits.  The effect
 is that the actual voltage applied to the motor is offset between the two
 models.  Also, the E-8's have different offset or starting voltage running
 forward compared to running backward due to the constant lighting circuit.
 At least this is my impression.  Maybe someone can check this out more
 carefully and post results?
[Snip]
Since I have dealt with this problem, I'll respond with my experiences.

I bought my first E-8 (UP #928) about 3 years ago when they first came
out. (super nice too!!!).  Loved the mars light, etc.

This winter, I while calling all over the country to get interiors for my
Rivarossi UP cars, I found a hobby shop that had a UP #949, so I bought it
(since my era is 1985-1995).  I then traded #928 for a #951 that Bill
Gripp had.  When I got them both I experienced the same problem in that
the loco runs faster in reverse than forward (for the same voltage
setting), causing the "rear" unit to push the forward unit, and with the
swivel coupler mount, this causes some derailments on crossovers.

I opened up the units, removed the circuit board and figured out how the
lighting works.  Here is an ASCII schematic (does not apply to Mars light
models, but it would be similar.

----+---|>|------|>|---+----|>|--+-------+
T   |                  |         |       |
R   |                  +---bulb--+       |
A   |                            |     Motor
C   +---------|<|----------------+       |
K                                        |
-----------------------------------------+

The extra diodes may be carried over from the Mars light circuit, but what
this does is provide about a 2v drop in the forward direction and a 0.7
volt drop in reverse (resulting in higher reverse speeds).

What I did to make it work...

I moved the wire to the bulb from one point on the circuit board to a
point where the bulb runs in reverse (basically flip the input/output of
the diode circuit).  I don't specfically remember which hole I moved it
to. (I'm at work and the E units are at home...)

Now my units run back to back with no problem, lights on in one direction,
off in the other.  Converting these to DCC would eliminate this problem as
well.

If you would like more information please e-mail me direct at

Phil