[HOsteam] Actual "TE" test results


Tom Knowles <ncstl@...>
 

Hello to the list again, esp you, David,
I'll try to keep this brief, sorry 'bout my "exponential expoundments". I
did go right out to the train room with the postal scale and tho' the
results are not definative, they are an indication. We had an emergency
visit to the Vet today, so have been gone all day.

First, the cheap, plastic scale was zero adjusted so the platen would set
the pointer on zero when held sideways. There was a little binding of the
movement in this position, but it was all I had! So first I tried one of
the Brass Decapods. An old PFM one that has been remotored with a can motor
and is well broken-in, believe me. I used the scale to "catch" the engine
in motion on a code 70 passer that runs at the edge of the layout. I just
let the engine push the platen with it's coupler. I believe test results
would be higher on code 83 or code 100 rail and perhaps on brass rail, too.
Free running speed was maybe 30 SMPH, or about 4 volts. Just enough to slip
the drivers a bit when stopped. Second I tried the same in the reverse
direction. Repeat the test for average and verifications. I did the same
test with a Bachman 4-8-2, and one of my Mantua mike re-dos.

2-10-0 Russian, brass model: fwd 2.0 oz .TE ; Rev, 2.3 oz.
4-8-2 USRA: plastic/metal: fwd 1.8 ; rev, 2.0
2-8-2 Mantua, cast Zamac: fwd 2.4 ; rev, 2.4

These numbers reflect the ability to pull approximately 25 to 35
free-rolling cars on level track, and seems about right for a 2-10-0 or
0-8-0 prototype, but way low for the mike and the mountain. Curiously, these
numbers are higher than expected "corrected" to scale numbers. I guess
model locos are asked to do more work in proportion to their prototypes due
to sharper curves and other factors so need to have more power relative to
thier size.

I know MR and other magazines have more sophisticated test set-ups, and
regularly publish new product's results, including TE (An example is an
On21/2 Porter 0-4-0T did 1 oz.and a Kato SD40 did 2.8oz) but this way I
can judge any inmprovements here at home, and so can you! I definitely plan
to add some lead to the Mikes as a result of these comparisons.

This was a fun little diversion, and I am interested to hear what results
other might get.

Keep steamin'
Tom K


Starr, David <david.starr@...>
 

Well, maybe I'll drop by Staples and see what they have for cheap scales. The
kitchen type scale I use for weighing rolling stock just won't go sideways for
measuring tractive effort.
High school physics suggests that TE for any model that can spin it's drivers
is about 0.2 (coefficient of friction metal on metal) * weight on drivers. The
diesels usually pull better than steamers which I attribute to more weight and
all wheel drive so all weight is on the drivers, no unpowered pilot or trailer
wheels. Seems to me you either add weight, or go with traction tires or double
head...
The "straight & level track" is plenty good enough. It's the grades down at
the club, we cross the Appalachians with better then 2% grade. As is, the
Pacific can get 7-8 cars over the ridge by itself. If I double head I can do
about twice that.


David J. Starr
Senior Systems Video Engineer
Computer Products Division
781 937 1518
HTTP://www.analog.com/industry/video

----------
From: Tom Knowles[SMTP:ncstl@mindspring.com]
Reply To: HOsteam@egroups.com
Sent: Saturday, 12 August, 2000 10:49 PM
To: HOsteam@egroups.com
Subject: Re: [HOsteam] Actual "TE" test results

Hello to the list again, esp you, David,
I'll try to keep this brief, sorry 'bout my "exponential expoundments". I
did go right out to the train room with the postal scale and tho' the
results are not definative, they are an indication. We had an emergency
visit to the Vet today, so have been gone all day.

First, the cheap, plastic scale was zero adjusted so the platen would set
the pointer on zero when held sideways. There was a little binding of the
movement in this position, but it was all I had! So first I tried one of
the Brass Decapods. An old PFM one that has been remotored with a can motor
and is well broken-in, believe me. I used the scale to "catch" the engine
in motion on a code 70 passer that runs at the edge of the layout. I just
let the engine push the platen with it's coupler. I believe test results
would be higher on code 83 or code 100 rail and perhaps on brass rail, too.
Free running speed was maybe 30 SMPH, or about 4 volts. Just enough to slip
the drivers a bit when stopped. Second I tried the same in the reverse
direction. Repeat the test for average and verifications. I did the same
test with a Bachman 4-8-2, and one of my Mantua mike re-dos.

2-10-0 Russian, brass model: fwd 2.0 oz .TE ; Rev, 2.3 oz.
4-8-2 USRA: plastic/metal: fwd 1.8 ; rev, 2.0
2-8-2 Mantua, cast Zamac: fwd 2.4 ; rev, 2.4

These numbers reflect the ability to pull approximately 25 to 35
free-rolling cars on level track, and seems about right for a 2-10-0 or
0-8-0 prototype, but way low for the mike and the mountain. Curiously, these
numbers are higher than expected "corrected" to scale numbers. I guess
model locos are asked to do more work in proportion to their prototypes due
to sharper curves and other factors so need to have more power relative to
thier size.

I know MR and other magazines have more sophisticated test set-ups, and
regularly publish new product's results, including TE (An example is an
On21/2 Porter 0-4-0T did 1 oz.and a Kato SD40 did 2.8oz) but this way I
can judge any inmprovements here at home, and so can you! I definitely plan
to add some lead to the Mikes as a result of these comparisons.

This was a fun little diversion, and I am interested to hear what results
other might get.

Keep steamin'
Tom K




Keeping the memory of steam alive!


Tom Knowles <ncstl@...>
 

.
High school physics suggests that TE for any model that can spin it's
drivers
is about 0.2 (coefficient of friction metal on metal) * weight on drivers.
The
diesels usually pull better than steamers which I attribute to more weight
and
all wheel drive so all weight is on the drivers, no unpowered pilot or
trailer
wheels. Seems to me you either add weight, or go with traction tires or
double
head...
The "straight & level track" is plenty good enough. It's the grades
down at
the club, we cross the Appalachians with better then 2% grade. As is, the
Pacific can get 7-8 cars over the ridge by itself. If I double head I can
do
about twice that....etc...

So, just weigh the engine, divide by 0.2. Any difference is the efficiency
of the mechanism of TE for that particular wheel-arrangement/loco. Delta TE
also equals delta 0.2 X weight, but weight is only part of the answer. I
think that part of the reason Diesels out-TE the steamers is the way the
diesel trucks allow the wheels to get better purchase on the rail-head. I
have a nicely matched A-B pair of Athearn F's with the super-power weights
and Northwest-shortline wheelsets.. This pair put out over 10oz. TE last
night! Hardly prototype in proportionto their scale. I need to weigh them
and do the co-efficiency math. To keep things fair, I'll probably pull the
weights out. The Mantuas are too much of a brick to do much with except add
weight, but I think I'll put in a set of NWSL "wimpy" springs in one of the
Decapods and re-measure it.

I think your Pacific is doing fine, and pretty close to prototype in
capacity--maybe 2 cars short. Our club has a 2% on a 36"R curve where mine
will only pull 4 cars. Admittedly it is a little slippery. I think mine's
problem is that the main driver is fractionally closer to the rails in the
frame than the other two, so never puts "all it's feet into it". How is
yours? This might be hard to correct, but I'll address that whenever I
re-wheel it with the spoked drivers I bought last year. I don't have a TE
report on it yet either.

I'll be making up a card file for each engine that lists statistics as well
as mods and maint. history. Soon, each one can be prototypically "called"
for the job at hand. My layout (unfinished) will have a ruling grade
(Cumberland Mountain-Cowan Hill pusher district) of 3% with a double-reverse
curve of 30"R.to the tunnel portal. This will be a tough pull and motive
power needs to be properly dispatched to keep the road open. Though we have
a couple of good club layouts here in the Triad, the plan is to operate mine
on "off" nights as a small group. There will be informality, but Boomers fit
in quicker when they have better info. Also, I sometimes forget myself what
will pull what.

Appalachians, eh? What club are you referring to?

Tom


Starr, David <david.starr@...>
 

Well, I got the ammeters mounted in the control panel last night. This
weekend I wind the shunts and get with it.
I think I'm going to measure tractive effort by simply adding cars to the
train until the locomotive can no longer move the train. I'll use 50' milk cars
with stock (plastic) wheels, no Reboxx ultra smooth rolling wheelsets. My cars
are all ballasted up to 4-5 oz. Test track to be my basement 4*8 oval with 18"
curves (no grades) , which is somewhat harder than "straight & level track".
This measurement technique is simple, and repeatable (for me). On the down
side, for someone else to duplicate the results, they would have to have a bunch
of similar cars.
If I have the energy, I might do all three of my steamers, the Pacific, a
Bachmann Consolidation and an IHC Mogul.

BTW. My club is the North Shore MRRC in Wakefield MA, not far from Rt 128.




David J. Starr
Senior Systems Video Engineer
Computer Products Division
781 937 1518
HTTP://www.analog.com/industry/video

----------
From: Tom Knowles[SMTP:ncstl@mindspring.com]
Reply To: HOsteam@egroups.com
Sent: Thursday, 17 August, 2000 12:19 AM
To: HOsteam@egroups.com
Subject: Re: [HOsteam] Actual "TE" test results

So, just weigh the engine, divide by 0.2. Any difference is the efficiency
of the mechanism of TE for that particular wheel-arrangement/loco. Delta TE
also equals delta 0.2 X weight, but weight is only part of the answer. I
think that part of the reason Diesels out-TE the steamers is the way the
diesel trucks allow the wheels to get better purchase on the rail-head. I
have a nicely matched A-B pair of Athearn F's with the super-power weights
and Northwest-shortline wheelsets.. This pair put out over 10oz. TE last
night! Hardly prototype in proportionto their scale. I need to weigh them
and do the co-efficiency math. To keep things fair, I'll probably pull the
weights out. The Mantuas are too much of a brick to do much with except add
weight, but I think I'll put in a set of NWSL "wimpy" springs in one of the
Decapods and re-measure it.

I think your Pacific is doing fine, and pretty close to prototype in
capacity--maybe 2 cars short. Our club has a 2% on a 36"R curve where mine
will only pull 4 cars. Admittedly it is a little slippery. I think mine's
problem is that the main driver is fractionally closer to the rails in the
frame than the other two, so never puts "all it's feet into it". How is
yours? This might be hard to correct, but I'll address that whenever I
re-wheel it with the spoked drivers I bought last year. I don't have a TE
report on it yet either.

I'll be making up a card file for each engine that lists statistics as well
as mods and maint. history. Soon, each one can be prototypically "called"
for the job at hand. My layout (unfinished) will have a ruling grade
(Cumberland Mountain-Cowan Hill pusher district) of 3% with a double-reverse
curve of 30"R.to the tunnel portal. This will be a tough pull and motive
power needs to be properly dispatched to keep the road open. Though we have
a couple of good club layouts here in the Triad, the plan is to operate mine
on "off" nights as a small group. There will be informality, but Boomers fit
in quicker when they have better info. Also, I sometimes forget myself what
will pull what.

Appalachians, eh? What club are you referring to?

Tom




Keeping the memory of steam alive!