Model Railroading > How do you like to control helper engines?

In order to power a long train, many times a set of helper engines is used.  I've observed the following methods:

1)  Buddy System
One engineer controls the head-end power with a throttle.  Another engineer controls the helpers with a different throttle.  The head-end and helpers have separate Consist Assignments.  The engineers must be in constant contact to coordinate their speeds.  

2)  Solo
The engineer has all engines in the train Speed Matched EXACTLY, so they all can be in the same Consist Assignment in the throttle.  The speed for BOTH the head-end and helpers are changed simultaneously by a single throttle.
 
3)  Total Recall
The head-end power and helpers have separate Consist Assignments, on a single throttle.  A single engineer uses the RECALL button on the throttle to toggle between the head-end and helpers.  The Speed Steps are incremented (or decremented) by small amounts each time the speed is changed, in order to prevent the speeds from getting too far out of sync. 

Yesterday I used the Buddy System, to run The Oil Cans on the La Mesa Layout (at the Balboa Park Musenum, San Diego, CA).  All 8 engines were Speed Matched (using the 28 Step Method) to each other.  4 on the head-end and 4 mid-train helpers.  I was running the helpers.  The head-end engineer, Henry, would tell me what Speed Step he was on, and I would immediately match it.  We left the SP Bakersfield Yard, heading Eastward (uphill), thru Caliente, Walong, and Tehachapi Summit.  The run was flawless, with no derailments along the way.  I constantly observed the coupler slack, which was fine the whole way.  In theory, with all engines Speed Matched, next time I could run The Oil Cans with the Solo method.  

This run answered a few questions for me.

1) 8 engines is sufficient power to run a 60-car train.
2) 8 engines (all having sound), under load, will not trip the 5A DCC Booster. 
3)  I was considering adding extra weight for better tracking.  However, the stock weight (5.1 oz.) of the Oil Cans cars appears to be sufficient.   (The NMRA guidelines suggests (1 + 8/2 = ) 5 oz for the 8" length of the Oil Cans cars.)
4) Mid-train helpers are not necessary for the down-hill (Westward) trip.  4 engines would probably work, but 6 would be more prototypical for the "empties" making their way back to Bakersfield for a refill.

Thank you in advance for sharing your experiences with running helper engines.  :-)
Dave


Dave



Edited 10 time(s). Last edit at 07/23/25 16:00 by tmotor.

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Man that is an awesome looking train! Sure brings back memories of watching the cans on Tehachapi, those were the days.

My layout is too small and too flat for helpers. Personally, I like the buddy system as it is more prototypical. If I had a helper district, I would want the option to be able to operate solo with everything fully speed matched, seems safer for me.

Nathan

Posted from iPhone

Greetings Nathan!

> Man that is an awesome looking train! Sure
> brings back memories of watching the cans on
> Tehachapi, those were the days.
Indeed!  
No matter how slow the traffic was on Tehachapi, we could always count on The Oil Cans making its daily run in the afternoon.  :-D

> My layout is too small and too flat for helpers.
Ditto, which is why I had to join La Mesa.

> Personally, I like the buddy system as it is more
> prototypical.
Back in the day, I do remember hearing the engineers talk to each other on the scanner.  The head-end engineer would let the helper crew know the non-green color of signals ahead, so they would know to expect to slow-down.  

If I had a helper district, I would
> want the option to be able to operate solo with
> everything fully speed matched, seems safer for
> me.
Agreed.
There were some times when the head-end engineer was around a corner, or out of sight.  If a derailment occured and I wanted to stop the train immediately, it was sketchy.  Hopefully the engineer had his throttle plugged-in and could respond immediately to my shout of STOP-STOP-STOP!  If he was in the process of moving to the next plug, then there would be a delay for him to plug-in, establish a connection to the Command Station, and then Stop.  This delay is more than enough time for the stopped helpers to be an anchor that the head-end is pulling against.  Unless the train is on a straight section of track (rare), the cars in-between the helper and head-end will string-line on a curve.  (Guess how I know this...)  This is exacerbated by the double-shelf couplers, which will NOT uncouple in a derailment.  Instead, the domino-effect will apply.  NOT pretty!  If I'm running with the Solo method, then there is no risk of a communication issue.

Take are and God bless!
Dave



Edited 7 time(s). Last edit at 07/25/25 04:29 by tmotor.

Nice subject & one that I've been meaning to ask.
Both ways but have you turned off Back EMF? 
In my limited use of DPUs & several spectacular derailments on two layout with grades. My experience when using advanced conststing was what appeared to be the helpers/DPUs speeding up when starting up a grade. Friends that had speed matched the locos had the same issues.
My engines were stock Scaletrains Dash 9s (5 & run 3X2) that all ran close to the same but not speed matched. I had only changed acceleration to 40 & stopping to 0. The train was 30 LBF 5160 hoppers with stock weight.
When I turned off Back EMF (Not the group) all was fixed when running Helpers or DPUs. I have run a 70 car grain train with DPUs this way.
My understanding of Back EMF is its like cruse control in our autos. When going up a hill it applies more power to maintain speed & less power when going down. This is good & bad. When running all engines in a consist coupled together it is good but when engine are separated it can be bad.
When "Back EMF" is turned off the engines run like on DC with full control of power. 
As much as I like heavy cars I am not sure they are necessary but it is important to have all about the same weight. This come from have we ever seen a heavy car derail? No, only light one. I run some cars with no weight at the back of trains. My trains are 16 Auto racks to 30 freight cars. It is more important to have engines responding the same front & rear unlike the semi automatic speed control with "Back EMF" on. 
At this time I have not tried this with Soundtraxxs, Only with ESU but don't see why it wouldn't work with them.
I am not a expert on DCC & I don't care for it. I run mostly unit trains which is why I'm not a fan of DCC.
Here is a link that helped me understand what was happening. 

https://dccwiki.com/Back_EMF 

I hope other with more experience then me on DCC will add to this.

Tim Hanesworth
Santa Rosa, CA

From what I've seen in the past there needs to be plenty of cars and watch the slack point, also called the bunch or the node, to prevent tension in the train also reffered to as string lining on curves.

People tend to run unit trains or repeating a successful train over and over, which works but can get stale. The two operator methid seems to be the simplest and also allows the helpers to be returned to a terminal or whatever as another operating move to add interest. Regardless, running helpers is an acheivement and shows a well running layout, cars and locomotives. Congrats.

+ not to suggest running the Cans or the Costa Mesa Layout can be considerd stale.



Edited 1 time(s). Last edit at 07/23/25 07:45 by TCnR.

tmotor Wrote:
-------------------------------------------------------
> > My layout is too small and too flat for helpers.
> Ditto, which is why I had to join La Mesa.
>
> Take are and God bless!
> Dave

Dave, you are blessed to have that awsome club within driving distance.  I'm in northern Virginia so no idea when I would be able to get out to see the layout some day.  Since I only watched SP trains in the Davis / Sacramento area back in the 70's and 80's I never got to see the oil cans run.  Your train looks great! - If you have any videos on Youtube, please provide the link.

My layout is about 15x33 feet with passing sidings 21 feet long, which isn't bad for a home layout but still too small for really long trains.  The physically longest train I've run so far is the D&RGW/UP Kaiser CoaI Liner train with 35 hi-side gondolas.  I do have a helix with a 1.7%  grade and a 1.8% max grade on the mainline "nolix" portion. I suppose I could run helpers.  I tried pulling 36 PFE ice reefers up that 1.7 grade helix with my Intermountain SP cab Forward, but the drivers slipped so a helper would be needed there, or a shorter train.  The train in the attached photo has 30 ExactRail Rio Grande quad hoppers and four diesels and just fits in the siding.

I do have the large logo Genesis Tank Train cars to run - and need to get them on the layout!

Cheers,
Jim
 

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Greetings Tim!

> Nice subject & one that I've been meaning to ask.
> Both ways but have you turned off Back EMF? 
Yes.
When the engines were Speed Matched, the Back EMF was disabled.  When running them on the layout, it was kept off so there was one less possibility for an issue.
That said, I do like Back EMF.  In the future I may enable it to see if it makes a difference.  For now, having a high (powered) axle-to-car-ratio is key.  ScaleTrains engines are HEAVY, and good pullers.  The recommended ratio is 1 powered axle for 2 cars (40'ers) being pulled.  60 cars would be (60/2 - ) 30 axles.  For 8 6-axle Tunnel Motors, that is (8x6 = ) 48 axles of power.  Granted, the Oil Can cars are longer than 40' so they weigh a bit more.  Even so, with 8 engines, there is power to spare.  This helps maintain the proper slack action.  In this scenario, as long as both the head-end and helpers respond the same, enabling Back EMF should (in theory) be fine.  However, since I have had success with Back EMF disabled, there's not much reason to enable it (other than curiosity).

> In my limited use of DP Us & several spectacular
> derailments on two layout with grades. My
> experience when using advanced consisting was what
> appeared to be the helpers/DPUs speeding up when
> starting up a grade.  Friends that had speed
> matched the locos had the same issues.
Yikes!
That could take all the slack out, and shove against the head-end.  :-O

> My engines were stock Scaletrains Dash 9s (5 & run
> 3X2) that all ran close to the same but not speed
> matched. I had only changed acceleration to 40 &
> stopping to 0. The train was 30 LBF 5160 hoppers
> with stock weight.
> When I turned off Back EMF (Not the group) all was
> fixed when running Helpers or DPUs. I have run a
> 70 car grain train with DPUs this way.
Good to know.

> My understanding of Back EMF is its like cruse
> control in our autos. When going up a hill it
> applies more power to maintain speed & less power
> when going down.
Correct.
The decoder adjusts power to maintain speed.

> This is good & bad. When running
> all engines in a consist coupled together it is
> good but when engine are separated it can be bad.
> When "Back EMF" is turned off the engines run like
> on DC with full control of power. 
Yikes!

> As much as I like heavy cars I am not sure they
> are necessary but it is important to have all
> about the same weight. This come from have we ever
> seen a heavy car derail? No, only light one. I run
> some cars with no weight at the back of trains. My
> trains are 16 Auto racks to 30 freight cars. It is
> more important to have engines responding the same
> front & rear
Agreed.
That is the key.  
I like the degree of control given with the 28-Step method of Speed Matching.  (I plan to post my observations of the process in the near future.)

> unlike the semi automatic speed
> control with "Back EMF" on. 
> At this time I have not tried this with
> Soundtraxxs, Only with ESU but don't see why it
> wouldn't work with them.
> I am not a expert on DCC & I don't care for it. I
> run mostly unit trains which is why I'm not a fan
> of DCC.
Things in the DCC world can get complicated, I get that.  Just starting with a few CVs (Control Variables) and trying some features helps appreciate the rich functionality that is possible.  
Using software/hardware like LokProgrammer helps provide a better interface, but still takes time to understand. 

> Here is a link that helped me understand what was
> happening. 
>
> https://dccwiki.com/Back_EMF 
Thanks for sharing the link.

> I hope other with more experience then me on DCC
> will add to this.
Indeed!

Take care and God bless!
Dave



Edited 2 time(s). Last edit at 07/25/25 04:35 by tmotor.

The only comment I have regarding the original post is this. I run multiple units at head-end, mid-train or end of train. I have found that if all units have the sound "on" it tends to blend into a white noise. You can't hear the details in the sound and it can be annoying rather than realistic. I have found a better effect is to have only one engine with the sound activated in each group of locomotives. So a train with mid and rear helpers would only have three locomotves with sound activated. You get to hear the sound as each group passes without the white noise.

This is a little off topic but you may wish to try it. Great question to post and many thought provoking replies!



Edited 1 time(s). Last edit at 07/23/25 11:54 by pilotblue.

Very nice!  I've used the Solo method quite a few times with my Southern Railway mid-train helpers with the entire consist being ScaleTrains SD40-2s and SD45s perfectly speed matched.  A critical element is silk smooth track and power transitions speed wise, along with keeping it in the 35-40MPH scale speed range.  .  

Here is an example.  This was filed a couple years ago on my previous layout and before the additions of the great Southern Caboose models from Tangent.

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the digitrax 602 throttle has two controls, so the left controls the head end and the helpers on the right. 

it's great because the throttles activate when the control knob for that side is turned, no need to switch sides to modify the loco speed, just turn the knob

Back in my DC days when speed matching wasn't possible, I would just put a helper set 2/3rds back in the train and normally would place the faster locomotives there. They would push several cars ahead of them until the weight balanced the speed with the head end power. It was fun to watch the floating couplers go back n forth through the cars ahead of the helpers. It works much the same way with DCC. The trick is to have a heavy enough train where the helpers have enough weight both behind and ahead that the they self balance. You do not want that floating coupler point to be tugging at the front of the helper set, nor having the helpers pushing everything into the head end units. Both situations are asking for trouble.

Ted Curphey
Ontario, OR

The right way I believe to do it for a 70s modeler is to have two engineers, one on the head end and the other running the helpers. We ran 64 beet racks with a tail pusher behind the caboose at LaMesa. The key is good running locomotives that are speed matched and communication between engineers on throttle settings. Of course good clean track is essential. We also had TCS wireless throttles and didn't have to plug in. Not sure why more members at LaMesa haven't adopted them. Not having to plug in is fantastic. A club member shot video of the train. Hope this link works.
https://onedrive.live.com/?redeem=aHR0cHM6Ly8xZHJ2Lm1zL3UvcyFBdk9kMGZqc1BjTlhoTEpXTTBMNmtONTVPVXNoV1E%5FZT1NZW9mN3k&cid=57C33DECF8D19DF3&id=57C33DECF8D19DF3%2172035&parId=57C33DECF8D19DF3%2172022&o=OneUp

Greetings TCnR!

> From what I've seen in the past there needs to be
> plenty of cars and watch the slack point, also
> called the bunch or the node, to prevent tension
> in the train also reffered to as string lining on
> curves.
Constantly maintaining the slack ahead of the helpers is key!
While traveling downhill, Henry thought it would be a good idea to stretch-out the slack.  As he went up one notch, he told me what he was attempting to do.  Before I could say anything, the cars had string-lined the horseshoe curve between Tunnel 5 and 4.  :-O
The good news is this part of the layout is not easily seen by the public.  The bad news is access to the track in this area is limited.  It took several minutes to rerail the cars.  (Those double-shelf couplers really do work, even in miniature!)  
This would have been a non-issue if the helpers were not in-play.  On a downhill train, there is no need for helpers.  In the future, I will seriously consider not running helper when Westbound.  One less reason for a derailment.

> People tend to run unit trains or repeating a
> successful train over and over, which works but
> can get stale.
I plan to have a few different trains and will run them based on the amount of traffic.  If it is crowded, I will run a clearing train (short enough to fit in all of the sidings), such as the Coil CARE unit train.  It is a very heavy train, so can justify lots of power on a short train.  I can also run fewer cars of (normally) non-clearing trainsets, such as a UPS Hotshot, or a JB Hunt consist.  However, if I'm allowed to run a monster train, that is my preference.  I need to be able to look several blocks ahead to confirm on-coming traffic will clear the next siding, and coordinate with the engineer.  I will hold the main, line the turnout for the on-coming train to take the siding, and wait for the train to arrive.  The price of running a non-clearing train is playing the waiting game, but it is worth it!  I noticed that when the opposing train is taking the siding, that is when the public takes their cellphones out to shoot images or video.  

> The two operator methid seems to be
> the simplest and also allows the helpers to be
> returned to a terminal or whatever as another
> operating move to add interest.
True.  If the helpers are to be cut-in or cut-out, that is a good option.

> Regardless,
> running helpers is an acheivement and shows a well
> running layout, cars and locomotives. Congrats.
Thank you for the positive feedback!  :-D
Indeed, there is more than just adjusting the throttle speed to keep "the shiney side up and the dirty side down".  
The previous week, I spent about 18 hours Speed Matching the 8 engines.  This allowed the throttles to be set and basically left as is for the entire uphill climb.  The casual observer might say, "How hard can that be?"  But to those that have attempted to run helpers, they know there is alot that can go wrong.  To achieve a derailment-free trip, it takes time (behind the scenes), skill, and a bit of luck. 

> + not to suggest running the Cans or the Costa
> Mesa Layout can be considered stale.
LOL!
If someone sees me running the exact same train each time, it is easy to conclude I would get bored.  However, there would be something different each time it ran.  Perhaps I changed a sound file in one of the engines, or weathered some of the cars.  Each time, the train would be a little closer to "done".  Running it validates the changes, and brings a sense of pride.  I find the fastest way to engage with a member is to make a positive comment about the engines they are running (such as a weathering job) or their choice of cars. 

Take care and God bless!
Dave

Greetings Jim!

> Dave, you are blessed to have that awsome club
> within driving distance. 
indeed!  The 5 hours (one way) trip on Amtrak to get there used to be a deal-breaker for me.  Now I know it is worth it.  Plus, time goes pretty quickly when I'm on a laptop.  I envy the members that live a few miles away, but moving to San Diego is not an option for me.  (It would be a tough sell to my wife.   :-O  )

> I'm in northern
> Virginia so no idea when I would be able to get
> out to see the layout some day.  Since I only
> watched SP trains in the Davis / Sacramento area
> back in the 70's and 80's I never got to see the
> oil cans run. 
The Oil Cans made quite an impression on me.  I must not be the only one.  There are several members that have their own set of Oil Cans cars as well.  If two are running in opposite directions, this is an issue as both are non-clearing trains.  One of them needs to be separated at the helpers and parked in separate sidings, in order to allow the other to pass.   

> Your train looks great! - If you
> have any videos on Youtube, please provide the
> link.
Thank you for the positive feedback!  :-D
Believe it or not, this was my first time running helpers.  I didn't have time to shoot video, but only time to take a couple of grab shots to document the run.  I spent most of my time monitoring the slack ahead of the helpers.  The cool thing is I didn't have to touch the throttle settings.
As I gain more confidence, I will spend the time to set-up my cellphone and/or GoPro to record some roll-bys.

> My layout is about 15x33 feet with passing sidings
> 21 feet long,
NICE!  :-D
I wish I had the room for a layout of that size.  

> which isn't bad for a home layout
> but still too small for really long trains.  The
> physically longest train I've run so far is the
> D&RGW/UP Kaiser CoaI Liner train with 35 hi-side
> gondolas.  I do have a helix with a 1.7%  grade
> and a 1.8% max grade on the mainline "nolix"
> portion. I suppose I could run helpers.  I tried
> pulling 36 PFE ice reefers up that 1.7 grade helix
> with my Intermountain SP cab Forward, but the
> drivers slipped so a helper would be needed there,
> or a shorter train.  The train in the attached
> photo has 30 ExactRail Rio Grande quad hoppers and
> four diesels and just fits in the siding.
Gotta' LOVE the Quad Hoppers!

> I do have the large logo Genesis Tank Train cars
> to run - and need to get them on the layout!
The Tank Train logo is pretty cool.  
The ones with the bold orange & white Tank Train logo were run before I started railfanning Tehachapi.  However, I did see a single Oil Can car in the SP Bakersfield Yard with the bold logo peeking-thru the fading black paint-over job.  The connector hose was stowed in the hose rack.  I assume the car was enroute to be a replacement for a car sent for service. 

Take care and God bless!
Dave



Edited 2 time(s). Last edit at 07/25/25 04:44 by tmotor.

I have a six lap helix on my layout and use a helper to move trains up the hill.
I think having one operator on the head end and another on the pusher is
more of a challenge, and hence more fun, and speed matching engines is not
important between the front and the rear.  Skill is the only thing that really matters.

That said,I model the 1950s, so a manned helper would be the norm.

just for additional thought the guys at the BNSF Fall River Sub Layout run a rear pusher helper with the front knuckle removed. That improves the chances of not derailing and also lets them simulate the prototype practice of cutting off on the fly.

Not the same as mid-trains but another approach mostly for the operations side of things.

+Here's another interesting modeling the cans post:

Date: 08/23/22 14:08
Started weathering the tanktrain
Author: bnsfmodeler

https://www.trainorders.com/discussion/read.php?3,5529465,5529484#5529484

 



Edited 1 time(s). Last edit at 07/24/25 08:46 by TCnR.

I wish my layout space was bigger but it's the best I could do in the west Washington DC surburbs.  I grew up in northern California and I think I've only seen one basement ever and that was in Sacramento. So unless you have an outbuilding or convert a 2 car garage into a layout room, I guess a club would be needed. In not too many years hence, I will be retiring and moving so I'll be hunting for a house with layout space in a lower cost of living area - not sure where yet.  Cost of living in California is too high so that's off the list.

tmotor Wrote:
-------------------------------------------------------
> Gotta' LOVE the Quad Hoppers!

Being a Rio Grande fan since the 80's, I always wanted a fleet of the Behlehem quads.  I picked up all 3 sets of the Walthers 6-pack kits and additional ones later.  Then in 2013, Exactrail announced their first run of Rio Grande quads in the 12xxx number series and 48 numbers.  At the time money was tight and I was only able to order 6 before the entire run sold out in maybe a weeks time.Since then I manages to purchase the 1st run of the 16xxx series and got 23 of the 24 numbers.  The last batch to come out were two batches of 18 each in the 19xxx and 16xxx series and a grabbed them all.  All total I think I have 65 now.  They are a little light but do run.  With helpers, the would surely need extra weight.

I am mainly interested in caboose era D&RGW so pre-1985.

Cheers.
Jim

 

Greetings pilotblue!

> The only comment I have regarding the original
> post is this. I run multiple units at head-end,
> mid-train or end of train. I have found that if
> all units have the sound "on" it tends to blend
> into a white noise. You can't hear the details in
> the sound and it can be annoying rather than
> realistic.
Guilty as charged.
All of the Tunnel Motors have LokSound decoders and are running stock sound files.  They do tend to blend into one sorta' monotone roar.  
The next project is to use LokSound to adjust the sound for each engine to make them unique.  So instead of them sounding like a choir of just tenors, the full range of octaves is present, producing a more realistic chorus.

> I have found a better effect is to have
> only one engine with the sound activated in each
> group of locomotives. So a train with mid and rear
> helpers would only have three locomotives with
> sound activated. You get to hear the sound as each
> group passes without the white noise.
That would solve the issue.
One obnoxious issue on my run is, somehow F17 (apply hand brake to tie-down the engine) was enabled in the decoder template file.  After an engine was warmed-up, that file was loaded as a starting point for Speed Matching.  F17 is set to be ON randomly, so it doesn't occur very often.  I rarely heard it when performing Speed Matching.  However, when running them on La Mesa, at least one of the 8 engines played the F17 sequence, and it was LOUD.  :-O   
I couldn't remember which function key controlled the offending sound track, and the chart was in the box in another room.  We decided to press on and deal with it later. 
One of the reasons I didn't shoot video is because this unrealistic sound would randomly interrupt the otherwise prototypical performance.   
After the downhill run, we parked in the SP Bakersfield Yard, then went to lunch.  After returning, I dug-out the chart to track-down F17.  I disabled F17 in each engine in the helper set.  However, Henry wanted to attack The Hill ASAP and was not as bothered by F17, so he left it enabled on the head-end. 
Note (1) to self: Take a picture of the chart in the ScaleTrains documentation and keep in on my cell phone, just in case an unwanted function creeps-in.
Note (2) to self: Crank the sound WAY down on F17, or remove it from the decoder's Function Key Mapping chart (since I never use it). 

> This is a little off topic but you may wish to try
> it. Great question to post and many thought
> provoking replies!
The TrainOrders community is a wealth of information.  :-)

Take care and God bless!
Dave
 

Greetings RailThunder!

> Very nice!  I've used the Solo method quite a few
> times with my Southern Railway mid-train helpers
> with the entire consist being ScaleTrains SD40-2s
> and SD45s perfectly speed matched.  A critical
> element is silk smooth track and power transitions
> speed wise, along with keeping it in the 35-40MPH
> scale speed range.  .  
Very smooth mid-train helper performance!
Definitely a testament to your Speed Matching skills.  Nicely done!  :-D
Needless to say, smooth trackwork is a must.  Nothing spoils the realism of an Op Session like a derailment.  :-(

Take care and God bless!
Dave