Help with controlling inline/decline speed (conventional)

[postwarpete]

I need some help if possible on controlling an incline that leads to a reverse loop.  The the train uses the same line up and down the incline and decline grade.   I understand I can do this with the some relays and diodes in line to increase and decrease voltage.   

I was wondering if I could use a dedicated 2 throttle transformer with trigger isolated rails at both the top and bottom to switch between each throttle one set for the incline and one set for the decline, understanding  I would make the incline an isolated block with each throttle soldered to the center rail of the incline and the outside rail to ground of the designated transformer.   I need some ideas on this and if it is feasible.   I figure having the dedicated dual throttle transformer would help tweak the voltage as needed depending on the trains and conditions for incline and decline.   

Lastly any ideas on wiring this with relays would be much appreciated.  Lastly any ideas if is it possible to use a 022 switch motor in place of a relay to switch between the preset throttles by attaching the isolated rails and separate throttles to each side of the switch machine?  Not sure on that but i know this has been done to wire and activate  dual animated accessories.  Much thanks for any ideas, help, or if I'm totally off base here.

thanks!

Pete

[TrainLarry]

Using insulated sections is the easiest way to get a different voltage to your inclined track. You would need a SPDT relay  to accomplish your task. You can use lockons in the insulated section; no need to solder wires to the track if you do not want to.

The 022 switch machines are not relays, and do not have heavy current carrying contacts. I have never heard of using these machines to operate accessories as you state. Perhaps a link to an application that does would be nice.

Larry

[postwarpete]

Thanks Larry,

What do you think of using the idea of a dedicated 2 throttle transformer instead of the diodes to set voltage for the incline and decline to that block? 

This shows using the switch motor to activate a 153 block signal.

https://www.youtube.com/watch?v=xGVUAhW77lM

thanks

Pete

Pete

[TrainLarry]

Thanks for the link. A very novel use of the switch machine, although I do not know if the contacts would withstand any heavy current switching, say for a motorized accessory. I see that the service manual for the signal mentions operation using an 022 switch, so it has been done; just never saw using the switch motor alone like in the video.

Using a dedicated transformer for your inclined track would be a very simple solution. Just make sure the transformer is properly phased to your main transformer, and you are good to go.

Larry

[lionelsoni]

Running across a block boundary between transformers set to different voltages is not a good idea.  Having the transformers in phase does not prevent the fault current that will flow when the pickups connect the two transformers together; it just makes it less spectacular.

The safest way to accomplish what you want is to switch the entire section, including the level track at each end of the incline, to whichever of the three voltages (up, down, or level) is appropriate for where the train is and which direction it is going.  This can be done with control rails and relays; but it is not a trivial problem, because the incline is traveled in both directions. Is the track long enough, or your trains short enough, that a train will fit entirely between the ends of the incline and entirely between the top of the incline and the middle of the reversing loop?

[postwarpete]

Thank you Bob for pointing out the roller jumping issue.  That makes perfect sense.   So my best solution is to read up on using relays and bridge rectifiers or diodes in series to reduce or increase voltage on the incline/decline with control rails at top and bottom and relays to activate the voltage increase and decrease as needed?   I'm aware of the theory but I've never done that so I need to do some research on the actual practice and configuration of this method.  If anyone has any links or ideas I would much appreciate it.  I need to be pointed in the right direction and decide if I can take that on or not.   I'm not an electrician or engineer...It sounds complex but If I can see or read about it I might be able to tackle it.

Thanks again.    

Pete

[TrainLarry]

If you want to save yourself a lot of work, get a ZW transformer with 4 throttles and use the 2 inner throttles for the incline. This way you do not have the problem of phasing transformers and fault currents between 2 different transformers.

Larry

[lionelsoni]

No.  Then you have the worse problem of fault currents within the same transformer.  You have only a fraction of the one transformer's output impedance to limit the current instead of the full output impedances of both transformers in series.  Furthermore, the fault current flows entirely within the secondary winding of the one transformer, avoiding the circuit breaker completely.

I have an idea for a relay circuit that may do the job.  I will write it up and post it when I have a chance.  It would use 3 relays and 4 control rails.  Two of the control rails need to be at least one train's length away from the incline in each direction.  Is that possible?

[TrainLarry]

It can be done with the ZW. I have 3 independent loops on my layout powered with a ZW. I do not have any issues when crossing over from one throttle/loop to another. What problem(s) should I be seeing?

Larry

[postwarpete]

Thank you Bob and Larry
I do have sufficient room above and below grade for the control rails to be one train length from grade. I would be willing to tackle the relay circuit but I am no expert at that type thing so I might need some guidance. The part of the layout is currently run off a late model cw 80. I have separated loops o42and o54 running on a kw but these are totally separated. I have an additional kw in storage. That doesn't matter crossing blocks from a cw 80 to a kw and back...still the risk of the the fault current right?
Thank you both again...I really appreciate your insights.
Pete

[lionelsoni]

If the open-circuit voltages are close enough to being the same, you won't see anything.  If they are different, there will be a current spike as each pickup set bridges the gap.  How much of a spike depends on the voltage difference, the transformer's output impedance, and your wiring and track resistance:  A greater voltage difference produces a greater current.  Greater impedance and resistance produce less current.  As the short circuit caused by each pickup set clears the gap, the inductive component of the transformer's output impedance may produce a voltage spike, possibly in the hundreds of volts.  Traditional trains will probably shrug this off; but modern electronics-heavy trains may be vulnerable.

Note that for level running, unless you make a mistake, it is likely that you will set the voltages to nearly the same value.  Using the multiple transformer outputs to regulate speed going up and down a hill implies that you are deliberately setting the voltages to different values.

If the train should stop for some reason with the pickups bridging the gap, the transformer and wiring (both between the transformer and the track and between pickups on the train) may be damaged by an overcurrent that will not trip the circuit breaker.

[lionelsoni]

Here it is.  This is a detached-contact telephone-style schematic, which is easier to make with ASCII.  The relay contacts are X for normally open and | for normally closed.  Each contact is labeled with the name of the relay that operates it.

There is a T(op) relay and a B(ottom) relay.  Each one is operated when the train reaches the control rail located at its end of the incline.  A normally-open contact on the relay latches it, so that it remains operated after the train has passed.  When the train gets far from the incline, relay R(elase) interrupts current to both relays to release them to be ready for the next transit of the train.

                      control rail
            -----   o far from
relay       |   |   | top of incline
supply------| R |---|
voltage  |  |   |   | control rail
         |  -----   o far from
         |            bottom of incline
         |
         |        -----
         |        |   |     T
         |     ---| T |-----X---common
         |     |  |   |  |
         |     |  -----  | control rail
         |  R  |         o at top of
         ---|--|           incline
               |  -----
               |  |   |     B
               ---| B |-----X---common
                  |   |  |
                  -----  | control rail
                         o at bottom of
                           incline

There is a contact tree on the T and B relays that connects the center rail of the entire division to the normal level-running layout track voltage whenever both T and B are released at the same time or both operated at the same time.  When only one of T or B is operated, the tree selects the low or high track voltage respectively.

                  T      high
               ---|------track
            B  |         voltage
         ---X--|
         |     |  T
         |     ---X---
center   |           |   medium
rail-----|           |---track
         |        T  |   voltage
         |     ---|---
         |  B  |
         ---|--|
               |  T      low
               ---X------track
                         voltage

The relays can have AC or DC coils, with the appropriate matching power supply.  Or you can use DC relays with an AC supply by putting an individual bridge rectifier upstream of each coil. 

[postwarpete]

Thank you very much Bob for all your time and help...I truly appreciate it.  I will be collecting the components to tackle this in the next week.

Kind regards, 

Pete

[postwarpete]

Hello Bob if  you read this I need some clarification if possible:

 At the top right hand side of the first schematic for the R relay where it connects to the control rails far from top and bottom  I'm, not clear on that connection to  relay R form the distant control rails?  Not sure what that stood for or where or how exactly that connect to relay R ?  Thanks  

Pete 

[lionelsoni]

One of the coil terminals of relay R connects to the relay supply voltage (which has a return to the outside-rail common).  Both of the far control rails and the other coil terminal of relay R are all three connected together, in any convenient fashion.  The idea is that when the train passes over either of the far control rails, relay R releases both of the other two relays, making them ready to detect the next train arriving at the incline and to set the center-rail voltage for the entire mountain division appropriately for that train's direction, whether up or down.

[postwarpete]

okay thanks again...much appreciated!