Question on modern conventional engines

Well, I run only conventionally and generally whether I cycle the power down to zero or use the direction button, they cycle through the classic F-N-R cycle.  I have learned to bring power down to zero, period (throttle all the way back) or hold the direction button for a least a bit, in order to get the loco's attention.  

For the PS-3 MTH engine with speed control on you should be able to come in at a nice slow pace at 9-10 volts, well before the board tries to shutdown.

 

In general, conventional electronic reverse units respond quickly.  If voltage is held around 5-6 volts the unit may not move, but the reverse unit remains latched in the current direction.

 

Command engines run in conventional may have different responses depending on whether cruise is on or off, and any sort of momentum is set.   G

Sorry, I wasn’t referring to changing directions. I was speaking more about coming to a stop and then moving again in the same direction. Sometimes when bringing the engine to a stop the voltage is dropped too low and the train goes into shut down. I was just wondering if strictly conventional engines would do the same thing or if they are less sensitive to dropping the voltage a little too low.

I will have to look at how to use the speed control as well.

Most modern engines stop running (moving) at a voltage above zero.  The reason I stressed that I cycle all the way back to zero, or hit the direction button for a noticeable time, is that nearly going to zero does often not cycle the e-unit and so when I power up again the loco continues in the same direction.  I would think you would have to experiment with each loco to find out what works - the "minimum cycle voltage will probably be different with each loco.

You would want to be careful doing this.  Leaving the motor powered with insufficient voltage to turn motor can generate excess heat and ultimately damage the engine at some point. This is not easy to do with a conventional reverse unit.  G

I’m asking because I am currently running an MTH PS3 steamer conventionally and there isn’t too much of a margin between stopping the train completely and dropping the voltage sufficiently to put it into shut-down mode.  This makes it a little tricky to line it up to operating accessories where small adjustments forward or back are necessary.

 

Pontiac

 

MTH Proto 2 & 3 locomotives use a steady track voltage as a speed "command".  It takes a steady 8 volts to start a locomotive moving.  At 9 volts you are telling it to go 5 SMPH, 10 volts is 10 SMPH, 11 volts is 15 SMPH and 12 volts is 20 SMPH.  The 20 to 120 SMPH speed range us controlled by 12 to 16 volts.  The two part linear speed control was designed to give fine control on the low end of the speed range.

 

But, if you do not have precise voltage control you can't get precise speed control.  What kind of transformer are you using?  If it is an old post war transformer they tend to have high starting voltages and you may not have much range to work with between off and 8 volts. 

 

Pure conventional locomotives with modern can motors like those from Williams tend to take off like rockets at voltages that barely get command and sound equipped locomotives moving.

 

Thanks for the info. I'm using a Z1000. The speed control is fine. The engine will barely crawl if I want it to. I was just curious if conventional engines went into any type of shut down sequence if the voltage was dropped too low by mistake.

Not a sequence per se, but in my experience going "too low" on the voltage can unpredictably trip the E-unit (mechanical or electronic).

 

My WBB units will sometimes trip over into neutral, or even reverse direction completely when I try to feather the throttle and get down near zero.

Thanks