Best way to control jack rabbit starts?

Option "C", what transformer are you using?

 Many locomotives that don't have much or any electronics in them will "Jackrabbit" when used with transformers that have a high minimum starting voltage

The much maligned (not justifiably, in my opinion) Lionel CW-80 is a Great transformer for seeing just how slow and smooooth a start an locomotive is capable of. The CW-80 has a near zero minimum starting voltage, that can make many former jackrabbits, Wonderful slow speed performers.

 Many Post War transformers have a starting voltage in 5-7 volt range, that can launch DC can motored locomotives.

Doug

I use both a ZW and a CW-80, and you are certainly correct - the ZW does tend to launch engines rather than start them. The CW starts fairly slow (making a slight buzzing sound, I suppose from the chopped waveform). I would like to be able to run this (2030) engine and a Williams Geep that does the same thing, on both transformers, so I will modify both - just looking for some experienced observations on which way might be better.

There is a discussion here: discussion on slowing starts

In addition to 1 and 2 above, I add thermistors into the circuit in series with the diodes.   The thermistor gradually allows more current to pass as it warms up.

GeoPeg posted:

Method 1: Wire the 2 motors in series with one another instead of parallel. I'm guessing this is simply lowering the voltage by roughly half on each motor. I tried this on the test bench and immediately noticed a reduction in start up speed...seems to work. But I also noticed that one motor always runs a bit faster than the other when freewheeling. If I slow the wheels on one motor with my fingers, the other motor speeds up - and vice versa. So it appears at least, to be self regulating. I would think the motors need to be fairly closely matched to wire them is series, and if not, one will always be doing the work ... not a good scenario.

This is a non-issue in the real world when it's on the tracks.  When freewheeling, any slight difference in friction in the gear train will cause one to run faster.  On the tracks, any small differences are swamped by the fact that the wheels are driving.

As far as matching the motors, the motors should be identical in virtually any engine with dual motors.

Pay attention to Dale H.'s comment about the heat of the diodes and the plastic frame of the Alco if you use them.

A little expensive but one can adjust TMCC in Conv. to custom adjust locomotives.

Geopeg, there is one other option and that is using the Lionel 1033 transformer. I run a variety of locomotives, all non-command, both postwar and the 1990's vintage type like your K-Line MP-15 with dual DC motors mounted in the trucks.

While many modern transformers have a lower starting voltage (as with the CW80 like you mentioned), the high end voltage of those transformers will likely cause your train to go flying off the track on curves.

Despite the many choices of transformers, the 1033 has remained my favorite. The 1033 transformers are readily available, affordable and easily serviced... which is a good thing to do if you a buying them used... at least have them checked. I've been using them for many, many years with no complaints.

There are two choices of voltage post settings to the track...

1) The A-U setting puts 5-16 volts to the track, which is perfect for postwar/MPC locomotives with AC open frame motors. This setting is also good for the RMT S-4 and RDC Buddy, which have different spec motors from their predecessor K-Line versions and need the higher voltage.

2) The B-U setting puts 0-11 volts to the track, which is perfect for the truck mounted DC can motored engines. They don't start running like jack-rabbits, and the lower high-end voltage reduces the risk of them flying off the track on curves.

Another "multi-control" transformer in addition to the 1033, is the Lionel KW, which gives you the choice of either 6-20 volts or 0-14 volts to the track. It is worth noting with the KW and the 1033, that your choice of voltage to the track, alters the secondary voltage post options for accessories. Since I use other transformers for accessories and lights - which gives me the freedom of fine tuning voltage for those accessories, this is not a concern for me.

As you mentioned, you can wire the motors in series, but this does reduce the pulling power of the locomotive.

One more unsolicited tip. These dual DC truck mounted motored locomotives have a nickname of "growlers" because they tend to make a growling sound when going around tight 027 curves. K-Line not always, but usually had the traction tires placed diagonally on the same motored truck: One on the left of one axle and the other on the right of the axle on the same truck. I remove one of those traction tires from each truck. I haven't experienced any significant loss of traction, but the growling noise is definitely reduced. I do add a little more weight though, to the engines. And since these diesel locomotives have a occasional tendency to jump the track (depending on your layout set-up), I have inserted a small spring between the top of the front motor truck and the bottom of the sheet metal frame. There is a guide pin on the top of the motor truck that goes into a curve slit in the frame... I put the spring over this pin, and the derailment issue disappeared completely.

Good luck in whatever method you chose to pursue.

brianel_k-lineguy posted:

Geopeg, there is one other option and that is using the Lionel 1033 transformer. I run a variety of locomotives, all non-command, both postwar and the 1990's vintage type like your K-Line MP-15 with dual DC motors mounted in the trucks.

While many modern transformers have a lower starting voltage (as with the CW80 like you mentioned), the high end voltage of those transformers will likely cause your train to go flying off the track on curves.

Despite the many choices of transformers, the 1033 has remained my favorite. The 1033 transformers are readily available, affordable and easily serviced... which is a good thing to do if you a buying them used... at least have them checked. I've been using them for many, many years with no complaints.

There are two choices of voltage post settings to the track...

1) The A-U setting puts 5-16 volts to the track, which is perfect for postwar/MPC locomotives with AC open frame motors. This setting is also good for the RMT S-4 and RDC Buddy, which have different spec motors from their predecessor K-Line versions and need the higher voltage.

2) The B-U setting puts 0-11 volts to the track, which is perfect for the truck mounted DC can motored engines. They don't start running like jack-rabbits, and the lower high-end voltage reduces the risk of them flying off the track on curves.

Another "multi-control" transformer in addition to the 1033, is the Lionel KW, which gives you the choice of either 6-20 volts or 0-14 volts to the track. It is worth noting with the KW and the 1033, that your choice of voltage to the track, alters the secondary voltage post options for accessories. Since I use other transformers for accessories and lights - which gives me the freedom of fine tuning voltage for those accessories, this is not a concern for me.

As you mentioned, you can wire the motors in series, but this does reduce the pulling power of the locomotive.

One more unsolicited tip. These dual DC truck mounted motored locomotives have a nickname of "growlers" because they tend to make a growling sound when going around tight 027 curves. K-Line not always, but usually had the traction tires placed diagonally on the same motored truck: One on the left of one axle and the other on the right of the axle on the same truck. I remove one of those traction tires from each truck. I haven't experienced any significant loss of traction, but the growling noise is definitely reduced. I do add a little more weight though, to the engines. And since these diesel locomotives have a occasional tendency to jump the track (depending on your layout set-up), I have inserted a small spring between the top of the front motor truck and the bottom of the sheet metal frame. There is a guide pin on the top of the motor truck that goes into a curve slit in the frame... I put the spring over this pin, and the derailment issue disappeared completely.

 

Good luck in whatever method you chose to pursue.

I recommend the same. I have a MP-15 and had to add weight over the front truck. It's been fine since.

If you go the diode route per Dale's link above, note he references using a bridge which is 4 diodes in a package.  This can reduce soldering.  Additionally, most bridges 6 Amps and up have mounting holes which can assist with heat-management as they can be more readily attached to, say, a steel chassis if there's room.  The cylindrical shape of the loose diodes provides flexibility in orientation but more difficult to attach if you need to draw away the heat from the component.  Here are 4 individual 6 Amp diodes vs. 8 Amp bridge and example of 8 Amp bridges mounted to a metal heat sink.

Ken-Oscale posted:

There is a discussion here: discussion on slowing starts

In addition to 1 and 2 above, I add thermistors into the circuit in series with the diodes.   The thermistor gradually allows more current to pass as it warms up.

On single motored Williams I just use a single thermistor buts its a specific type called a current inrush limiter. They come in different resistance and current ratings. The one I use is a STM (brand) CL-160. It has a resistance at 70F of 5 ohms and at 2.8 amps the resistance becomes zero. 5 ohms is close to the DC resistance of the ubiquitous Mabuchi RS385 motor used in the majority of two motored diesels and single motors traditional steam engines. At start it cuts the voltage at the motor about in half. As it speeds up the motor receives a greater portion of the track voltage so full speed is close to the same. Use one on each motor in two motored diesels.

I have run this engine on a parallel track with an MTH PS2 engine next to it. Using a 1033 transformer it will run at the same speed (running light) as the MTH engine running 3 MPH.

Pete 

Probably a good idea to specify whether you are using a positive or negative thermistor in the comments as well.

Why are you making this complicated and adding parts?  If the series motor connection works, all it takes is a couple solder joints, no diodes, no thermistors, etc.

aussteve posted:

Probably a good idea to specify whether you are using a positive or negative thermistor in the comments as well.

Current InRush Limiters have by definition a negative temperature coefficient. For those not familiar with the term, that means the resistance decreases when the temperature increases.

Pete

gunrunnerjohn posted:

Why are you making this complicated and adding parts?  If the series motor connection works, all it takes is a couple solder joints, no diodes, no thermistors, etc.

How do you wire a single motor in series?

Pete

Norton posted:

gunrunnerjohn posted:

Why are you making this complicated and adding parts?  If the series motor connection works, all it takes is a couple solder joints, no diodes, no thermistors, etc.

How do you wire a single motor in series?

Pete

Let's try to stay on topic, the OP said this.

As I am now in the reassembly process for my Lionel 2030 with 2 DC can motors, and this engine is definitely subject to quick starts even when the "throttle" is barely cracked, I would like to know if there's a better way to control this?

 In the early 90's I used an Al Trol Memory throttle controller. It was sold by Northeast Trains. I'm not familiar with running one. But Dallee offered one as well. The Hostler. Both featured a knob to dial in momentum. The higher you set it. The slower the engine would accelerate. This had been around in HO and MRC packs for years. Both throttles were tethered and were for coventional only. They did have a memory feature and if you moved from one station to another the train kept moving. A few things did them in. Although there were workarounds. The didn't do well with Proto 1 engines. They were good with QSI boards. Lionel came out with their wireless Cab 1 as well as command engines and then MTH with DCS. That pretty much led to their demise as far as popularity. 

 The Al Trol I had worked very well for smooth starts. Worked great with the Weaver E8's of that period which I'm pretty sure didn't have flywheels. I no longer have mine. I'm sure these are still around under someone's benchwork or tucked away on a shelf.