I was planning on asking the

I was planning on asking the same question on the decoder,  It's an awesome model but I will not waste my money on TSC decoder with there dc train like control, I'm ordering one with DC and install my own Loksound decoder.

M420

From what Ive been told the P&W units are 6 inches longer. Keep in mind that MLH was told that a P&W version will be forthcomming. For what its worth.

Different carbody

The top of the carbody is different as well.

Scott Chatfield

M420

The Rapido annoucement says the P&W units required a different bolster design and truck spacing.

You can find information on

You can find information on the M-420 at thedieselshop.com: http://www.thedieselshop.us/DataM420.HTML

According to this site for M-420, M-420R, and M-420B the truck wheel base is 9'-4'' for all three types. Length between pilots (52'-4'') as well as distance from pilot to truck centers front and aft (7'-8'') are identical.for M-420, M-420R. That leads to a truck center spacing of 37' for both.

I don't know how reliable this information as the give distance between truck centers as 47'-05" / 45'-09"?????

There were two versions of the AAR type B truck. Trucks with GE traction motors had a 9'-4'' wheel base, trucks with Westinghouse traction motors 9'-10''. http://ibls.org/mediawiki/index.php?title=Diesel_Trucks#Drawings_3
/> Regards, Volker

Edit: The Trainiax website contains 1:36 drawings of 4 different MLW M-420R locomotives: http://trainiax.net/mescaleloco-results.php?build=MLW&dtype=UT&type=M-420R&rebuilt=N&lrtype=L&scale18=1&scale36=1&scale55=1

and 49 drawings in different scales (1:18,1:36, 1:55) of the MLW M-420: http://trainiax.net/mescaleloco-results.php?build=MLW&dtype=UT&type=M-420&rebuilt=N&lrtype=L&scale18=1&scale36=1&scale55=1

From Rapido

Here is some info from Rapido. I asked similar questions a week or so ago.

Mike Confalone

Hello Mike,

Thank you for your email.

I understand your concern regarding the use of TCS decoders. No, we are not completely switching to TCS for all our products and we have several engines which are in the works being designed for ESU decoders. The reason for using TCS was to have an alternate provider in case the tariffs imposed on Chinese and European products would be imposed on us which would affect both our margins as well as the MSRP.

From a design standpoint, the M420 will be fully compatible with an ESU 21 pin V5 decoder. Moreover, ESU has agreed to develop a sound file available for download for the Rapido M420s. This is the option we are providing so that modelers such as you can purchase the DC version and easily upgrade it to a DCC. It will not affect our warranty on the locomotive.

Yes, the motor issues have been resolved by making some programming changes as well as switching to a different motor manufacturer. The new motors have already proven to be very reliable with a failure rate of less than 0.1%. For the FA2s, FB2s and the M420, we have already switched to these motors. I can say with certainty that the M420s will have no operational issues.

I hope this helps.

Best regards

Mohan George

Depending on the price

Comparison between M420

The Great Western Railway in Southwest Saskatchewan (Canada for those not familiar) ran a fleet of M420 from both CN and P&W.  I took some detail shots that can be used for comparison:

 Ex P&W unit

 ex P&W M420 - small fuel tank

 ex P&W unit rear truck

 Ex CN M420 via Lake States RR front truck

 GWR Ex CN M420 - This is a first order M420 with large fuel tank, Rapido will be doing the medium size second order M420, P&W has the small fuel tank option similar to the BC Rail units. 

For whatever reason I don't have a broadside of the ex P&W unit but you can estimate the truck centers from the carbody on the two units.  Hope this helps.

Marc Simpson

M420 General Arrangement drawing dimensions

I have a photocopy of the Bombardier specifications document for the M420.   The dimensions given on the General Arrangement diagram are indicated two ways.  First is X' Y" and second as total inches in parentheses.   

The ZWT truck wheelbase dimension is 4' 8" (56") from each axle centerline to the truck centerline or in other words, 9' 4".

The dimension between the two truck centerlines is 36' 5" (437").

The front truck centerline to front pilot dimension is 10' 5" (125").

The rear truck centerline to rear pilot dimension is 9' 10" (118").

Pilot to pilot dimension is 56' 8" (680").

The first two P&W M420Rs, based upon information in the X2200 South Nov/Dec 1973 issue, don't appear to have used trade-in trucks, so the AAR-B trucks were new and would be equipped with GE752 traction motors.  The wheelbase therefore should be 9' 4".   I couldn't find any detailed information for the 3 units in the second delivery, but presumably they too were riding on new AAR-B trucks with GE traction motors.

Hope this helps.

John

RE: Depending on the price

Hello Joe,

Rapido has generally followed a practice of having the DC equipped units having exactly the same lighting circuits as the DCC version. One just has to pull the dummy plug and replace it with either a straight DCC or DCC/Sound decoder that has the functionality to control said lights. Usually that is a LokSound with 21 pin plug, others may work but I haven't investigated them.

The icing on the cake is that the speaker is also installed at the factory on the DC versions too (except for some of their earlier releases).

Regards,

Mike MacLatchy

PW trucks

The delivery photos of PW 2001, 2002 clearly show AAR trade in trucks. Rapido has said that the PW units will require different tooling on some of the roof areas as well as some other minor differences.  The BC Rail units will also require some of these changes. Rapido has started that these units will be among the second run. P&W had five units in four paint schemes, the 2003 was never repainted and left the railroad in its original colors. 

Thank you

Apologies for taking so long to respond.  Besides yesterday being Valentine's Day, it was also my wife's birthday, so my focus was on her.

Thank you all for the great info.  Given what you've shared, it sounds like, aside from the sideframes, the only difference in the trucks and truck spacing is that the M420 trucks are 1" and 7" closer to the front and rear pilots, respectively, than they are on the M420R.  To me, that difference is so small as to be meaningless.  Very good news for me.

rtld614 and mecu18b, I believe you mentioned that Rapido will be doing the M420Rs as a certainty.  Is that a recent change?  Right after the M420s were announced, Rapido replied to my email asking about the M420Rs and said that they were considering them, but whether they actually happened would depend on the demand.  Have they since announced them as a sure thing?  If so, I'll happily wait, but if not, I'm on the fence about whether to grab undecs from the first release.

Scott Chatfield, do you recall the specific differences there?

Bump

Scott Chatfield, rtld614, and mecu18b, I'd be really grateful for any further insight you could offer on my questions above.  Thank you all in advance.

If you insist....

The differences are in the engine air intakes just ahead of the radiator and the roof extends over the radiator on the P&W/IAIS units.  They also have vertical rear headlights and I think the stepwells were different as-built.

Of course the big difference is the P&W units builder plates said "M420R" while the CN's were "M420W".  Given Joe's, um, attention to detail, I expect he'll make sure that's right on his models....

I thought the P&W's were called M420R because they used some traded-in parts from RS3s, including the trucks.  

Scott Chatfield

Scott

Hahaha!  I'm not sure whether that was intended as a compliment, but, uh...thanks!

That was always my understanding as well, but only based on discussions like this.  I don't recall ever seeing anything official on that subject.

M420R response from Rapido

I hadn't heard back from anyone here on the above question, so I messaged Rapido again for an update on whether the M420R was a definite "go".  Here's their response: