Need some P42 dimension data

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Need some P42 dimension data

Postby Steve F45 » Wed Jul 01, 2015 11:01 pm

I am looking for some P42 dimension data that I am having a hard time finding. What i need is the overall length, distance between truck centers, locomotive wheelbase? These are to be used for converting to ho scale for a custom project.
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Re: Need some P42 dimension data

Postby NorthWest » Wed Jul 01, 2015 11:48 pm

Steve F45 wrote:I am looking for some P42 dimension data that I am having a hard time finding. What i need is the overall length,

Assuming Wikipedia is correct, (and I think it is, based on comparisons with other vehicles)
69'

distance between truck centers,

43' 2.5''
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Re: Need some P42 dimension data

Postby DutchRailnut » Thu Jul 02, 2015 12:17 pm

length 69 ft over coupler surface
height 14 feet 6 in.
width 10 feet
bolster centers 43 feet 8 in
wheel base 9 feet
wheels 40 in
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Re: Need some P42 dimension data

Postby Steve F45 » Thu Jul 02, 2015 10:02 pm

Thanks guys. Could any of you provide the same info for the ES44AC?
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Re: Need some P42 dimension data

Postby NorthWest » Thu Jul 02, 2015 11:51 pm

ES44AC:
Length: 73' 2''
Width: 10' 3''
Height: 15' 5''
Distance between truck centers: 53''
Wheelbase: 13' 2''
Wheel diameter: 42''
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Re: Need some P42 dimension data

Postby Allen Hazen » Sat Jul 04, 2015 2:06 am

Published heights of diesel locomotives are a pain: ar they measuring over the roof, over the top of a somewhat projecting exhaust stack, or over the top of the bell of the roof-mounted horn?
--
Model Railroader has published scale drawings of both the Genesis (original, P40, version, but I don't think the dimensions have changed) and the ES44, both I think at a scale larger than HO.(*) I will try to look for them and post references tomorrow. Until then… Louis A. Marre and Paul K.Withers, "The Contemporary Diesel Spotter's Guide" (published by "DieselEra," 2008) gives overall length and truck centre distance. It agrees with Dutch on the P42 and with NorthWest on the overall length of 73'2" for the ES44, but says the truck centre distance for the E44 is 50'4".

Truck center spacing for six-axle units is a bit problematic, since the centre of rotation of the truck and the centre of the middle axle are usually in different places.

(*) Added nuisance of having to convert to HO, but on the other hand the larger drawings are easier to measure to get prototype dimensions.
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Re: Need some P42 dimension data

Postby DutchRailnut » Sat Jul 04, 2015 12:05 pm

P32acdm - P40 - and P42 all have same dimensions.
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Re: Need some P42 dimension data

Postby Allen Hazen » Sat Jul 04, 2015 2:24 pm

Found drawings. "Model Railroader" for November 2004 has (S-scale: 1/64) drawings of an ES44AC, and for January 1994 drawings (same scale) of a P-40. A few dimensions marked; others could be measured from the drawings.

The ES44AC is painted as BNSF 5724, and has the (non-radial) "roller blades" trucks. Length over the end plates is marked as 69'4": the couple pulling faces seem to be 23" outboard of this at each end, for an over-all length of 73'2". Truckcenter distance is marked from the centre axles of the trucks: I don't know if the rotational centres of the trucks are at the same location. Truck centre distance is given as 46'3", with 11'6.5" beyond this at each end to the end plates. (Truck wheelbase shown as 13'2", with equal spacing between the axles.) Width is shown as 9'11", over what seems to be the cab side walls: you'd have to lose the rear view mirrors (?) and the sun shades over the cab windows if you really want to fit through this narrow a space. Height is shown as 15' 5.25" over the cab roof: top of stack is maybe 4 or 5 inches over this, top of bell of the centre horn maybe another 5". … Deck height (from walkway) is 5' 11.5" above the railhead. (Drawing initialed JWC: caption says drawings (of this and some non-GE locomotive on the following page) are "drawn for MODEL RAILROADER Magazine by Jeffrey W. Capps and Jay Smith. I think they are carefully done, though I have spotted small errors in some "Model Railroader" drawings in the past.)

The P40 (Amtrak 814) is shown as 69' long over … something: the front of the measured line seems to be at the lower edge of the pilot snowplow (with the coupler pulling face maybe another two inches out from this), the rear through maybe about where the knuckle of the coupler of following car would fit. Eyeballing it, it looks as if the length over pulling faces might be 2 or 3 inches greater than the length shown, and the length over carbody sheet metal (front of nose, rear wall) maybe as much as 8 inches less. 13'5" from the front of the 69' marked line to the centre of the front truck, 43' 2.5" between truck centres, 12' 4.5" from centre of rear truck to the marked rear end. Trucks are of 9' wheelbase. Width 10 feet over, it appears, the carbody side sheets. Height 14'6.5" over the top of the stack, which really is the highest point: horns are recessed, so don't project above this. The actual roof of the carbody is maybe 3.5" or 4" lower. ("Drawn for MODEL RAILROADER Mgazine by Steven G. Davis")

I don't know if these issues are still back-orderable from the publisher. If you think the drawings would really help you -- there are a lot of other things that could be measured on them -- I could provide photocopies.

(PS: Dutch-- I suspected the various Genesis types had the same carbody dimensions, but thank you for confirming this.)
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Re: Need some P42 dimension data

Postby Allen Hazen » Sat Jul 04, 2015 2:38 pm

Hmmm… Comparing with figures given earlier.
… I suppose the 69' length shown by "Model Railroader" COULD be over the pulling surfaces of the couplers: I was eyeballing a drawing, and judging how thick the knuckle is at 1/64 scale isn't something I'd want to bet my life on. The 43' 2.5" between trucks is measured from the midpoints between the two axles on each truck: Dutch says 43' 8" between "bolster centres", and the rotational centres of the trucks (which I have seen described as "bolsterless") might not be exactly half way between the two axles. (Truck design is a specialized and complex technology, and not one I can claim any master of!)

Difference between the width figures for the ES44AC might be walls to handrails. As for the truck spacing...
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Re: Need some P42 dimension data

Postby DutchRailnut » Sat Jul 04, 2015 2:56 pm

The figures I gave earlier are dimensions in GE manual, I bet they beat model railroader any time.
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Re: Need some P42 dimension data

Postby Allen Hazen » Sun Jul 05, 2015 1:38 am

Dutch--
A choice between "Model Railroader" and an actual GE document? No choice at all! I totally agree with you.
The "Model Railroader" drawings were what I had at hand, so I quoted them… with what I hope were appropriate disclaimers!
Thank you for reporting that your figures were from a GE manual: identifying sources is one of the first principles of scholarship, and valuable even in amateur railroad scholarship.
--
The main discrepancy between your (GE-derived) and my (MR-derived) dimensions for the P-40 is 5.5" in the "truck centre" length, and (until someone who knows better corrects me!) I think this is probably not a matter of error on one (almost certainly my) side but of measuring different things. "Bolster" is used, isn't it, for two different things: a cross-member in the structure of the truck itself and ("body bolster," I think) the structure on the locomotive frame to which the truck is connected. So no contradiction, I think, between your GE document's giving a distance between "bolsters" and what I think I have read elsewhere, that the (Krupp-designed, I think) trucks on the P-40 are "bolsterless": the truck itself does not have a bolster, and GE gives the distance between body bolsters on the underframe.

(Does this seem plausible to you? As you know, I am an amateur, and quite capable of misinterpreting things I have read!)

My guess is that your distance is that between the rotational centres of the trucks: the centre pins on conventional trucks that have them, or the "virtual" pivot point if the Krupp truck has some more complicated kind of linkage to the locomotive frame. And even though the truck LOOKS symmetrical, I wouldn't be surprised to learn -- as I have if my conjectures are right! -- that the rotational centre of the truck is 2.75" away from the centre of the gap between the axles.

Apologies for being so longwinded: I'm trying to be clear, and not confident that I know the correct technical terminology.

And I'm grateful that you, a working railroader with access to "official" documentation, are willing to take the time to educate us railfans!
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Re: Need some P42 dimension data

Postby DutchRailnut » Sun Jul 05, 2015 6:37 am

whatever turning point of truck is, cause yes the Krupp trucks are bolsterless , so it may not be the center of the truck !!
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Re: Need some P42 dimension data

Postby trainiac » Wed Jul 29, 2015 9:18 am

I found a low-res P42 diagram online that shows a distance between the truck centers of 43' 2 1/2". When I compared that to a series of P42DC direct side-view photos I'd taken (and assuming "center" is the midpoint between the axles), that dimension matched. Perhaps I'm wrong, but I can't see how the truck center could be anything other than the midpoint between the axles on a symmetrical 2-axle truck - and using a distance of 43' 8" between the truck centers doesn't seem to match the rest of the P42 proportions. I don't know if this applies to the P40-P42, but GE has a history of occasionally changing dimensions (such as using three different combinations of frame length and truck centers on 4-axle Dash-7's) and their own drawings don't always match what later gets built.
http://www.the-blueprints.com/blueprints-depot/trains/trains-n-q/p40-42bw.gif

I've used CN and NS diagrams as reference for making some of my drawings. The dimensions are the same between the CN and NS ES44DC/ES40DC diagrams (and all dimensions also apply to the ES44AC). The CN ES44DC diagram is here (incorrectly listed as a Dash-9):
http://www.cnrphotos.com/gallery2/main.php?g2_itemId=18563&g2_imageViewsIndex=1

For the ES44DC, I used the RR diagrams in combination with detail photos to make my own versions here - the drawings are 4 pixels per scale inch, so any dimension can be gathered from the image:
http://trainiax.net/mescaleloco-results.php?build=GE&drawing=undectype&type=ES44DC&rebuilt=N&lrtype=L&scale18=1

Regarding the discrepancy in truck centers (46' 3" vs. 53') - the "truck center" probably doesn't line up with the center axle, but I can definitely say that the distance between the center axles on the Dash-9 and ES series is 46' 3". A distance of 53' combined with a truck wheelbase of 13' 2" would push the ends of the trucks beyond the end plates.

Regarding the ES-series height, a deck height of 5' 10 3/4" (per the CN and NS diagrams, plus photo measurements) makes the height over the cab roof 15' 5 1/8" - the height of the cab over the walkway is 9' 6 3/8". The edges of the exhaust stack are about 3" higher than the cab roof, and the horn is about 2 1/2" higher still - but the highest point from what I've measured is the antenna dome on the cab roof, which works out to around 16' 0".
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