Can someone please explain to me the difference between the L-4a and L-4b Mohawks? I know that both had the 72" drivers and that they were used in dual (i.e. freight AND passanger) service for the NYC. Would one have been used in freight service over the other, or did it really matter?
According to Richard Leonard’s Steam Locomotive Archive web site, the “Class L4b was the first class on the NYC system to feature the multiple-bearing crosshead instead of the “alligator” type still used on the J3 and L3 classe.” So,
What exactly is the “multiple-bearing crosshead”?
What does it look it and what does it do?
Is this something internal or external to the locomotive?
How is it different from the “alligator” type?
Why did they call it an “alligator” type?
Sorry for the barage of questions. I posted a similar question over at both the Yahoo! NYC-Railroad and Railfan.net NYC forums but have only gotten little response so far.
The reason for asking is that BLI is planning on releasing brass and plastic versions of the L-4a and L-4b in HO later this year in the following configurations:
L-4a: #3101 & 3124
L-4b: #3149 & 3144
I’m trying to determine which version that I want to reserve but don’t know if the differences are noticable to the eye, if any.
My layout is early 40s. The L-4 Mohawks were released in '42-43 and '43-44, respectively. I’m hoping that the smoke deflectors will come either installable or detachable, since they weren’t installed on the L-4s till later on.
You got that right, my friend. I nearly fell over backwards when I found out about BLI’s future release on Friday. FINALLY!!! A 4-8-2 NYC Mohawk in plastic that’s actually more affordable!!!
On the topic of picking up more than one Mohawk. As my roster will be increasing by 3 locomotives this year:
Proto 2000 NYC 0-8-0 switcher (DCC, No-sound) - Should be arriving in the mail this week! [:)]
Special-run Stewart NYC “Cat-whisker” FT A-B (DCC, DSX sound in B unit) - Arrival: Late spring or summer (I hope)
BLI 4-8-2 L-4 Mohawk
I think for now, I’ll just stick with one. If and when prices do drop on them (less likely now that BLI plans on a limited run and reservation policy) or there’s a 2nd run, I may think about another one.
The one foreseeable issue that I may end up running into is the limitations of my curved track and turnouts. That is one lonnnnnnng tender on the L-4 Mohawk and there may be some problems with negotiating around R22" or less curves. I may end up cutting a long “swath” of trees (or structures) nearest the track. I’m almost certain the Mohawk is NOT going to like the Atlas Snap turouts.
One saving grace is that I could run the Mohawk at the club layout, as we should be nearing end of construction of Phase 2 of our construction project and getting an actual loop of track up and going by then. (Phase 1 was constructing our 40’, 15-track staging yard.) We had a good and productive work day yesterday at the club - completing three modules and two support bases - with only five or six modules to go to complete our three-track loop in and out of our yard.
Let me see what I can do. I just grabbed my copy of “Steam Power of the NYC, Volume One” (what? You don’t have a copy yet?), and looked them up. Essentially, there are ZERO differences between the a’s and b’s: they were both built in 1943 by Lima, in two different batches (A’s are 3100-3124, built in January, and b’s are 3125-3149, built in February). The NYC attached different class designations to the SAME equipment because of different order numbers (this drives us freight car guys nuts: I’ve got a dozen different diagrams for the SAME boxcar, because they kept buying batches of 500 spaced a year apart!). So the a and b designation doesn’t really matter a whole lot: both classes are essentially the same, with the a’s being marginally lighter (the b’s would have been heavuer due to wartime material restrictions)
Hmmm…not sure what he’s talking about here; I’ll have to call Richard and ask him to clarify. I’m staring at two builder’s photos (3113 and 3122) and they both clearly come with Alligator crossheads. However, on the next page is a photo of 3135 with MBCs, taken in December 1943, supposedly after they were all delivered. The rest of the photos ion the Mohawk chapter show a m
I agree with you. I would have preferred an earlier L-2 with the Elesco Feed Water Heater - a much more interesting locomotive.
I do hope BLI does a good job with reproducing the L-4. Division Point had plans to bring out a L-1 and L-2 Mohawk (maybe an L3, too?) but decided to put it on the back burner till after 2009. Who knows if and when that will even get done.
Anyhow, thanks again for the info, Ray. I always appreciate your input. [:)]
I do now. [:)] Thanks to you I just bought a used copy (in VG condition) off Amazon.com. Figured it was worth the $30 for both the pictures and reference material.
Well, I wrote BLI this morning and asked them whether or not they were planning to have the smoke deflectors as an option - i.e. the option to leave them off. I sure hope so. The release of the Mohawks ('43-'44) pretty much coincides with the era of my layout. Since the smoke deflectors weren’t added till later, the option of leaving them off would be very desirous for me.
Another question, if I may. Did the original NYC Niagaras ever run without smoke deflectors? If so, was this an option provided by BLI when they released them a few years back? Thanks.
I may be able to help with a bit of the crosshead info but as far as the L-4a and L-4b differences info is a bit sketchy…
The crosshead purpose is to reduce strain on the piston rod so the stress is reduced where the piston rod enters the packing gland of the cylinder. If the bearing surfaces get sloppy the piston rod will cause the packing to leak prematurely. Generally the upper bearing surface gets more wear as the force is greater on it in a forward direction.
The “multiple bearing crosshead” was primarily developed by the Pennsylvania RR around 1915 and has been a very common crosshead design. It has a second bearing surface which is internal to the crosshead guide. The crosshead guide is a bit taller (thicker) on this type but otherwise outward appearance is not noticable. This is an improvement over the “Dean” crosshead of about 1900.
The “alligator” type is by far the most common with a rectangular top and bottom crosshead guides with sliding shoes above and below the kingpin. Very basic and easy to repair, the top shoe and bottom shoe being interchangeable. Where the “Alligator” name comes from I don’t know. Maybe the two shoes resemble the jaws of an alligator?
When you get your “Modern Power” Vol.1 turn to page 165 and you’ll see the 6000 with the upper portion of the smoke deflectors removed due to an accident. Otherwise, I don’t ever recall seeing a Niagra with the deflectors removed. I have a pair of the BLI’s and I’ll check to see how easy, or not, it is to remove them. Looks pretty odd with them removed!
I seem to remember a photo of at least one of the Niagaras without deflectors, but I think that the photo was taken LATE in the steam era; it might have even been a scrap line photo. Lemme look through my NYC photos later tonight and see what I can come up with.
$30 is a great price for one of these books. I found my copy on Ebay for about the same price. I think you’ll find it to be a VERY useful reference work! Only one problem: once you’ve had the chance to dig through it, you’ll want a lot more NYC steam! Even the odd stuff, like small 2-6-6-2s running in central Indiana, pulling mixed freights!
I have some more questions on the Mohawk L-4s if anyone would care to answer them. According to the Broadway Ltd paper I picked up at Springfield Show last week these will have either Boxpok or Scullin drivers and Louvered or Screen pump shields. What is a boxpok driver? and what was the reason, if any, for these differences?
I was told the L-4s were used in Pacemaker service, would either driver type be appropriate?
Boxpok driving wheels have a hollow, box-section spoke, hence the name. They were a proprietary product of General Steel Castings. They look like this:
Scullinn disc drivers were another proprietary wheel type, made by the Scullin Steel Co.
In both cases the design was intended to overcome the limitations of conventional spoked wheels. Operationally there would be no difference between the two types.
Pump shields in the case of the Mohawks are I think a bit of a misnomer, since the shields appear to be primarily to protect the aftercooler pipework between the compressor and the main reservoir. The difference is merely between a louvered or screened opening to allow airflow over the aftercooler pipework.
A Boxpok is a type of steam locomotive wheel where the wheel gains strength through being a number of box sections rather than having traditional solid spokes (the name is a variation on “box-spoke”). Being hollow, they allow better counterbalancing than conventional drivers, which is important for fast locomotives. The Boxpok wheel was patented by General Steel Castings Corporation of Granite City, Illinois.
The “double-disc” driving wheel invented by the Scullin Steel Co. It was annonced in RailwaY Age magazine in late 1932. The claimed advantage was that it allowed for more counterweighing.
The differences is not that great basically they’re patentable proprietary solutions for the same problem, which is smoothing the ride of large fast steam locomotives at high speed.
Both would be appropriate. They’re roughly equal in performance.
Most large RRs like the NYC would specify the splitting of their order between manufacturers so as to spread the wealth. That would keep several companies in business, keep them in competition with each other, keep them innovating and to make sure there was no one with a monopoly on the market so as to keep the prices down.
If railroad didn’t specify the use of one then the locomotive manufacturers would split the order between parts makers f
The spokes on a conventional wheel weren’t the only weak point - so was the wheel rim. It was not uncommon for the rim to flatten between the spokes, especially if the tire was worn thin. Both Boxpok and disc drivers had far greater support for the wheel rim, preventing flattening.
Does the literature from BLI mention anything about whether the L-4s will have the smoke deflector or not? I’m hoping not but wouldn’t be surprised if they do. Thanks.
Mark & Eric,
Thanks for the additional info on the Boxpok and Scullin wheels. Good stuff! [:)]
The brochure says “Many L-4 locomotives were equiped with smoke deflectors.”
But one of my friends who was also at the Springfield show asked a Broadway rep and was told that they would all have smoke deflectors.
The brochure ends with “Building the most accurate and best running Mohawk is the goal of this project for our deserving customer.” Model train companies seem to be responsive to input from knowledgable customers lately, so I would encourage anyone who wants to ensure the accuracy of this model to contact Broadway Ltd directly with any relevant info.
