P2 Locomotive Company and related matters

Maybe but I had the same issue with downloading a motor insurance certificate today which definitely was https and I could see that the file had downloaded.

 

That's odd, then? As mentioned, FF says "hang on a minute" but then offers you the option to download it anyway. Has your browser had any recent updates that stop you viewing PDF files directly in your browser, do you know?

 

Good stuff.

What I can’t see is a plan view of the cams showing the taper?

The issue with the original Lentz gear iirc was that the cam follower was square (not sure if it was a roller or just a push rod) so you had full contact on the heel of the cam, but as the shaft rotated and the taper came to bear, you ended up with just an edge contact. As drivers like to chose a set number of cutoff positions eg 55, 45, 30, 15 etc then the cam follower would wear a grove in the cam at those points, and hence why the stepped cam was introduced.

Now, did the Franklin gear introduce a roller follower which was also pivoted to allow it remain in full contact as the shaft rotated?

 

There is a difference. For the Franklin files, Google doesn't download, presumably just because it is http and not https. I just used the address in Edge. For my insurance certificate, it does download, there is print but it's so dark that it cannot be read. I just opened the file with Foxit.

 

No, I couldn't see any obvious taper. I'll have another look tomorrow - too late tonight!

 

For completeness, here are the patent details for Franklin A:

Drive system: US2183327A.pdf

Reverse Gear: US2385957A.pdf

Just out of interest, here is the patent for ACE3000. It had what the PR T1 should have had - inside connecting rods linking the two (in this case HP and LP) power units!

US4425763.pdf

 

Taper is probably the wrong description. Franklin B is probably analogous to automotive VTEC as here:

https://en.wikipedia.org/wiki/Helical_camshaft

Refer to Fig 1.

Taper is probably used to describe the function rather than the mechanism.

 

The cam is part no 55a in sheet 4 of US2441199A.

 

This came up on another thread, a further development https://patentimages.storage.googleapis.com/.../US2518403... poppet valve / long compression system, wonder if the P2 team are aware of this though a P2 is probably not going to face the same potential slipping factor that the American locos with 4 or even 6 wheel trailing trucks had.

 

Can you make that bigger?

 

From Sean’s link above, this pic illustrates very clearly the cam profile as I understand it, albeit very elongated in this case …

 

I bet you say that to all the Boys/girls/them....

Best i can do is refer you to the Advanced steam tech thread on farcebook https://www.facebook.com/groups/399471963535816/
the post considers the merits of...

 

The problem with all these Franklin designs is that they appeared at the end of steam in the USA and therefore their use was very limited. Unfortunately the one class that made major use of Kirchoff's designs, the PRR T1s, being high powered duplexes, were very prone to slipping, even at speed. This resulted in broken valves. The different versions were designed (and warranted) for use up to 100mph with short bursts up to 125mph. That the design was seen as a failure was due to the locomotive design, not the valve gear. This could have been cured with inside connecting rods but this was against American practice. Most of the T1s had the oscillating version, one had normal piston valves and only one with rotary.

Incidentally the high speeds allegedly recorded with the T1s may be related to the notoriously inaccurate placing of US mileposts!

 

With with this kind of gear the P2 has the potential to be a good high speed cruiser as well as having superlative ' grunt' , i sincerely hope it works out as well as Tornado did straight from the box.
Mile posts aside ...think its fair to say that Mallards supreme effort down stoke bank could have be readily replicated by the likes of a T1, its Deutsche-bahn rival or even a Duchess in a Bathtub...

 

Except that poppet valve gear's main advantage is at high speed which the P2 was not intended for. In France, where passenger trains at the time were limited to 120kph, Chapelon;s 242A1 had conventional piston valves.

I'm not sure whether USA milepost errors are/were cumulative or just point-to-point but the T1s were timed over some distance not just a 1/4 mile.

 

For 2007 i think a lot of getting to 70 and staying there as long as possible will be the order of the day.
The original P2's I grant you, and the Lentz gear seemed an odd choice for that, but then 6ft 2 driving wheels seemed an odd choice too... imagine the 'pick up' with 5ft 8's and walshaerts, shorter wheel base allows a shorter boiler both plusses...

 

Franklin's penultimate valve gear project also ended in failure, although, again it wasn't due to the company. C&O had had good results with Type A poppet valves installed on Class L-1 4-6-4s. They wanted to use Type B (rotary) on five new Class L-2-As, which were among the last steam locomotives built in the USA and the last express passenger locomotives. Big and heavy, the L-2s were intended for high power at 50 to 80 mph with passenger trains on C&Os difficult topography. They were built by Baldwin. The preceding eight Class L-2s locomotives had Baker valve gear.

As soon as the first L-2-As went into service, problems occurred with the valve gear. A transverse shaft involved in adjusting the position of both cams for different cut-offs snapped on two different locomotives. What Ray Delano, the Franklin Engineer, found was a total puzzle. He could find no apparent reason for the shaft breakages. Each cam was driven by its own gear; the two cams were set 90 deg. apart (the cylinders on a 2-cylinder locomotive also being 90 deg. apart). If the cams and driving wheels on each side of the locomotive were 90 deg. from those on the other side, there should be virtually no stress on the cutoff adjusting shaft, which was the only connection between the valve gear on either side. The observation suggested a thought to Delano, but one which he at first discounted. Could the drivers on the affected engines be improperly set on their axles - "out of quarter" (not at the prescribed 90 deg.)? Given the way a driving wheel pair is mounted on a new axle at the shop and and the crankpins machined using a "quartering machine", such a thing should have been impossible. By careful measurement however, it turned out to be true. Inexplicably, each pair of drivers on the two locomotives was out of quarter, by the same few degrees. It was enough to do the damage.

The L-2s and L-2-As were quickly scrapped by 1953.

https://en.wikipedia.org/wiki/Chesapeake_and_Ohio_classes_L-2_and_L-2-A