Those of you that understand loco valve gear will have to excuse this basic query - I am reassembling an HO articulated with front & rear 4 axle engines.
If the Loco is viewed side on then should the valve gear on the front & rear engines on the same side of the loco be synchronized?
By synchronized I mean should they be set up to mimic each other’s valve gear action??
(I am aware the ‘other side’ of the loco should not be synchronized with the side being viewed )
Thank you
Tanked
The engines on a articulated steam locomotive do not need to be synchronized. On the prototype, the engines would go in and out of sync.
Thank you
Tanked
If I understand what you are asking, I think the short answer is, no. However, they do mimic each other’s action, but not necessarily at the same time. The front could be exhausting while the rear is applying reverse power or any other combination one could think of. Because the drivers slip they are very seldom performing the exact actions at the same time.
Articulated locos where prone to slipping like many other locos depending on adhesion of the rails. The below from a Google search.
The PRR insisted on using poppet valves (instead of Walschaerts valve gear) on the T-1s. Maintenance on poppet valves turned out to be high. According to most books on the subject, the T-1s turned out to be slippery locomotives even at speed. Why wasn’t this known after testing the 6110 and 6111? The 6110 and 6111 were tested under ideal adhesive conditions. The later batch of T-1s ran on a larger portion of the PRR system and under all conditions. Even though the factor of adhesion was designed to be greater than 4.0, the slipping problem was never solved. At least that is what “the books” claim…
It should be noted that the retired enginemen who actually ran the T1s claim that they were not unduly slippery (even at speed), as most authors have claimed. Their secret to starting trains was to put down a little sand when stopping, a little when starting, and to use a light throttle up to 25 mph. Their secret to avoiding high-speed slipping was a longer cutoff coupled with partial throttle. The T-1s ran very well at speeds over 100 MPH.
If the story ended here then the Q-2s would not have all been on the “dead line” in 1952 while the J-1 class was still going strong with some even running in 1959. Working out on the “treadmill” for the Q-2 was not the same as working out on the “road.” In service between Pittsburgh and Chicago, the engines slipped badly at running speeds. It was not hard to make a reciprocating steam locomotive slip its drivers in starting, particularly if the rails were wet or slick and if the person at the throttle “gunned” it carelessly or deliberately. But the Q-2 just could not convert all that horsepower produced at the c
Tanked:
I think I know which articulated you’re re-assembling, and for ‘show’ you might want to put them about a quarter turn out of sync, which will mimic the difference between high and low pressure cylinders. I do this as a matter of course on my articulateds, both simple and compound, because as the other posters have said, the drivers went in and out of sync as the prototypes operated. With fixed gearing on models, we don’t have this option, so a quarter-turn will give the impression that the locomotive is really ‘working’, and besides, it looks 'cool ’ when it’s running [:P]
Tom [:)]
Both my PCM Y6b and my Rivarossi H-8 came with the drivers all synched. I removed the cover plate on one engine, pulled up the driven axle, and purposefully shifted the whole driver set about 30 deg from the other one. I like 'em slipping a bit. [:D]
-Crandell
Rich, your post is all correct, but the OP was questioning articulated loco synchronization, and the Pennsy T1, Q1, Q2, et al., were not articulated. They were duplex, having a one-piece single frame for the two steam engines.
Tanked, as others have posted, since the two engines are completely independent, they are not synchronized in any way, other than having a single throttle. In fact, they ride smoother and are easier on the rails when they are out of synch.
Due to slippage it would be almost impossible to maintain sychronization for very long.
Tom
Yes, its that one - thanks for your help.
Learned a lot along the way.
For example, Rivarossi make articulated ‘right angle’ gearboxes that have 11 teeth on the vertical shaft gear in the Gbox, & also a 13 tooth version!.
I know because at 1 stage I had one of each installed & was fascinated to see one set of wheels going like hell & the other sedately turning over.
Things returned to normal when I put a pair of 13 teeth Gboxs in.
Ended up using 1/16" ID neoprene tube as the drive from the motor to the 1st Gbox .
If you don’t wish to have your elderly & slightly canabalized 2-8-8-2 back then having learned a lot about them from pulling the one I fixed up apart so many times I think I will restore yours.I have enough pieces gathered up along the way.
The most pleasing aspects of the resuscitation of cab 2197 have been the asistance from forum members, reward for persistence [aka stubborness], and the satisfaction that 2197 is by far the quietest & smoothest running of the three 2-8-8-2’s in the stable. So, after I have rebuilt a Cab Fwd, the other 2 will probably get a going over.
Cheers
Tanked
Nomenclature freak reporting, suh!
Judging by the preceding posts, the OP’s original question referred to the side rods and main rods, not the valve gear!
The valve gear (Baker or Walschaerts) settings on both front and rear engines are supposed to be identical. On any US prototype loco, they are all connected to the same power reverse cylinder.
Model Baker valve gear sets are usually fixed-unit castings, so no problem. Walschaerts valve gear should have the radius rod (from the link to the combining lever) at the same angle on both sides of both engines.
Note that this has nothing to do with keeping the drivers of the two engines in sync, and everything to do with keeping steam consumption balanced.
Chuck (Modeling Central Japan in September, 1964)