Proto87Stores wrote:I think you'll find that on an 0-4-0 you don't need to position the transverse beams over the end wheel bearings. They still have to pivot in the same horizontal plane as the side beam pivots, and be symmetrical about them, but otherwise can be inwards or outwards of the axles.
Almost at the buffer beams will give good clearance for the transmission, but outwards will magnify any fore/aft tipping caused by the track. Inwards will of course reduce the tipping effect of the track, but give you much less room for the motor, etc.
Agreed. I await with interest how you combine drive system and the pivot.
--- If un-adjusted single spring and pin points is good for 4 wheel wagons, why do you need spread-sheets for CSB's and plain journals instead for locomotives? They are both just track guided vehicles.
Because
1. Outside frame 4 wheel wagons suit pin point bearings where as inside frame Loco's don't.
2. As you rightly went on to say, getting sufficient weight on each wagon axle is important to achieve reliable running. Most people are using 50gm/2ounces per 4 wheel wagon, which means the size of wire needed is known and comes with the kit.
3. The CSB spread sheets came about because of the need to work out where the fixed fulcrum points must go.
4. For a 4 wheeled inside bearing loco this is actually trivial as they just need to be symmetrical. The only real use for the spread sheets is to get the wire size right first time.
5. For locos with 3 or more driven axles, fulcrum placement isn't intuitive, hence the need for the spread sheet. Also there are many possible right answers which take different wire sizes to achieve the same effect.
While I am comfortable with the basic functionality of "Bill's" sprung 4 wheel wagon approach, my early 1960's teen experience makes me think that pin point bearings and and per wheel springing arrived pretty much simultaneously when I managed to afford a couple of Peco's then brand new "wonderful wagons". I don't see any particular difference in the current technology from that. Just music wire instead of nylon for springs.
That's right Peco got their first, but the plastic spring didn't age well, and, as you pointed out, they didn't use metal on metal pinpoint bearings, and they didn't weigh enough.
...I don't have much experience of conversions using custom fitted metal bearing cups and steel axle points, but the relatively high extra cost of adding the low-volume manufactured bearings should be compared with the recent low prices and advantages of imported miniature ball bearings. They easily allow a five-fold increase in weighting and inertia, while barely affecting the rolling friction. And the common fault of bearing misalignment due to a lack of hand-crafting skill, is now a thing of the past.
As a P4 modeller, who is inevitably going to replace the wheel sets, the additional cost of the metal pin point bearing is trivial, and the performance of metal on metal pinpoints is pretty dam good. Even ignoring the issue Keith picked up about the space available for ball bearings on an outside frame wagon, I'm not sure that the degree of improvement they will produce over pinpoints will be enough to make the change attractive.
... Even for traditional Flexichas loco designs, the crude high friction ideas of resting beams on the centres or ends of running axles, is transformed by using ball bearings in those situations.
I must admit I have wondered about using ball bearings were we currently have plain inside bearings. Fitting ball bearing axle blocks in our current horn block assemblies might be worth thinking about, but the 1/8" axles we use would make these significantly bigger than the current generation of plain bearings. This isn't desirable as these components can already take up rather more space in our chassis than I would like. Reducing the axle size would help, but we would need the co-operation of the wheel suppliers for that one, which might prove hard to come by.
There is also the question of whether you get significant value from reducing frictional losses on the bearings of the loco driving axles. These axles don't run free being constrained by the motor, so the startling improvements produce by low fiction bearings on othere rolling stock just aren't apparent or available. Nore is it likely that their would be an improvement in loco pulling performance. Any decently built loco chassis should be capable of spinning its wheels once the load exceeds its adhesive capability. The motors we use today do this easily, so reducing the internal fictional losses in the chassis will not produce any change in performance.