billbedford wrote:Proto87Stores wrote:However, what doesn't seem to be mentioned much on the forum is that merely fitting springs to wheel bearings does not itself provide a springing motion unless the spring rate is low compared to the weight of the vehicle supported by that wheel.. For those using horizontal wires, what seems to be the only consideration, even for CSB's, is balancing the wire thickness to achieve the required 50% static displacement position. But the thickness of the wire and its length between fixed supports affects its spring rate. You can therefore accidentally, or deliberately end up with different spring rates while still achieving the 50% balance position.
Sorry. 50% of what exactly?
grovenor-2685 wrote:Somewhere among Bertiedog's postings in the RMweb archive there was a better description of the Varney system complete with an illustration from a Varney catalogue. If applied as intended it should not hold everything on the bottom bump stop, the adjustment allows the spring force to be set so it rides at the mid point like a CSB.
From Scalefour Suspension digest
5 Requirements for model locos
The main requirement for good running consists in maintaining continuous and consistent contact between all wheels and the track:
Continuous contact is achieved by allowing wheelsets to have vertical movement with respect to each other; this vertical movement is achieved by hornblocks or axleboxes (or tubular bearings) that can move up and down in the loco frames or chassis (see figure 1).
This is the absolutely basic stuff of working suspension.
As per Keith's above, and others earlier posts on this topic, CSB's and and other spring systems, even such as your wagon springs, typically want and assume that the static on perfectly flat track spring position for each wheel is at least approximately at the 50% point of it's up-down movement - So that there can be Up-down movement.
I thought we'd moved on enough so that I could show that lightweight vehicles, such as you just previous suggestions for empty open wagons, need very much softer spring rates than normally weighted vehicles.