ing. wrote: ↑10 Mar 2025, 18:37
Farnborough wrote: ↑03 Mar 2025, 09:01
From that schematic, it would look like there'd be need of a "bell crank" arrangement at the steering rack end where is exits the chassis. Without which it could move the control arm just outwards rather than linear "push" to move the wheel assembly. In effect, it's of this arrangement at the wheel end by the geometry offered in that drawing, this by the detail it looks to have..
If the steering arm passed outside the wheel upright centre (effectively rewards of that on chassis layout) it would in effect use the upright as the outer bellcrank, that's according to the schematic presented.
Perhaps this is what the area is that Zac was alluding to in more radical approach.
I also believe there may be some mechanism to convert the linear movement of the steering rack end points to something more aligned with the angled steering tie rod instead of a conventional arrangement which would create some rather high side loads on the steering rack assembly. The latter is maybe what Wache was alluding to with regard to his comment about “high loads”.
As regards a bell crank arrangement, this would not work (without an additional linkage) due to the arc described by the crank vs. the linear motion of the rack. Any more additional linkages in the system would only result in potential play in what should be a very system.
One mechanism possible could be a sector gear arrangement and each end. So, like the steering input pinion mating with gear teeth on the rack, here the rack ends would be geared to mate with sector gears mounted on a vertical axis, with a lever arrangement opposite the gears.
Yes I can see that scenario too. In elaboration of my (bell crank) comment, I'd visualised more having a rack with centre point takeoff (much as used in many road car arrangement, well principle of at least) with "dogbone" short links out to bell crank mounted at either end of the whole assembly. In effect a "blind" ended rack with centre point output.
Certainly could produce raised load in those components, but obviously they've approached it with something in that way of solution.
Currently I'm working on a failed bell crank component from within a rising rate rear suspension link in restoring a French downhill cycle race frame. Originally of aluminium alloy and likely a forging, containing three bronze bushes to operate, but with clear and obvious creeping into ovality around each bush, very close to failure. So far modelled in software, 3D printed output to check increased radii to help with load mitigation, proposal to machine in steel for ultimate long-term lifing as everything says its marginal in original which is no longer available. Probably same area of load range and component sizing to this steering topic.