Geopat69:
A five axle trailer is a very large cap’y. over the road trailer (low boy). Usually loaded from the front, and always going to be slightly heavy on the front w.r.t. the five rear axles, in the lt. wt. configuration, that’s why it lays down on the ground, when you disconnect the goose neck for loading. After all, 60 or 70% of the real heave body structure is ahead of the rear axles. Some plans, elevations, pictures, schematics, manuf’er. name and lit. would b most helpful. There are a half dozen variations on the theme, and we can’t see them from here. Your trailer might have one or two flip axles on the rear and only three fixed axles on the trailer itself. The flip axle is hinged off the back of the trailer, hydaulicaly rotated down on to the pavement to cause about 2/5 ths. of the load to be taken by these axles. Some axles have air suspension too. Statically, the wheel loads are all equal, but depending on the reaction speed of the system and the speed of actual travel you will get some variation.
When you have one axle across the trailer, five axles sets in total, dual wheel sets on each end (one dual set on each side of the trailer, on each axle), they have to be controlled in two ways, by volume and by pressure at each axle. Two or three of the axles can also be lifted off the pavement, carried by the trailer structure during lt. travel. The hydraulic volume and its control relates mostly to pulling the axles over a hump or a valley (a curb or depression) in the line of travel, and the front, center and rear axles will have the most vert. travel, over the curve, in that process. For the most part, this sets the cylinder and reservoir volume for each axle, some iteration, engineering experience, and kinematic software involved here too. Now, if we have enough cylinder volume for the max. vert. travel we want, then we have a pressure control at each axle too, which allows the vert. dual movement, side to side, to account for the cross slope variations. Mostly, this involves no volume change, and constant pressure on both sets of duals, for equal load on each set of duals on an axle. Thirdly, the axles are all interconnected for pressure control so they share the load equally, and this will change the volume to each axle to cause this load ratioing or balancing axle to axle. That’s the general scheme of things, and the exact plumbing and wiring and pressure switches, check valves and pressure relief valves will vary from one manuf’er. to another.
There are also heavier, more specialized trailers (load platforms) which can be connected side by side and end to end to make up a bigger size (footprint) and load unit. On these, each dual set pivots and is individually hydraulically controlled for pressure, volume and steering. You can turn these on a ‘large dime’ without dragging 40 sets of wheels around the turn, and on a much tighter radius, since the trailer unit steers.