Thread: Tandem Suspension Concept

Originally Posted by rick130

It's nice to see the Australian wine industry is being well supported in this thread, although I limited myself to one glass last night

So did I Rick

Originally Posted by Slunnie

Its just a boat trailer.

Do aussie boat trailers not have brakes?

What I'm getting at, is that some suspension designs will hop when brakes are applied which leads to some pretty strange handling. Stuff that might not be noticed on a sealed road, but offroad with more suspension travel could be a major hassle.

Originally Posted by Dougal

Do aussie boat trailers not have brakes?

What I'm getting at, is that some suspension designs will hop when brakes are applied which leads to some pretty strange handling. Stuff that might not be noticed on a sealed road, but offroad with more suspension travel could be a major hassle.

Brakes are needed >750kg (GTM). This one will need brakes.

Steve, it doesnt have to be a hardcore situation to put you in a pickle. My work trailer (1.8t) is dual axle....and on more than 1 ocassion I have had the experience...usually only a slight decline with slippery surface ie wet grass or very loose powder dirt or mud...

Here a few scans of heavy truck tandem suspensions. Note that truck leaf springs and the Chalmers beam do not have bush, pin, and eye on the spring ends but run in slipper pads on the axles. Drive and brake torgue and lateral location is handled by the rods, etc. Unfortunately, I do not have a schematic of the Mitchell suspension.

Here are some more. These scanned better because they are not so old and faded.

Brian,
Thanks for scanning the images in. Those designs would be challenging to incorporate within the boat trailer envelope.
Camelback inverted leaf spring is looking positively simple in comparison!

Ben, thanks for your input too. I might take some of your assumptions to task BUT am happy to let the red factor account for them
I recall now that the first draft of the setup (one I emailed to you) included an idler link that converted the downward movement of the first axle link into horizontal motion only to allow linear loadings only on the strut. I left this out to minimise components, thinking that the strut would be mostly acting against the arc of the first link and thus relatively efficient...

Dougal, I will run override hydraulics on the front axle to keep this thing legal. Maybe on both axles, see how the mood strikes me. Offroad if they pose a problem they will be easy enough to lockout.

Serg, Your experience is important. I havnt ever dragged a tandem into the places where we regularly take singles. I guess though - is it a deal breaker? Would you trade the load capacity/shared resources of a tandem just for better downhill tracking?

Steve

most of the truck suspensions listed earlier are good IF you can incorporate them in a smaller vehicle but i think for simplicity,ride, load sharing and brake performance a linked air bag set up would be best and is proven on the heavy vehicles
most of the fleet where i worked had the walking beam set-up "Hendrickson" and the few Japanese vehicles had the inverted main spring similar to the camel back, bear in mind the camel back in macks was a pretty rigid (read jarring) suspension