Thread: LR air strut suspension

Chris
Why would you need a double wishbone geometry
If the strut can take the applied loads in double wishbone geometry it will be more than capable of the loads in a single arc of a radius arm

Depending on Offset range of bag might need to trick the upper mount a little but I doubt it

My only fear is the rear struts will be too heavily sprung for a 1500-2000kg trailer

Steve

Hi,
Just caught up with this thread. I'll try to measure tomorrow. Might be interesting to see if. TDV8 RRS are the same or not!

Originally Posted by roverrescue

Chris
Why would you need a double wishbone geometry
If the strut can take the applied loads in double wishbone geometry it will be more than capable of the loads in a single arc of a radius arm

Depending on Offset range of bag might need to trick the upper mount a little but I doubt it

My only fear is the rear struts will be too heavily sprung for a 1500-2000kg trailer

Steve

I only asked as the D4 strut has a single pin at the bottom end, unlike the strut posted by p38rover that has two mounting points at its bottom end, which allows a rigid mount to a lower arm.

Could the "heaviness" of the ride be adjusted by varying the position of the strut fulcrum between the arm control pivot and the wheel?

Chris

Chris - understand now
Yeah agreed I would use d3/4 strut with the single eye mount lower to simplify geometry.
Ideally it would be awesome to find a pressure /load / height / spring rate graph for the d3/4 strut similar to what Is published for firestone bags.
With that everything would be clear.
As you say changing the geometry could be used to alter effective spring rate

My assumption is the relatively small air volume of the struts in question - with no rolling sleeve will mean they have a relatively narrow range of pressure / height / spring rate with a sharp rise in pressure (spring rate) as stroke increases... as opposed to a rolling sleeve spring which has a long linear portion of rate vs stroke.

Will do some looking around for info on them

S

Both front and rear air-springs have a rolling fold. The rear springs are much larger diameter than the front.

A few photos.
Well hopefully I have loaded them ok.

Originally Posted by rangieman

I think your onto something here and i like your theory for a boat trailer with the ability to raise and lower the suspension for launching and retreaving aswell as ride and durability
I like thinking out side the square it is all part of being a Real Landy owner
Dont let the nay sayer`s put you off

I agree, if nobody thought outside the square we wouldn't have any technical advancement......go for it.

Cheers, Murray

I figure I may as well add stuff to this thread to keep my rambles in one place

2015 model Discovery -
max front axle mass 1450kg, rear axle 1855kg
My calculated tare masses
Tare front axle 1125kg, rear axle 1450kg

I then measured lower control arm pictures on the net with estimated distance from mount to strut to total arm length 70% front 75% rear
Then using beam calculator for applied force on cantilevered point
the following individual strut loads (converted to kg to keep simple)

Front at tare 810kg at GVM 1035kg
Rear at tare 960kg at GVM 1240kg

Now this is roughie roughie but essentially using a strut with no mechanical advantage as I propose on a 1500kg ish trailer the fronts are likely Suitable with
Trailer axle loads similar to tare loads of strut....

the rears likely a little to high a load rating
BUT considering the rear struts have much longer travel I'm thinking they could be run at lower pressure and thus length
BUT if they are rolling sleeve as indicated above by Graeme load rating will change little inspite of height - hmmmmmmmm

I think I need to get my hands on a strut!!!

More thinking
Steve