Quote from: LarryC on July 14, 2012, 07:49:58 PM
M's comment about air shock reaction: 'Push on the cylinder rod with one unit of force and it will collapse one unit of distance.  But push on the cylinder rod with two units of force and it will NOT collapse two units of distance:  it will collapse less.  And considerably less for the third unit of force.  So, nonlinear.

Just to clarify, my comments about an air shock were that they ARE linear.  So if you push on the cylinder rod of an air shock with one unit of force it will collapse one unit of distance.  Push on the cylinder rod with two units of force and it will collapse two units of distance.  And push on the cylinder rod with three units of force and it will collapse three units of distance.

With the ZED it is nonlinear so:  'Push on the cylinder rod with one unit of force and it will collapse one unit of distance.  But push on the cylinder rod with two units of force and it will NOT collapse two units of distance:  it will collapse less.  And considerably less for the third unit of force.  So, nonlinear.'

M.

I will admit I am not familiar with air shocks. In the past I worked on oil shocks, but that`s different. As I see it there are probably two types of air shocks. Type one would be like a bicycle pump with the outlet hole blocked up. So this would be non linear, you are simply compressing air progressively. A similar technology is used for the suspension of semi-trailers on tractor-trailer rigs. This consists of air bags, just like Wayn`s Firestone bellows. Here they act as just a spring, a separate oil type shock absorber being used.
        The only type of air shock that I could envisage that would have a linear response, would work on the same principle to an oil shock . Here, air would be forced by a piston from one chamber to another through a small hole . A separate spring would be needed.
      Actually, I have just remembered a type of linear air shock that I came across. These are used on some front loading washing machines. The drum assembly hangs on two springs, and has air shocks at the bottom. These are like a bicycle pump with a closed outlet. The piston [ which does not incorporate a valve like a bike pump] is deliberately made to be a leaky fit in the cylinder. So it is linear, and more effective at higher frequencies of vibration.

Quote from: mondrasek on July 14, 2012, 09:12:09 PM
Just to clarify, my comments about an air shock were that they ARE linear.  So if you push on the cylinder rod of an air shock with one unit of force it will collapse one unit of distance.  Push on the cylinder rod with two units of force and it will collapse two units of distance.  And push on the cylinder rod with three units of force and it will collapse three units of distance.

The above is not correct.  An air shock force vs. displacement is NOT linear.  Sorry if I confused anyone.

M.

Please see the attached spreadsheet. It shows the main reason that the Travis system has less lift force than the Hydraulic Cylinder at 4.8 PSI.

On the right, note the Total force of the Travis system of 3777 (bright green)  after the system in lowered to 4.8 PSI by lowering the water level. It is greater than the hydraulic cylinder of 3678.

On the left, it shows the Total force of the Travis system of 2630. This is due to the fact that the water around the pod has been lowered so that it cannot support it own weight and sinks to the bottom. Compressed air has been pumped in to maintain the original PSI on the layers. Only the risers are now applying the lift.
   
I hope this helps clear up as to why the Zed works as shown in the attached  'Non Linear ZED advantage over Hydraulic Cylinder'.


Thanks to Wayne for clearing this up.

Edit: 'Compressed air has been pumped in to maintain the original PSI on the
layers' missing statement was added.


Regards, Larry

@All who is downloading the Travis water height calculator. Sorry, but a save error has occurred and my changes wasn't saved. I'll correct and post later when I figure out what happen. Thanks for the patience.

Regards, Larry