Suspension Systems

[simonr]

I've got a load of sketchs but no scanner otherwise I'd ping a couple up

Why not take a photo of the page? Works almost as well as a scanner.

Si

[will_warne]

Why not take a photo of the page? Works almost as well as a scanner.

Si

Si, here's a couple of old drawings from about Feb time (I've made some major changes to the chassis and I was still thinking about a doble wish bone setup). The design's moved on a bit since then but pretty much every drawing since has been quick, scrappy, sketches of particular areas. It gives an idea, though. The main areas I've now changed is a wider cabin over the control arms (will give a little more space and bring width down slightly), changed over to swing arms and I'm now making the side diffs load bearing (they'll basically be in short axle casings mounted to the frame with bushes and the control arms will e mounted directly to them) rather than mounted rigidly to the frame. Engine / gearbox configurations are still up in the air.

Quality's not great as its a mobile camera but it gives an idea.

[bill van snorkle]

Si, here's a couple of old drawings from about Feb time (I've made some major changes to the chassis and I was still thinking about a doble wish bone setup). The design's moved on a bit since then but pretty much every drawing since has been quick, scrappy, sketches of particular areas. It gives an idea, though. The main areas I've now changed is a wider cabin over the control arms (will give a little more space and bring width down slightly), changed over to swing arms and I'm now making the side diffs load bearing (they'll basically be in short axle casings mounted to the frame with bushes and the control arms will e mounted directly to them) rather than mounted rigidly to the frame. Engine / gearbox configurations are still up in the air.

Quality's not great as its a mobile camera but it gives an idea.

Will, that vehicle pictured is extremely short. How's its climbing performance?

If you decide to use Ferret parts the epicyclic reduction hubs are worth looking at. I believe both they and the wheel rims are lightweight Magnesium alloy.

Bill.

Sorry wrong pic. I'm referring to the Ladoga rig.

[will_warne]

Will, that vehicle pictured is extremely short. How's its climbing performance?

If you decide to use Ferret parts the epicyclic reduction hubs are worth looking at. I believe both they and the wheel rims are lightweight Magnesium alloy.

Bill.

Sorry wrong pic. I'm referring to the Ladoga rig.

Bill, I've only ever seen photos and short video clips of it. I think the idea is simply to be as good a winch deployment vehicle as possible.

I've not had a whole hub off a Ferret although I have had a wheel off a few times - light is not a word that springs to mind The run flats don't help but they're still beefy rims. That reminds me of the time my co-driver was inside one of the ferret this friend of mine owns. I'm standing by the spare wheel and he's fiddling arround and asks "Will, I wonder what this handle does?" I go and stick my head in through one of the hatches to see what he's on about but before I can he's pulled the lever which dropped the spare wheel and escape hatch out of the side of the hull. Not one of his clever moments

[Corrode Finger]

Will,

In the lower sketch, is that a swing arm?

I assume that it is mounted at the end of a chassis leg to allow the wheel to be fixed for for and aft movement but pivot up and down, i then assume that the driveshaft from a fixed diff would run down to the end of the 'swing arm'?

From my limited knowledge, that looks like a trailing arm set up?

It looks remarkably similar to the setup on the rear of a sierra, but more refined?

I can see that making an alternative arrangement on the rear could work, but the front puzzles me, and i geuss thats the problem?

[bill van snorkle]

No idea but I know LR built an Indy Series (no, really) to test it out and found it was no better than standard (and presumably had more bits to make / go wrong) was it because the Austin Gypsy was indy or something like that? It was definitely in response to a rival vehicle anyway. There was an article in one of the comics ages ago about it, had some piccies of the setup and details of the performance.

It would have only taken 5 minutes of offroad testing of an independant suspension Austin Gipsey for even LandRover engineers to realise that vehicle was no competition. They were absolutely useless offroad. By contrast the later all leaf sprung Gipsey, a model which I once owned was mechanically superior in almost every sense to the contemporary Landy.

Bill.

[simonr]

Will, have you considered how much torque your drive pods are going to experience at the chassis end, both trying the roll such that the camber changes and rotate such that the track changes?

Have you seen these? Intended for turn-table applications with very high compressive strength - they could make a good shoulder joint.

Si

[will_warne]

Will, have you considered how much torque your drive pods are going to experience at the chassis end, both trying the roll such that the camber changes and rotate such that the track changes?

Have you seen these? Intended for turn-table applications with very high compressive strength - they could make a good shoulder joint.

Si

Hmmm, they're rather rather smart - I like the look of those.

Yes, loading's a concern that I have at the moment - I'd really like to know what sort of load swivels are designed to work at and how much it takes them to fail. I'm still trying to assess the options to to try and get something that's going to be strong enough, is fairly simple and won't be a total headache to make and put together. When I get a chance I may start trying to find a Pinzgauer or Halflinger (maybe a little on the light side and I'm not sure the setup's the same as the Pinz) as my drive setup is pretty much what they do but turned through 90 degrees. One problem may be that their joints might not have flex - I'd be looking for about 25 degrees or so.

[Superpants]

Although based around a substantially similar design, there are some significant differences between the Haf and the Pinz. The Haflinger uses a CV arrangement (and a second one for steering at the front) just outside the centre tube rather than the swing axle and double crown wheel diff of the Pinz. I have the Haflinger parts book and am willing to scan the odd page of the axles if it is of interest?

Although briefly mentioned before, there are some interesting hydraulic systems around. The one that seems to be most developed is by Kinetic in Australia, part of Tenneco. Unfortunately the website doesn't appear to be working correctly at the moment.Kinetic

I understand that this company have demonstrated their system on defender, but can't find any pictures of it on the web so far. It is listed that it is fitted as an option on 2004 Lexus GX 470 SUV if you could find a scrap one for parts!

I am led to believe it will give similar benefits to an air system (eg semi-mimicing a beam axle on an independent setup if a cross linking valve is used), and if the correct valving is used then it can be used to tailor roll control. It is obviously less vulnerable to stone damage and probably more importantly needs a much smaller packaging space than the equivalent air system. If hydraulic accumulators are used, then you will also get a springing effect, so with the right setup could do away with both spring and damper. Whether we ever see this on a volume produced car remains to be seen, but could open up some interesting possibilities (cue tinkering from Simon )

[bill van snorkle]

Although based around a substantially similar design, there are some significant differences between the Haf and the Pinz. The Haflinger uses a CV arrangement (and a second one for steering at the front) just outside the centre tube rather than the swing axle and double crown wheel diff of the Pinz. I have the Haflinger parts book and am willing to scan the odd page of the axles if it is of interest?

Although briefly mentioned before, there are some interesting hydraulic systems around. The one that seems to be most developed is by Kinetic in Australia, part of Tenneco. Unfortunately the website doesn't appear to be working correctly at the moment.Kinetic

I understand that this company have demonstrated their system on defender, but can't find any pictures of it on the web so far. It is listed that it is fitted as an option on 2004 Lexus GX 470 SUV if you could find a scrap one for parts!

I am led to believe it will give similar benefits to an air system (eg semi-mimicing a beam axle on an independent setup if a cross linking valve is used), and if the correct valving is used then it can be used to tailor roll control. It is obviously less vulnerable to stone damage and probably more importantly needs a much smaller packaging space than the equivalent air system. If hydraulic accumulators are used, then you will also get a springing effect, so with the right setup could do away with both spring and damper. Whether we ever see this on a volume produced car remains to be seen, but could open up some interesting possibilities (cue tinkering from Simon )

The Kinetic system has been around for so many years and has promised so much, yet hardly any 4x4 manufacturer has taken it up. I know the Mitsu Dakar cars have it and their results speak for themselves, but i wonder why LandRover never took it up for the Disco and Rangey if it was so good all round rather than the fiddly and temprermental air suspension they have now.

The Pinzgauer swing axle trunnions must be rather special in that they must cope with loading in all directions as they do not employ any additional longditudal control arms or tie bars to prevent each wheel station from being pushed for/aft when hitting obstacles.

Bill.

[will_warne]

Although based around a substantially similar design, there are some significant differences between the Haf and the Pinz. The Haflinger uses a CV arrangement (and a second one for steering at the front) just outside the centre tube rather than the swing axle and double crown wheel diff of the Pinz. I have the Haflinger parts book and am willing to scan the odd page of the axles if it is of interest?

Although briefly mentioned before, there are some interesting hydraulic systems around. The one that seems to be most developed is by Kinetic in Australia, part of Tenneco. Unfortunately the website doesn't appear to be working correctly at the moment.Kinetic

I understand that this company have demonstrated their system on defender, but can't find any pictures of it on the web so far. It is listed that it is fitted as an option on 2004 Lexus GX 470 SUV if you could find a scrap one for parts!

I am led to believe it will give similar benefits to an air system (eg semi-mimicing a beam axle on an independent setup if a cross linking valve is used), and if the correct valving is used then it can be used to tailor roll control. It is obviously less vulnerable to stone damage and probably more importantly needs a much smaller packaging space than the equivalent air system. If hydraulic accumulators are used, then you will also get a springing effect, so with the right setup could do away with both spring and damper. Whether we ever see this on a volume produced car remains to be seen, but could open up some interesting possibilities (cue tinkering from Simon )

The Kinetic system has been around for so many years and has promised so much, yet hardly any 4x4 manufacturer has taken it up. I know the Mitsu Dakar cars have it and their results speak for themselves, but i wonder why LandRover never took it up for the Disco and Rangey if it was so good all round rather than the fiddly and temprermental air suspension they have now.

The Pinzgauer swing axle trunnions must be rather special in that they must cope with loading in all directions as they do not employ any additional longditudal control arms or tie bars to prevent each wheel station from being pushed for/aft when hitting obstacles.

Bill.

Exactly why I'd like to have a look inside them

Superpants, that'd be great as it'd allow me to see if they'd make a suitable donar vehicle.

I've had an eye on active suspension for a while now and it shows a lot of potential - I remember discussing this with Si a while ago when thinking about forced articulation. I've not got round to really looking at it yet as I've been concentrating on trying to come up with a drivetrain that'll work first.

[simonr]

I did have a go at a kinetic style hydraulic setup - just a ram with a bypass between the two ports with a variable orifice to set the damping. The bypass tube connected to an accumulator (a can mostly filled with air). You vary the amount of oil to change the spring rate, the pressure of the air to change the height and rate and the orifice to change the damping.

This, as it happens, is more or less how the fox air shocks work, except the gas forms an emulsion with the oil and it uses internal valving for the damper.

Kinetic just control the air pressure and or oil pressure/volume to taylor the suspension characteristics to the operating conditions.

The issue I had with my air suspension was just trying to generate compressed air fast enough. The air-con compressor chucks out 10cfm at 3000 rpm (engine rpm), but when the suspension was being most active (dynamically controlling roll and wheel ground pressure) it used so much air that it could only keep up if driving at a slow walking pace!

The reason I did not pursue the hydraulic option was that I calculated that with the biggest PTO driven pump I could reasonably run, it would still only cope with 10mph.

A half way house was using the ram to move the position of the top spring mount up & down. You still run in to the problem of insufficient flow for driving fast - but at least if the whole thing fails, it just becomes a regular coil sprung vehicle.

The problem with all the above is that there are occasions when you need to use momentum to clear an obstacle where there is simply not enough grip regardless of the number of lockers or what the suspension is doing. None of the above can keep up and this lag between the terrain and the response actually gives you less traction.

That's where the telescopic spring idea came from. I reasoned that the most important thing was trying to keep the wheels pressing on the ground. If I could live without the self leveling and stuff - there was a technology which reacts almost immediately, is simple and uses no power. The spring!

I tried replacing the ram with a spring - and found it worked better under most circumstances principally because there was no delay and no upper speed limit.

There are other issues with air or hydraulic systems. The main one is that the spring rate changes with compression (and pressure). This means that the damping required for a given mass of vehicle also needs to change with height. Such dampers are available - but are f^2 expensive! On my air setup I found the dampers only really worked well with a bag pressure of 130 psi. That was fine, except it equated to the equivalent of a 5" lift!

I'm much happier with plain old springs!

Si

[Superpants]

Will- I’ll get the scans sorted out, however it won’t be until next week as the parts book is at home and the scanner is at work.

Haflinger Technik have a number of ‘rusty’ axles and chassis that would be suitable to play around with. I have been thinking about building some sort of Haflinger based buggy for some time (hence buying the parts book). I preferred this over a Pinzgauer base largely due to the availability of cheap chassis components. One of the major advantages with the Haflinger is that it is so light, so has a very low ground pressure (something that doesn’t seem to have been mentioned so far (unless I’ve missed it)).

I think you will struggle to source the parts at reasonable prices if you want to use Pinz parts- there is a limited supply of secondhand parts in the UK imported from Switzerland.

Simon- Interesting to know why you dropped the air idea! I think I have some more comments to make, but it may have to wait until I have a bit more spare time to reply!

[bill van snorkle]

Will, I wonder if you could track down a scrapped one of those Netherlands Army DAF 4x4 command car/light artillary tractors of the 1950's/ 60's/70's. The ones that had a spare wheel on each side mounted on stub axles midwheelbase, I think they had a "H'' driveline very similar to what you are planning.DAF built many of their military 4x4 and 6x6 offroaders like this. I could have bought a nice 4x4 over here a few years back for about AUS$5000. Considering it was the only one in OZ at the time it wasn't a bad price, as the more common Ferrets were and still are bringing around $6500.

Bill.

[will_warne]

Will, I wonder if you could track down a scrapped one of those Netherlands Army DAF 4x4 command car/light artillary tractors of the 1950's/ 60's/70's. The ones that had a spare wheel on each side mounted on stub axles midwheelbase, I think they had a "H'' driveline very similar to what you are planning.DAF built many of their military 4x4 and 6x6 offroaders like this. I could have bought a nice 4x4 over here a few years back for about AUS$5000. Considering it was the only one in OZ at the time it wasn't a bad price, as the more common Ferrets were and still are bringing around $6500.

Bill.

I'll keep an eye out Bill.

Superpants, that'd be great. No problem about the time, I'm too busy to really look at them in detail for annother week or so anyway. I found Halflinger Tecknic yesterday while googling and it shows some potential. My only concern may be strength - they're a light vehicle and although I'm aiming to be pretty light its going to be a few hundred kg over a fully loaded Halflinger, will have far bigger boots and rather a lot of power. However, if the price is right it may well make sence just to have a play.

Simon, the idea of using a ram to move the top mount is fairly popular in Auz / NZ at the moment and seems to be a fairly neat solution.

[Tom A]

While I wish that there was an exciting alternative to boring old beams, they are probably the best form of suspension for low-speed off roading, particular in portal or de-dion incarnations to get those diffs out of the way. As you can see from the pictures of me trying to put that red Pinz on its roof while attempting a trials section laid out for LandRovers, Pinzgauers are best at going quick over marginal terrain, and rely heavily on diff locks and bravery to go over anything seriously lumpy. Their high CoG and limited travel can make them look pretty stupid if you drive at things as you would a Land Rover; at least that's the excuse I like to use :-) Will, if you're still interested in seeing the dirty bits of a Pinz axle, I'll post some pics on Monday.

Undoubtedly, given large sums of money and active suspension, an independent can be made to act like a beam at low speeds but why not just use a beam in the first place? I'm afraid these fine gentlemen have done some extravagant beard stroking and concluded the same thing:

"SAE Technical Papers

Title: Independent Versus Axle Suspension for On/Off Road Vehicles

Document Number: 921662

Author(s):

D. A. Crolla - University of Leeds

G. R. Firth - University of Leeds

D. N. L. Horton - University of Leeds

Abstract:

The conflicting suspension requirements of vehicles which are designed for both on and off-road operation are examined. The example vehicle used throughout the calculations is a six-wheel truck of 24 tonne GVW and is based on an existing crash tender design. Using the vehicle dynamics analysis software (VDAS) package, the ride and handling behaviour of the truck is analysed for two versions of the vehicle; one with three axles suspended on lead springs with a bogie arrangement at the rear, and another with independent wheel suspension throughout.

The overall conclusion drawn is that axle designs have significant advantages for off-road vehicle applications; they maintain good ground clearance, they are based on inexpensive, well proven technology and, with attention to detail deisgn, offer vehicle dynamic performance comparable with independent designs. On the other hand, if the optimum ride and handling compromise for on-road conditions is a priority, then the independent suspension may be worth the additional investment. "

Anyway don't let me or the beard strokers stop you trying, innovation is good.

[simonr]

Oh well.....Maybe I'd better just give up then.

Si

[will_warne]

While I wish that there was an exciting alternative to boring old beams, they are probably the best form of suspension for low-speed off roading, particular in portal or de-dion incarnations to get those diffs out of the way. As you can see from the pictures of me trying to put that red Pinz on its roof while attempting a trials section laid out for LandRovers, Pinzgauers are best at going quick over marginal terrain, and rely heavily on diff locks and bravery to go over anything seriously lumpy. Their high CoG and limited travel can make them look pretty stupid if you drive at things as you would a Land Rover; at least that's the excuse I like to use :-) Will, if you're still interested in seeing the dirty bits of a Pinz axle, I'll post some pics on Monday.

Undoubtedly, given large sums of money and active suspension, an independent can be made to act like a beam at low speeds but why not just use a beam in the first place? I'm afraid these fine gentlemen have done some extravagant beard stroking and concluded the same thing:

"SAE Technical Papers

Title: Independent Versus Axle Suspension for On/Off Road Vehicles

Document Number: 921662

Author(s):

D. A. Crolla - University of Leeds

G. R. Firth - University of Leeds

D. N. L. Horton - University of Leeds

Abstract:

The conflicting suspension requirements of vehicles which are designed for both on and off-road operation are examined. The example vehicle used throughout the calculations is a six-wheel truck of 24 tonne GVW and is based on an existing crash tender design. Using the vehicle dynamics analysis software (VDAS) package, the ride and handling behaviour of the truck is analysed for two versions of the vehicle; one with three axles suspended on lead springs with a bogie arrangement at the rear, and another with independent wheel suspension throughout.

The overall conclusion drawn is that axle designs have significant advantages for off-road vehicle applications; they maintain good ground clearance, they are based on inexpensive, well proven technology and, with attention to detail deisgn, offer vehicle dynamic performance comparable with independent designs. On the other hand, if the optimum ride and handling compromise for on-road conditions is a priority, then the independent suspension may be worth the additional investment. "

Anyway don't let me or the beard strokers stop you trying, innovation is good.

Tom, yes, I'd really like to have a look to see what they do on a Pinzgauer. Although I may end up using some parts the setup will be very differant and I won't be having problems with lack of travel!

The main reason for going down a route like this is to gain ground clearance (there will be a lot of this), reduce weight (1500 kgs with all the kit on board including driver and co-driver is the aim) as well as offering better handing at speed (the vehicle will be designed to go quickly when required). True it'd probably be easier to build annother beam axled truck but I'd like to try and see if I can make something else work as I think potentially it could be extremely capable. This isn't going to be a quick or cheap project by the time its finished but I'm prepared for that.

[Corrode Finger]

Oh well.....Maybe I'd better just give up then.

Si

If you were that way inclined, i doubt that X eng would be around?

You just got to keep at it, you have come so far, as you said to me when this thread started, innovation is good!

[bill van snorkle]

Keep plugging away Simon. Most worthwhile innovations come from enthusiastic small time underfunded individuals like yourself thinking outside the box anyway. When was the last time anyone saw a British made truck in the Euro truck trials ?If the study that Tom has referenced was undertaken in Germany, Russia, Sweden etc I would place some stock in the conclusions arrived at. With all due respect to most of the members of this board, the beard strokers are ''British automotive engineers''. Now I'm not going to say that certified British auto engineers aren't capable of designing world beating crosscountry vehicles,but it does seem that in order to gain an engineering degree and secure a job in the vehicle manufacturing industry in Britain, one must also successfully complete a course in penny pinching bean counting.Whilst in other countries they are allowed to be engineers. Many other vehicle building nations have runs on the board, re Berliet,DAF,MAN, Merc Benz,Tatra, Volvo,Kamaz etc etc in producing extreme capability crosscountry trucks,but sad to say I cannot recall any British crosscountry truck in history that I would give garage space to. I used to think Scammel Explorers and Alvis Stalwarts were desirable, but my research on those has revealed many deficiencies in many areas from a crosscountry capability viewpoint.

bill.

[simonr]

Sorry, there should have been a " " after that!

Si

[Superpants]

I have scanned in a few of the pages from the haflinger parts book, showing the major suspension lumps. I hope that they are of interest. They are indeed quite light duty compared to what we are used to on Land Rovers!

Haflinger_front_hub_assembly.pdf

Haflinger_front_suspension.pdf

Haflinger_main_sub_assemblies.pdf

Haflinger_rear_axles.pdf

Haflinger_rear_hub_assembly.pdf

[will_warne]

I have scanned in a few of the pages from the haflinger parts book, showing the major suspension lumps. I hope that they are of interest. They are indeed quite light duty compared to what we are used to on Land Rovers!

Cheers for that. Hmmm, they probably are a bit on the light side; the big problem would be making CVs strong enough (they don't look very big and I won't have drop boxes...

Its food for thought, though.