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daddylonglegs wrote:Ben, my friend who I lent my suspension book "New directions in suspension design" is away at this time so I cannot quote directly from the aticle on Ackerman linkage, but they basically said that Ackerman got it wrong because when he did his calculations he did not factor in Slip Angles of the wheel/tyre units when making a turn. They concluded that it makes more sense to have parallel steering or even Reverse Ackeman angles. After reading that I tried it, liked it and haven't looked back.
Very interesting Bill. An ISBN for that book would be great when your friend gives it back.
Yes Ben I like the idea of the powered trailer concept. I have been thinking about shortening my current vehicle down to say 80 inch wheelbase, lopping off the overhang and building a short hinged rear section that articulates only in pitch and roll, but not yaw as it would be a nightmare to reverse down steep fire trails after the unlikely event of a failed climb. I don't know yet if I would make the rear axle steerable, but that would be one way of using up my bolt on 101 swivel housing/CV joint assemblies, and it would certainly make it more manouverable, but could probably acheive better resuts with steering brakes.
Because I have used up my PTO facility with the crawler box I would have to drive the "trailer'' in the same manner as the old 6x6,but thats no biggie. The only shortcoming I see is that to keep front and rear overhangs to a minimum, the ''trailer'' would only be a little over 1 metre long if running 36 inch diameter tyres.
Bill.
daddylonglegs wrote: building a short hinged rear section that articulates only in pitch and roll, but not yaw as it would be a nightmare to reverse down steep fire trails after the unlikely event of a failed climb. I don't know yet if I would make the rear axle steerable, but that would be one way of using up my bolt on 101 swivel housing/CV joint assemblies, and it would certainly make it more manouverable, but could probably acheive better resuts with steering brakes.
What I was thinking of is having a trailer where yaw (if that is what you are calling sideways movement) is controlled by a hydraulic ram or some other sort of steering mechanism. So while the rear axle is not steerable, you can "steer" the connection between the truck and trailer to make it track correctly when reversing (or lock it straight), and to help it corner more tightly.
Oh and you should sell the bolt on 101 swivels and CV's to me so I can build the axles for my "improved" forest rover.
Hi Nick,Have a good trip, and if you need someone to look after your Roadless while you are away, just ship it over here and I will be happy to oblige.
Bill.
I think it is time to bring this thread back from the dead...
I have been having some crazy ideas (not that that is anything unusual) on how to build something that looks like a Forest Rover, and can safely handle big wheels, etc. Of course building a replica as close as possible to the original would be best, but finding decent (and available) planetary hubs seems to be the hardest part.
The Forest Rover had an overall axle reduction of 12.96:1 The BW1339 ratio of 2.57:1 multiplied by a 4.7:1 axle ratio, gives 12.1:1. Now I know the BW1339 is not strong enough to be used as a hub reduction planetary (hub reduction would be best as it lowers the load on the axles), however it can give the overall gearing needed if strong enough standard type axles can be built. Surely it would be possible to either build 35 spline Sals/d60's, or get some big truck axles with about 5:1 diffs, that could cope with 50" wheels.
If you are reading this Bill, I think you saw the video of Dan Dibble and his big heavy buggy with a 454 beating the hell out of his 44" boggers and rockwells. Before he built the buggy, Dan used to run 35 spline 7.17:1 D60's front and rear, with similar sized tyres and a big motor. And he has always driven the same. He did have a few R&P failures, but you have seen the way he drives so I'm not surprised - and he attributed most of the R&P failures to lack of oil/overheating.
Now of course if you were using the BW1339 almost permanently engaged it might shorten its life. What do you think Bill? So who thinks I am crazy for considering doing it this way???
Maybe there are some new planetary hub assemblies that can be obtained for reasonable prices and adapted??? Have a look down the bottom of the page - probably far too big and heavy for the FR application though.
Ben, i have been trying to think of an excuse to resurrect this thread too. The photos Brad posted on Pirate have got my interest all fired up again.
I think for the relatively limited use a Forest Rover type vehicle would see,the 1339 would hold up quite well . They really are a very robust unit. in fact I wouldn't discount them as being suitable for hub reduction duties either, except for availability maybe. Fancy the Americans ordering their Jeeps without the low range option ! I have been thinking that with positively located front and rear axles (one link or torque tube style) that eliminated axle tramp and adhering to the original formula of modest engine and low gearing for tractive effort, you should be able to getaway the Dana/ Salisbury type assemblies. From asking a couple of oldtimers in the logging industryThe C1600 4x4 International Dana70 fronts appear to be able to handle 12.00 x 20's reasonably well with crude suspension on a considerably heavier vehicle than a LandRover.
Bill.
Ben , I am afraid that any reduction hubs I use would have to be second hand and cheap. Strangely enough, I have been unable to find any firm in Melbourne that wrecks 4wd tractors. If I could get a couple of Zetor or similar front drive axles cheap and adapt brakes to them the project could be completed very quickly.
Bill.
Hi Bill, second hand and cheap sounds good to me too. The reasons I haven't more actively pursued this are that:
To build even a 35 spline rear Salisbury is about $3000 with axles and locker.
$800 Stub axles
$800 Axles and Drive Flanges
$1300 (approx) locker (ARB or JM)
Then to build a front axle is at least another $3000 if not more.
The 30/30 spline longfields and aftermarket 30 spline axles are supposed to be as strong as a stock D60 front axle, which could reduce costs a bit, but even then it would be $$$ and you would still need to either run 101/JM stub axles or trust the strength of bored std stubs (which I definitely wouldn't do with 50" wheels). The D70 front you mention would only be about the same strength or even weaker in terms of axle strength - but may be cheaper if one can be found for the right price - but then you have to match front and back ratios...
The cheapest option would definitely be to find some cheap 2nd hand hubs and do the machining adaption myself. Do you seriously think the BW1339 would hold up if I could find 4 for the right price??? And essentially I would have to throw away the cases and make the hub assembly wouldn't I? The inner shaft is 10-spline isn't it? Is that the same as the Rover axle 10-spline and could the gear it goes into it be broached to 24 spline???
Hi Ben, The one thing that turns me off using straight heavyduty truck axles is that i didn't want the vehicle to end up as just an Australian version of the steriotypical US "Monster truck'' which frankly have never interested me,and would probably stand no chance of being approved for road registration in any state of Aus.
I do really believe the BW 1339 would be actually stronger than the reduction units on the original Forest Rover as the sun gear and planetary gears are larger in diameter and I would not bother to alter the ten spline input shaft which is the same diameter as an Lt230/ R380 mainshaft and a little larger than the old 10 spline axles. The 2.57 reduction should reduce the stress on the input shaft enough to make this size viable. The diameter of the output shaft could be anything you can fit inside a spindle up to 70mm .( Diameter of 1339 output spline)Because the 1339 uses helical instead of spur gears the transmission efficiency would not be as high but it may not be too great a difference. Seeing as how you would have to make a new case, some of the other American planetary tranfercases should also be suitable for hub reduction and it would also be easier to source enough of them.
Bill.
Looks like Mitsubishi have a unit too. Who can read Japanese?
/
Gday Ben,
My Japaness sucks! but....
As for the axle which catches the weight item securely, on the front I type section, the Takanobu asking/depending design which adopts cast iron make バンジョウ type on the rear. The travelling stability whose wide-tread is high is brought. In addition, as to shackle link system it converts anew, adopting front suspension, the long tapered leaf spring. By the fact that the long tapered leaf spring is adopted, riding comfort and durability have improved even in the rear suspension which adopts the trunnion suspension which is superior in reliability.
daddylonglegs wrote:Hi Ben, The one thing that turns me off using straight heavyduty truck axles is that i didn't want the vehicle to end up as just an Australian version of the steriotypical US "Monster truck'' which frankly have never interested me,and would probably stand no chance of being approved for road registration in any state of Aus. I do really believe the BW 1339 would be actually stronger than the reduction units on the original Forest Rover as the sun gear and planetary gears are larger in diameter and I would not bother to alter the ten spline input shaft which is the same diameter as an Lt230/ R380 mainshaft and a little larger than the old 10 spline axles. The 2.57 reduction should reduce the stress on the input shaft enough to make this size viable. The diameter of the output shaft could be anything you can fit inside a spindle up to 70mm .( Diameter of 1339 output spline)Because the 1339 uses helical instead of spur gears the transmission efficiency would not be as high but it may not be too great a difference. Seeing as how you would have to make a new case, some of the other American planetary tranfercases should also be suitable for hub reduction and it would also be easier to source enough of them. Bill.
Interesting thoughts Bill. I too do not want to build something like the US trucks - since I prefer to drive obstacles as slowly as possible, rather than lots of right foot - which sems to be the case in the US from most of the videos I have seen. I would prefer something like the roadless, which has stock height suspension, and is more like a tractor capable of a decent top speed than anything else. Actually one other problem besides the reduction boxes would be getting tyres that are decent on the road and a sensible width. All the tyres used on the us trucks that are around 50" are crazy widths like 13" or 15", not 10" or 11" like the forest rover's wheels. And truck/earthmover wheels will probably be far too stiff to fley properly. Have you seen anything suitable?
With regards to the planetary boxes - why couldn't the planetary be mounted directly to the outside of the hub (where the drive flange mounts on a LR hub - with the outer ring gear of the planetary fixed to the hub), and drive it that way, so only the narrow 10-spline shaft has to pass through the spindle/stub axle. If you are running big rims/hubs/brakes like the forest rover (and not the landrover pattern) then the overall size of the hub/reduction box will not be a problem for the wheel to fit over. Forgive me if you were suggesting this already - but I got confused when you started talking about an output shaft.
I just realised Bill, that the planet gears need to be held stationary for my idea to work, and I can't work out how to do this. Also, it looks from the pics of the BW1339 that it is designed so that the ring gear is held stationary and the sun and planet gears provide the drive - is that right? So the ratio would be different if you were using the ring gear to drive thw wheel/hub.
Hi Ben, The way I understand it , for a reduction hub to work, something in the planetary geartrain must be held static to the spindle. This could be the internal ring gear as in Leylands, Mercedes , Man's etc, or the planetary gear carrier, as in the Ferret scout car. The one concern I had years ago when I cut down the Leyland reduction units, apart from weight, was that the spindles would be subject to high torsional loads and trying to work out the compromise between adequate input shaft (axle from diff to sungear) size, and a spindle with enough cross sectional area to resist being twisted off under full torque. I also toyed with the idea of making the reduction units 2 speed by sliding the sun gear out of mesh with the planetary gears and locking it directly into the outer hub casing for direct drive. this would have allowed me to run conventional 35'' tyres at only ring and pinion ratio or 48-50 inch tyres at ring and pinion ratio x 4:1. The Landy with huge wheel openings for 50 inch tyres would have looked a bit silly on 35's though.
I went to Elmore Field Days a couple of weeks ago and the trend seems to be heading towards faster tractors in all classes so adequately speed rated tyres in most of the popular sizes are becoming available . The best tractor on display IMO was the JCB Fastrac which looked like an oversize 4wd hotrod on big equal size high speed tractor tyres,reduction hubs coil springs front and back , disc brakes allround and a luxurious cab that would put a p38 RangeRover to shame. It had a towing capacity of 30 tons and a top speed of 80kmh. I really wish JCB had bought LandRover all those years ago instead of BMW and now Ford.
So the planet gears can be fixed to the outer end of the spindle/stub axle, and the ring gear fixed to the hub. Would this give the same ratio as 2.57:1 or a different ratio???
Another option for tyres would be an off-road truck tyre. The dunlop SP931 is 11.00x22.5 (about 45") has 25mm deep tread!!! and is probably legally regroovable (so you can change the tread pattern however you want).
I think something like this might work better in the less muddy more rocky terrain we have in QLD (but you may want to make the gap between the lugs wider. It looks a bit similar to a michelin XCL.
Yes Ben, if you fixed the ring gear to the spindle and the planet gear carrier to the hub you would get 2.57:1.
10x00x28 tractor tyres are considerably lighter than the equivelent size truck tyre. I was thinking a grass type tractor tyre would be more suitable for the drier conditions of QLD.
bill.
The grass tractor type tyres are all really wide and it is almost impossible to find one with a 50" diameter. What tyres were fitted to the 80kmh tractors you mentioned? All the bar-tread tractor tyres I can find are only speed rated to 20mph. Tyres for a 28" rim do not seem very common these days either.
Ben The JCB tyres were much too big and wide but there were quite a few smaller tractors at the field day and 50kmh capability was quite common. But I was on a mission with work and couldn't spend as much time at the tractor venue as I would have liked.
Bill.
Really sorry that I have'nt got the pics of the axles done for you yet; it was on the cards for yesterday.....switched computer on to unload camera, & a hiccup which had emerged the night before now seems to have become a catastrophic H/D failure.....so am currently on a borrowed
computer......which is not set up for pics.....
Been a nightmare of a past few months, so have'nt had time to participate lately....
Photos are taken, hopefully be resized tonight.....will try to get them uploaded, but as we are only on 4 hrs power a night......may have to be tomorrow...
....Round & round in ever-decreasing circles, really....!!
(We were 3 wks in UK in September, but we are just flat out here on the farm now.....
Got a tray on the back of the Dodge now....still got to do sides, & finish it off, but its as good as you can get for the money in robust 'twincab utes ' now!! The Luton van body weighed over a ton.....so now it has the unnerving habit of skating when braking.........)
Thats a very helpful offer that John has made (thanks..!), so after a couple of delays, am now in process of sending them to him & I've no doubt he'll post a link when they're up.....
.....We're getting there..!
...Hi....!!
