My old truck on Ebay again....

[garymorris]

Nick , I'm sure there's a lad called shaun in macclesfield that's in to scammell's I think he used to have a sand coloured one

[NRS91]

think ive seen it around... it was a wrecker wasnt it?

im in ellesmere at the mo though its college for the week

[garymorris]

Ellesmere , that's where my workshop is !

[NRS91]

small world eh?

that tescos looks a mess haha

anyway back on topic... do you think the LR axle casing could take the stresses of a built in swinging beam?

also how do you think you could build a swinging beam axle set up using a coiler axle?

imagine a 90 with a swinging beam set up

also why is the 2:1 reduction nessacary for the swinging beam? is it to keep the four wheels planted?

hmmm how about a collaborative lr4x4 project to make these axles?

[Turbocharger]

Night Train - how do you arrive at a 2:1 walking beam ratio required? Not disputing, just interested. I'm guessing the torque reaction around the halfshaft has to be less than the moment going into the walking beam 'box' from the two wheels (to stop the front wheel lifting off the floor and the rearmost wheel climbing under it), but I think this would be much less if the wheels were well spaced, which they necessarily would be because LR wheels are quite large.

I can see that a larger ratio here is better (high speed / low torque would give least torque reaction and would protect the halfshafts more too), but if you could make do with a 1.35 ratio at the walking beam, you could have a 4.77 diff in the front and a 3.54 diff in the rear.

I'm not going to build anything like this but the physics of the mechanism interests me.

[NRS91]

im interested in the operatings too

but it would be nice to have built just out of curiousity... but cost would probs be prohibitive...

what about an axle set? so both axles have the same diff ratio but the front has a portal/sun ring (cant rememeber proper name) reduction

then you wouldnt need the hardend shafts and you would have a pretty bombproof and flexy set of axles with the benefit of 6 wheel drive too

[bill van snorkle]

Anyone here heard of the DAF Trado bogie drive kits from the 1930's 40's to convert mainly Ford cars, light and medium trucks to tandem drive ? It was a complicated and presumably expensive affair which in total employed 7 crownwheels and 9 pinions.They used the original the vehicles original single rear axle assembly and bolted a bevel gear driven walking beam to the end of each axle tube. There was a crownwheel on te end of each half shaft, each of which drove 2 pinions positioned 180 degrees apart. Each pinion drove a short shaft the end of which contained an identical pinion that meshed with another crownwheel to form a 90 degree bevel drive to each wheel. I'd imagine it would be a nightmare to set up all those gear sets for correct mesh patterns, and forget about tracing the source of a noisy diff. http://www.overvalwagen.com/images/daf_ford_trado_wheels.jpg

Bill.

[NRS91]

hmm yea i suppose it would make things alot more difficult if you got things wrong but on the off chance it worked well then you would have an ultra capable truck

would a chain drive be the best way to do it?

how do you make the pivot system for the beam?

[bill van snorkle]

hmm yea i suppose it would make things alot more difficult if you got things wrong but on the off chance it worked well then you would have an ultra capable truck

would a chain drive be the best way to do it?

how do you make the pivot system for the beam?

A simplified explanation on how to make the beam pivot would be to bolt the walking beam housing to a LandRover style full floating hub. The halfshaft instead of attaching to the hub would have a gear or sprocket on the end which would mesh with a train of other gears to each wheel or a chain to a sprocket at each wheel. I believe only road graders employ chain drive. Scammels, Leyland Martians, Engasa Boomerang bogie conversions etc due to the much higher speeds expected from these vehicles all employed gear drive. As proven by motorcycles there is nothing wrong with chain drive for high speeds providing chain tension can be maintained. Bikes however tend to only be powered going forward whereas cars and trucks have reverse gear as well so the tensioner should be effective in both directions.

Bill

[NRS91]

thanks Bill very helpful as usual... if the chain was tensioned like a tak track i assume that that would work?

i dont quite understand the first bit about the hub? im guessin you have a collar on the end of the axle and a bearing with the beam on then have a sprocket/gear to provide drive? am i anywhere near?

ive read alot but never done the practical side much tbh... except the defender front axle and fanbelt on my td5

[Night Train]

I doubt that the LR hub would be anywhere near strong enough to act as a sole pivot for a walking beam gear case. Imagine a case 40" long infront and behind the hub leavering on it when a corner was taken, the hub would pop off the bearings or the stub axle would break. On a real Scammell the gear case is braced back onto the axle tube in board of the leaf spring on a rotating bush.

The need for a 2:1 gear ratio is to counter the driving torque.

On a standard axle the driving and braking torque is transmitted to the chassis via the leaf springs or radus arms and A frames etc.

The walking beam when the brakes are applied would try to do a 'stoppie' and lift the rear wheel rotating the whole gear case around the axle bearings. Under acceleration the same thing would happen and the gear case would try to do a 'wheelie'. The 2:1 gear ratio reduces that to an acceptable amount. A lower ratio would be even better but is impractial.

If I was building a walking beam gear/chain case I would use a bigger axle as a starting point. Maybe something from a 5-7 ton truck with tubular axle tubes. It would be easier to just use a complete walking beam axle from a scraper.

On my 6x6 I used Sailsbury axles made wider by extending the short tube and having long half shafts in each side. The middle axle had a massive A frame welded on with its apex just below the prop shaft flange on the T box and a short prop was fitted. The rear axle was the same but its apex was jut above the middle axle diff. The A frames were located to cross members via a LR110 radius arm chassis bush, the only off the shelf cheap thing I could find. The A frames took care of the fore and aft location and the driving/braking torques to the chassis.

The springs were inverted 680lb/inch leaves that were pivoted on a housing that fitted a LR stubaxle on the side of the chassis. (see images posted earlier by someone else.) The ends of the springs were on suspended shackles to the axle. This allowed the axles to both spring and swing freely up and down. The lateral location was via bearing pads on the chassis in front and behind the spring pivot. The pads stopped the spring from moving laterally and that located the axles quit well. It gave each wheel 12" movement up and down so it could drive over a 24" hump without lifting an axle.

It was more a copy of the rear bogie arangement on a Scammell Constructor.

The front axle was made to match the width of the rear axles and was located with a similar A frame facing back towards the T box. The spring was a pair of LR front springs dismatled and doubled up with the redundent spring eyes cut off. The middle of the spring was on a bearing block on the front cross member so that it could swing freely. The spring was located onto the axle with a fixed eye at one end and a very short fabricated swing shackle at the other end. It gave 18" movement up and down so one wheel could be lifted 36" up with the other on the ground.

The T box was something I designed and made. It used only Series T box gears and cut down shafts and was remote mounted. It had an input flange, PTO output flange, front drive and two rear drives. It was a 3 speed box and had counter rotating outputs so the diffs were upside down. The ratios gave both under drive and over drive.

The Main G box was a ZF 5 speed with a low crawler 1st and direct drive 5th. With the T box the ratios theoretially gave, at 4000rpm, 1.5mph in bottom 1st and 108mph in high 5th. The torque in low 1st wrecked a few props.

[Night Train]

A nice Scammell Constructor on Ebay.

[NRS91]

just a thought

right... if the diff had a 1:1 ratio and a small casing then the 3.54:1 ratio of the Defender diffs was in the walking beam part? also if the pivot point was an inch or two below the level of the wheel hubs then it wouldnt want to kick up at all and the clearance would still be there due to the smaller diff casing

now would a rear axle off an LDV on dualies do the trick you think?

also 40" between the wheel hubs should be enough for a land rover because then you could easily fit 38s all round

do you think you could do a sketch in paint of an ideal axle?

also what kind of grader would have an axle of a suitable size for a landy?

[NRS91]

http://cgi.ebay.co.uk/linnhoff-motor-grade...3A1%7C294%3A200

this the kind of grader?

[Night Train]

Here is a photo of the set up on my 6x6

just a thought

right... if the diff had a 1:1 ratio and a small casing then the 3.54:1 ratio of the Defender diffs was in the walking beam part? also if the pivot point was an inch or two below the level of the wheel hubs then it wouldnt want to kick up at all and the clearance would still be there due to the smaller diff casing

now would a rear axle off an LDV on dualies do the trick you think?

The location of the pivot wouldn't make much difference in real terms as the unloading of the leading wheel is due to the drive torque needing to have something to react against.

I've tried a number of geometries and ratios in Lego Technic and, when push comes to shove with anything less then a 2:1 ratio, under load the walking beam will try to rotate around the axle when the wheel is unable to break traction and spin. It works in the same way as a planetry gear set with the walking beam becoming the cage and rotating with the wheels as planet gears and the ground being the annulus.

I have also looked a DeDion type axle where the walking beam pivots on a dead axle tube and a diff in the chassis connects to the walking beams via CV joints and exposed shafts. The drive input to the gears/chains in the walking beams would still need to at or very near the pivot point of the walking beam though and if the axle tube was designed as an open channel then the flexible drive shaft could still enter the walking beam through the pivot.

Another method would be to have a diff casing with a small gear case attached where the axle tubes were to give two drive flanges as close to the diff as possible. These could then be used to drive flexible shafts that then drive stub axles on a walking beam. This would do away with gears or chains in the walking beam and reduce unsprung weight to something less then half a ton!

For strength the 'dead' axle tube would be able to protrude right through the walking beam to get the bearing as far apart as possible to counter the lateral loading.

Here's the real thing from the Scammell Explorer parts manual. The whole assembly slides onto the axle tube with the spring seat going between the gear case and the reinforcing web.

Just for fun...

[bill van snorkle]

I doubt that the LR hub would be anywhere near strong enough to act as a sole pivot for a walking beam gear case. Imagine a case 40" long infront and behind the hub leavering on it when a corner was taken, the hub would pop off the bearings or the stub axle would break. On a real Scammell the gear case is braced back onto the axle tube in board of the leaf spring on a rotating bush.

The need for a 2:1 gear ratio is to counter the driving torque.

On a standard axle the driving and braking torque is transmitted to the chassis via the leaf springs or radus arms and A frames etc.

The walking beam when the brakes are applied would try to do a 'stoppie' and lift the rear wheel rotating the whole gear case around the axle bearings. Under acceleration the same thing would happen and the gear case would try to do a 'wheelie'. The 2:1 gear ratio reduces that to an acceptable amount. A lower ratio would be even better but is impractial.

If I was building a walking beam gear/chain case I would use a bigger axle as a starting point. Maybe something from a 5-7 ton truck with tubular axle tubes. It would be easier to just use a complete walking beam axle from a scraper.

On my 6x6 I used Sailsbury axles made wider by extending the short tube and having long half shafts in each side. The middle axle had a massive A frame welded on with its apex just below the prop shaft flange on the T box and a short prop was fitted. The rear axle was the same but its apex was jut above the middle axle diff. The A frames were located to cross members via a LR110 radius arm chassis bush, the only off the shelf cheap thing I could find. The A frames took care of the fore and aft location and the driving/braking torques to the chassis.

The springs were inverted 680lb/inch leaves that were pivoted on a housing that fitted a LR stubaxle on the side of the chassis. (see images posted earlier by someone else.) The ends of the springs were on suspended shackles to the axle. This allowed the axles to both spring and swing freely up and down. The lateral location was via bearing pads on the chassis in front and behind the spring pivot. The pads stopped the spring from moving laterally and that located the axles quit well. It gave each wheel 12" movement up and down so it could drive over a 24" hump without lifting an axle.

It was more a copy of the rear bogie arangement on a Scammell Constructor.

The front axle was made to match the width of the rear axles and was located with a similar A frame facing back towards the T box. The spring was a pair of LR front springs dismatled and doubled up with the redundent spring eyes cut off. The middle of the spring was on a bearing block on the front cross member so that it could swing freely. The spring was located onto the axle with a fixed eye at one end and a very short fabricated swing shackle at the other end. It gave 18" movement up and down so one wheel could be lifted 36" up with the other on the ground.

The T box was something I designed and made. It used only Series T box gears and cut down shafts and was remote mounted. It had an input flange, PTO output flange, front drive and two rear drives. It was a 3 speed box and had counter rotating outputs so the diffs were upside down. The ratios gave both under drive and over drive.

The Main G box was a ZF 5 speed with a low crawler 1st and direct drive 5th. With the T box the ratios theoretially gave, at 4000rpm, 1.5mph in bottom 1st and 108mph in high 5th. The torque in low 1st wrecked a few props.

Well yea, as stated I only gave the example of a LandRover hub because most here are familiar with them, and would follow what I was attempting to describe. There are any amount of commercial vehicle rear axle assemblies with strong enough hubs and spindles for the job. I doubt one would need to go as far as using a 5 ton truck diff. That would kill ground clearance unless a boomerang shaped beam was made. A duall wheel Dana 70 rear end would be more than enough and still give the same ground clearance a a Salisbury. The 1 1/2'' diam halfshafts should be easily capable of driving 4 wheels on a vehicle a few hundred pounds heavier than a standard LandRover. I know a DAF Trado isn't a Scammel. But neither is a LandRover. In the photo I linked, and on some of the other photos of Trado Bogies I've seen, there is little evidence of additional bracing of the original axle housing. The Scammel is a heavy vehicle designed to carry weight or drag tank trailers around corners and bends so the substantial extra bracing is warranted on them.

I don't really see the need to match Rover final drive ratios as nothing in the Rover inventory save a FC 101 front end would be really up to the job on such a vehicle, particularly when reversing up hills and out of holes etc.

On your walking beam drawings with LandRover gears, how many gears in each beam did you calculate you would have to use ? The series 1,and 2 low range slider ( the largest of the Rover spur gears)is around 6'' in diameter. Disregarding the minor difference that a 2:1 ratio would make to the gear count, with your 40'' wheel spacing you would need 9 or 10 gears per side, all supported on shafts and bearings. The frictional losses would be quite high I'd imagine.

I feel now that there is a much more practical and conventional way of acheiving Scammel Explorer type articulation by using 2 Volvo C306 middle axle differentials . With a drop box on each diff and the diffs turned back to front, the wheelbase front to middle and middle to rear can be kept nice and short, with relatively long flat propshafts to permit maximum up and down travel of the diffs.

Bill.

Edit. I just noticed your latest post after submitting this one. I have a book titled US Military Vehicles that shows an experimental 8x8 Mack Fire truck described as having

2 so called ''X Drive'' bogies similar I guess to the one on your free hand drawing. I don't know if the vehicle was successful or not though. They don't say.

[NRS91]

just a thought.... again... lol

if you get three rear axles... make one a 1:1 drive ratio and then shorten the other two axles, weld the diffs and put 90degree boxes on either end with a 90 drum brake on each and then bolt one diff on each output of the first axle...

might work if the first axle was a van one and the other two were landy ones

also it wont lemme see you pics

[bill van snorkle]

just a thought.... again... lol

if you get three rear axles... make one a 1:1 drive ratio and then shorten the other two axles, weld the diffs and put 90degree boxes on either end with a 90 drum brake on each and then bolt one diff on each output of the first axle...

might work if the first axle was a van one and the other two were landy ones

also it wont lemme see you pics

I think the DAF Trado Bogie for the Ford cars and lighter trucks pretty much had what you described with the exception of the 1:1 ratio. Incidently, the highest ratio compact differential centre I have ever seen was 1.3:1 off a MAN with planetary hub reduction.

Which photos are you not able to see ? This isn't the Members Vehicles Forum.

Bill.

[NRS91]

the ones posted by night train...

then again the college internet is probs blocking them...ill try again at 8pm

i this what you were talking about?

[Night Train]

Bill, Yeah, big truck axles would be overkill and over size but I was thinking of the stub axle strength primarily.

There probably are lots of axles that could be used as a good starting point but on a personal point I do have a thing about wanting the strongest, toughest transmission so I will go for an over kill.

I did design using a whole train of Tbox spur gears with a spur gear cut off the intermediate gear to make the smaller input gear in the centre. I intended the whole train of gears to run on intermediate gear roller bearings but the friction was going to be really high.

I then thought about chain drive and progressed with drawings for 3/4" and 1" duplex chain with a double sprocket in the centre as the input but that made the walking beam chain case about 6" wide on the inside to cover the two runs of duplex chain.

Calculations with 1" simplex chain showed that it probably wouldn't be strong enough for harsh off road use given the relatively small sprocket size needed to get the 2:1 ratio.

I also though of shaft drive with bevel gear boxes and also skew helical gears inside the walking beams. but cost was going to be horrendous as nothing was 'off the shelf'. Then I even considered hydraulic drive and ideas got really silly.

That is when I began thinking of other ways around having gears or chains as in my free hand sketch and ultimately to just having two axles.

I think my limitations were down to budget, access to engineering machines and lack of real life experience of chain drives.

[bill van snorkle]

the ones posted by night train...

then again the college internet is probs blocking them...ill try again at 8pm

i this what you were talking about?

The first and second photos are Trado Bogies. The 3rd photo if I recall correctly is a more modern 6x6 Daf with the spare wheels mounted on non driven stub axles to reduce the chance of bellying out on hummocks etc. The driveline on that model I think consisted of a single differential and cross shaft behind the transfer case, and individual propshafts going into right angle drives at each wheel. I think it had independant suspension all round but could be mistaken on that count.

To anyone contemplating building a 6x6 LandRover sized vehicle, thinking it could be the ultimate in cross country mobility, I have to state that this is not necessarily always the case. Heavier vehicles such as Dafs, Scammels etc would rarely encounter a situation where they have too much floatation.But on LandRover sized vehicles there are instances such as climbing steep, firm but slippery slopes when you just have too much rubber on the road and the wheels just sit on top of the surface and spin uselessly instead of getting a decent bite. I had a system on my old 6x6 that enabled me to lift either rear axle off the ground to concentrate the weight on one axle for those instances, but that added extra complexity. The high degree of bogie articulation we have been discussing in this thread is also of the utmost importance if the extra axles aren't going to end up a liability offroad instead of an advantage. Climbing steep bank or hummocks is one example.If the suspension has inadequate articulation when the middle wheels reach the crest of the bank or hummock the rear axle and wheels will be off the ground. The weight of the axle/wheel assembly then becomes a counterweight to cause the vehicle the pivot on the middle axle and reduce weight and traction on the front axle. There is a video on You tube I think of a 6x6 converted LandRover 101 camper with non interconnected leaf spring suspension on both rear axles trying to climb over a fairly gentle sand dune that perfectly illustrates what I am referring to. Has anyone here seen it ? I can't seem to find it now for some reason. One other consideration is that if you are going to build a vehicle with an extra driven axle or two, it makes sense for the extra wheels to go some way to filling the gap between the front and rearmost wheels to reduce the chance of high centreing on hummocks, logs etc, and to give the vehicle at least some trench crossing ability. My vehicle on 9.00x16'' tyres with a wheelbase of 74''+39'' plus pto driven 4.00x9'' belly wheels and similar wheels on the front bumper could be persuaded to climb over a 3ft diameter log or cross a 4ft wide bottomless trench.

I'm getting too old and have too many committments to attempt to build another one with more reliable (non Rover) components but I would like to offer encouragement to anyone willing to have a go.

Bill.

Bill.

[NRS91]

hmm interesting...

im guessing that the diff input shaft wouldnt be able to take the forces of pivoting and driving the walking beam?

heres a bit more walking beam p0rn for ya http://www.amphibiousvehicle.net/amphi/L/t...al/twister.html

[Night Train]

Yes, adding axles is only effective if the axles are load and torque balancing to ensure that there is adequate and even contact with the ground for traction. Vehicle weight and floatation is also an issue hence mine only had 7.50x16 tyres and not 9.00x16 or bigger. Even then I was running at best part of 2.5 tons unladen. Traction with an extra ton plus in the back was really rather good!

The downside of having an extra axle is the effective overhang for loading. The balance point over the rear wheels moves from being the rear axle to being the pivot between the axles so some 20" further forward. Important if lift towing or loading right at the back of the load bed. Weight there effectively unloads the front axle.

I was looking for heavy and grippy for flat towing and pulling on and off road more then ultimate off road though I did also want it to be able to climb and articulate over rough ground too.

A Centaur half track would have been a nice alternative...

[NRS91]

i love the centaurs... bit expensive and rare for my wallet though...

any thoughts on my proposed swinging beam system?

[Night Train]

i love the centaurs... bit expensive and rare for my wallet though...

any thoughts on my proposed swinging beam system?

In theory the system would function but it would all depend on what parts were available and how they could be used.

I did look into using diffs to get crown wheels and pinions to make bevel boxes for just your description in the hope that they would be cheaper then getting specialist bevel boxes. The problem is that diffs and their innards don't lend themselves to this sort of conversion easily. Their overall bulk would make an axle very wide, effectively the width of 5 diffs with suspension mountings, brake housings, stub axles...

Just using the crown wheels and pinions would mean very accurate housings to be made up and also some fiddly shafting to fit the crown wheel without the need for the wide diff gear carrier and bearings.

I looked into industrial bevel drive gear boxes but they are very expensive to get new and very difficult to find just enough of the right ones second hand. Also industrial gearboxes tend not to be designed for the sort of shock loading at the wheel of an off roader. Any play induced breakage would be very costly.

The scale of fabrication involved probably be would be akin to building a pair of portal axles from scratch around a set of random diff gears, easier to just get one ready made and adapt.

However, if I was to make a walking beam axle I would do something like this:

The chain tensioning system would be like this: