LT230 PTO DIY kit possibly on its way

[lrfarmer]

keep you progress coming your idea is just the sort of thing i'd be after

[dirtydiesel]

In my humble opinion, the splines are more than strong enough!

It's the deep undercut behind the spline that i belive will fail, the material is under 3mm thick and being hardened both sides i think it will fracture under the shock loading you will be able to exert given that there is very little gearing to protect the drive from the winch.

If you compare it to a half shaft with tiddly little, shallow splines which in the case of uprated shafts will still hold at about 7000Nm when the shaft breaks - I think this amount of torque (500Nm) is trivial.

500nm would be a minimum, probably be less than most engines at idle through the first gear.

[CwazyWabbit]

Would the addition of some sort of cush drive be beneficial then?

[Bowie69]

Was thinking along similar lines.... Disco rear prop donut anyone?

[bill van snorkle]

It's the deep undercut behind the spline that i belive will fail, the material is under 3mm thick and being hardened both sides i think it will fracture under the shock loading you will be able to exert given that there is very little gearing to protect the drive from the winch.

500nm would be a minimum, probably be less than most engines at idle through the first gear.

You saved me along walk down to the shed to measure a gear.That is exactly my concern. I broke a similar ring of dog teeth on 2nd gear of a series 2 gearbox , the undercut of which i think is larger diameter than the LT 230 Pto spline undercut..

It might be ok as some suggest, but without the self locking feature of a low geared worm drive winch, I am not sure I'd feel too confident sitting in the vehicle while winching up some of the rock waterfalls we call 4wd tracks around here.

I'd be looking at the possibility fitting a larger diameter rear bearing to the rear bearing housing or new adaptor plate,machining up a heavy walled splined sleeve to press over the bearing journal and weld it to the larger more substantial bearing shoulder.If you cut series PTO dog teeth onto the sleeve there a choice of dog collars that can be adapted to the PTO output shaft. Old series 1st gears, front wheel drive dog clutches, low range slider gears, even PTO dog collars or complete PTOs for example.

Bill.

[bill van snorkle]

A couple of questions if I may?

Do some of the later gears continue the internal spline right through, past the PTO spline undercut ? That would significantly increase the cross sectional area of that section if they do.

Can someone please measure the internal diameter of a Salisbury carrier bearing for me? I don't have one to measure.

I'm looking at beefing up the PTO section of an LT230 to drive a 3rd axle via a second transfercase, and I'll never be convinced the standard PTO splined section is up to that task.

Bill.

[Soren Frimodt]

A piece of info that might interest you, is that the locking collar that engages the center diff, is bar a mm the same size as the output for the pto. It too does not have more than half the splines for easy engagement. And I've never heard of anyone stripping those, even though it effectively drives both axles.

[bill van snorkle]

A piece of info that might interest you, is that the locking collar that engages the center diff, is bar a mm the same size as the output for the pto. It too does not have more than half the splines for easy engagement. And I've never heard of anyone stripping those, even though it effectively drives both axles.

I don't have the pieces handy to verify that Soren, but I'd imagine the male splines(minor diameter of internally splined collar) would increase the cross sectional area of the collar.. What I do know is that I measured the wall thickness of the undercut section a series 2A 2nd gear that I broke the whole ring of teeth off and it measured 4mm thick verses 3mm for the LT230 PTO gear, and the series gear dog teeth ring is a larger diameter

Now 2nd gear only receives engine torque multiplied by what 2.5:1? My old 2 1/4 litre engine in those days wasn't particularly healthy, but lets say it was producing the full specified torque of 124 lb ft. Multiply that by 2.5 and it took around 310 lb ft of torque, shock loading from wheel spin when transitioning from wet white road marker paint to wet unpainted tarmac to break it.

Your PTO should be fine driving a sensibly geared winch, but IMO the Lt230 splines are not capable of delivering full engine torque multiplied by first gear ratio when driving a third axle cross country.

Bill.

[Soren Frimodt]

I see your concern Bill, but why do you not use a LT95 for your application instead then? Are they not source able in Aus? You could surely live without the 5th gear?

[Soren Frimodt]

On another note that undercut is really not very deep, you can only barely feel it with your fingernails. And there is no difference in length on those with full spline count and those without. I suppose the later type with the less splines is simply to save money as no one uses a PTO these days..

[simonr]

How about measuring the internal and external diameters inside the groove. If we make a guess at the material type we can make a stab at calculating the yield torque?

Si

[Troddenmasses]

If we make a guess at the material type we can make a stab at calculating the yield torque?

That's the difficult bit. The yield strength of possible materials is so incredibly different. At work (industrial instrumentation - properties of inorganic materials) we deal with gear teeth made of everything from grey cast iron, through lots of different grades of stainless, to titanium. The strength (and cost) between them differs hugely.

[bill van snorkle]

Soren, I have about 4 Lt95s in servicable condition, but the next 6x6 project should it go ahead is for someone else who already has a 200tdi 90..I personally prefer a pinion mounted drop box that I can quite easily make using series t/case parts.That would leave the PTO point available for a crawler box.

The undercut, deep or not still leaves a wall thickness of only 3.6mm. adequate for most PTO work, but not IMO enough to drive an axle with 36'' tyres..If the internal mainshaft spline went all the way through, the effective wall thickness would probably .have been enough. I'm working on a way where I can cut the PTO spline off the gear and sleeve up the bearing journal to 55mm diameter for a larger bearing. An old series front wheel drive output shaft can then be machined to press into the hole of the LT230 gear and welded in place. Then with an adaptor housing I can fit a standard series PTO,of which i have a few in the shed..

Bill.

Edit. Simon. The OD of the LT230 undercut is 40mm. The ID is 32.7mm.=3.65mm wall thickness

A series 2nd gear undercut OD is 47.75mm, the ID is 39.70mm approx.=4mm wall thickness

A series high range gear which simlarly will see full engine torque multiplied by 1st gear x 15% measurements are

OD 47.75mm, ID 34.7mm.= 7mm wall thickness.

[simonr]

That's the difficult bit. The yield strength of possible materials is so incredibly different. At work (industrial instrumentation - properties of inorganic materials) we deal with gear teeth made of everything from grey cast iron, through lots of different grades of stainless, to titanium. The strength (and cost) between them differs hugely.

I agree, however, if it's been hardened it would be reasonable to assume that it is made from a hardenable grade of steel. Also, it's likely to be forged or billet machined.

If you use the weakest hardenable grade likely and assume it's machined (also the weaker option) and calculate the yield strength for that. If This worst case turns out to be strong enough - then in all probability the real thing will be too.

Shock load magnitudes and fatigue life are difficult to estimate - but depending on the estimated strength even these may not be an issue.

I think this kind of worst case estimate holds value - particularly when you don't have the exact spec. It's proven very useful for me in the past - even just to rule things out.

Si

[bill van snorkle]

I agree, however, if it's been hardened it would be reasonable to assume that it is made from a hardenable grade of steel. Also, it's likely to be forged or billet machined.

If you use the weakest hardenable grade likely and assume it's machined (also the weaker option) and calculate the yield strength for that. If This worst case turns out to be strong enough - then in all probability the real thing will be too.

Shock load magnitudes and fatigue life are difficult to estimate - but depending on the estimated strength even these may not be an issue.

I think this kind of worst case estimate holds value - particularly when you don't have the exact spec. It's proven very useful for me in the past - even just to rule things out.

Si

Just ask Mr Ian nicely to put a gear in his halfshaft/cv joint destroying machine.

Bill

[Daan]

Have you compared it with the earlyer double tooth count version? It could be different. Not sure if the undrilled gear is still available new, but if it is, you could use it and smoke a hole in that? Also, it is worth checking what spline the underdrive is using in this area, that will get a lot of stick as well.

As mentioned, it is a bit pointless comparing different splines from different boxes, as material choice and heat treatment can make a huge difference. If anything, I say just run it and carry a spare gear.

Daan

[dirtyninety]

i say just let him build the bl**dy winch and stop picking faults!!

[dirtydiesel]

i say just let him build the bl**dy winch and stop picking faults!!

Wake up!!

I'm certainly not picking fault, just discussing the pro and cons.

Likley as not soren will have built the winch by now.

[FridgeFreezer]

Perhaps even more importantly, why is Dirtydiesel posting here instead of finishing my roll cage?

[bill van snorkle]

i say just let him build the bl**dy winch and stop picking faults!!

What a silly post!.I think the knitting forum is on another website.

Bill.

..

[simonr]

i say just let him build the bl**dy winch and stop picking faults!!

I don't think we're picking faults, instead, making the product as good as it can be.

If you are designing stuff commercially (can't think of anyone who does that ) these kinds of concerns are exactly what people will think and say when the product is launched - and thus is extremely valuable! Even if it's just having an answer to hand when a potential customer asks the question. I wish I'd had this kind of critical appraisal of some of X-Eng's products before they came to market.

I hope Soren agrees.

Si

[Soren Frimodt]

I Agree Simon, and the criticism that you get from doing an in-depth online description of your product as we have chosen to do here, will always seem a bit, shall we say violent. But I personally thought it would evolve far more, and silly posts with no real substance would fill the entire board. This however, is not the case, and for the most part I take this as healthy criticism.

Now, as I have stated earlier I am certain that the PTO spline of the gearbox will not be the weakest link. Other people might think otherwise, fair enough. But Bill's concern are not directly related to the product in-hand as he is planning to drive a separate axle through the PTO, which of course is a whole other game.

We are getting the splines cut as we speak and will have pricing some time next week. For now we are going to spend our weekend doing what we all really love, going mudding!

[simonr]

Another way to look at whether it's strong enough is to consider your prop shaft. Mine is 48mm outside diameter but only 2mm wall thickness - and has not broken yet. It is slightly different as in that groove, you will have two localised stress concentrations at either side of the root of the cut but without dimensional data it's impossible to say how much this will weaken it.

My gut feeling is the PTO output is strong enough for winching but a bit touch & go using it to drive an axle.

Si

[bill van snorkle]

Another way to look at whether it's strong enough is to consider your prop shaft. Mine is 48mm outside diameter but only 2mm wall thickness - and has not broken yet. It is slightly different as in that groove, you will have two localised stress concentrations at either side of the root of the cut but without dimensional data it's impossible to say how much this will weaken it.

My gut feeling is the PTO output is strong enough for winching but a bit touch & go using it to drive an axle.

Si

I agree and stated earlier that I think the spline will be strong enough for winching, but I'm not sure a long, 48mm dia 2mm thick ductile propshaft tube, which has the torsional cushioning protection of pneumatic tyres and flexible halfshafts could be compared with a short 40mm dia 3.6mm thick case hardened tube with a non radiused stress riser machined into it. driving rigid shafts into a rigid winch.

Having said that, i do now recall many many years ago, repeatedly breaking the axle gears of early Warn brand roller driven free wheeling hubs,where the designers stupidly offset the inner and outer splines of the gear with no overlap, that meant that full halfshaft torque was effectively going through a 30mm dia tube 2mm thick. Although I broke alot of them on 9.00x16 tyres,(I was getting them for peanuts) these had the reputation among many landRover owners of being a premium quality hub.

I would still be interested to know if the Esarco 8x8 had a strengthened pto gear to drive the additional 2 axles via the second transfercase.

Bill.

[simonr]

I agree and stated earlier that I think the spline will be strong enough for winching, but I'm not sure a long, 48mm dia 2mm thick ductile propshaft tube, which has the torsional cushioning protection of pneumatic tyres and flexible halfshafts could be compared with a short 40mm dia 3.6mm thick case hardened tube with a non radiused stress riser machined into it. driving rigid shafts into a rigid winch.

It is slightly different as in that groove, you will have two localised stress concentrations at either side of the root of the cut

I think we're probably on the same page?

I was just trying to come up with a real world example of something that works with similar (in this case higher) torque but has similar dimensions. Most people have trouble visualising magnitude of forces and strengths of materials - so a similar example serves to illustrate it.

I'll not pretend that I can run Finite Element Analysis in my head - but I can on the CAD and on the whole, the results have been backed up by experimental evidence.

I don't know why we are arguing over this - I think we are both saying pretty much the same thing and getting bogged down in the minutia of how accurate what for both of us is little more than a guess will be in reality.

Ultimately the best option is to try it. I think that at the very least, our 'guesses' give sufficient grounds for trying it out as the forces/strength is definitely in the right ball-park.

Si