Weak bolts

[BrendAn]

Off on another tangent now.

Why when I read aircraft specs is neg g is always lower than positive g in the airframe stress limits. 

Probably a dumb question but I don't know the answer.

 

[Old Koreelah]

Trucks in Australia are different to what you see elsewhere.

 

Never saw a bullbar in Canada, but lots of triple-axle drives- presumably for icy roads.

 

In southern England I’ve seen lots of single-axle drives, with a second axle of single wheels sometimes sharing the weight, sometimes retracted.

 

In London a few prime movers with such short wheelbase the axle just in front of the drive axle has steerable wheels.

 

 

[turboplanner]

5 hours ago, Old Koreelah said:

In southern England I’ve seen lots of single-axle drives, with a second axle of single wheels sometimes sharing the weight, sometimes retracted.

Single Drives are the most fuel efficient and lowest cost, but we've limited their capacity because of our old country bridges, and historically we solved that by spreading axles and adding more of them to carry more payload on longer trailers, so it's not unusual to see tri axle Prime Movers, and four drive axle units are just starting to appear.

Axle lift introduces an extra maintanance cost and historically they've come in, then to maintenance has been too expensive and they've disappeared for a few years.

 

Sometimes though the mind boggles:  https://www.facebook.com/watch/?v=1076006343295531

 

Short wheelbase Prime Movers were common in Australia in the 1960s, and often had pusher axles (in front of drive axles). There were also a lot of Twin Steer single Drives and Twin Steer Tandem Drives, but the combined extra costs of tyre scrub, fuel consumption and maintenance saw the volume drop to a trickle.

 

The short WB hasn't come back, but Twin Steer has, and steerable rear axles have.

 

Australia used to follow Europe when Leyland, ERF, AEC, Atkinson, Foden were around but the EU regulations have caused us to drift apart. Top photo is the cutting edge fuel delivery combination in Sweden and Denmark this year.

On the right an Australian 19 Metre B Double. The short wheelbase of the Australia truck allows a much better turning circle and much easier reversing and if someone wants diesel in a hurry it can drop its petrol trailers and take a prefilled load out from the depot. EU is limited to one trailer.

Edited October 2, 2022 by turboplanner

[BrendAn]

10 hours ago, BrendAn said:

 

I would consider a day cab Kenworth a short wheelbase and they are popular pulling tankers. I drove a new t408 short wheelbase pulling a 25 mt double from Maffra to Bega for a few years.  And I drove a standard wheelbase k125 twin steer tipper with 2  tri dollies and 2 tri grain trailers, 121.5 ton gross and never noticed any abnormal tyre wear.  Certainly noticed it on tri drive prime movers though.  My man rigid is single drive with a lazy axle. Awful setup.

Edited October 2, 2022 by BrendAn

[turboplanner]

2 hours ago, BrendAn said:

I would consider a day cab Kenworth a short wheelbase and they are popular pulling tankers. I drove a new t408 short wheelbase pulling a 25 mt double from Maffra to Bega for a few years.  And I drove a standard wheelbase k125 twin steer tipper with 2  tri dollies and 2 tri grain trailers, 121.5 ton gross and never noticed any abnormal tyre wear.  Certainly noticed it on tri drive prime movers though.  My man rigid is single drive with a lazy axle. Awful setup.

This is short wheelbase, and these are on 9.00 x 20 x 12 ply, they'd look shorter still on 11Rs

[Bruce Tuncks]

My in-laws were talked into a 4 wheel van, with a wheel on each corner. It was road-trains that convinced them it could be done.

Well it towed terribly. It swayed so badly that you had to go really slowly, like 50kph.

I have seen road trains where the last trailer was kicking dust from each side of the road, alternately, as it sped up the stuart highway.

I do know it can be done to make them behave, it must be black magic.

[BrendAn]

1 hour ago, turboplanner said:

This is short wheelbase, and these are on 9.00 x 20 x 12 ply, they'd look shorter still on 11Rs

That is short. Before my day. Probably Gardner powered are they.

[turboplanner]

50 minutes ago, Bruce Tuncks said:

My in-laws were talked into a 4 wheel van, with a wheel on each corner. It was road-trains that convinced them it could be done.

Well it towed terribly. It swayed so badly that you had to go really slowly, like 50kph.

I have seen road trains where the last trailer was kicking dust from each side of the road, alternately, as it sped up the stuart highway.

I do know it can be done to make them behave, it must be black magic.

Vehicle dynamics are complicated; a lot of copies fail. It would be possible to build that van configuration, but tyre specification, track, suspension, wheelbase, anti roll control, turntable setback, draw bar length all play a part in the harmonics, and with that size trailer you're working with ground zero, rather than making a 10% improvement on your last design. On top of that the drawbar would be connected to a towball swaying in the breeze a looong way behind the rear axle which is designed for soft, smooth ride - the perfect storm.

[turboplanner]

1 minute ago, BrendAn said:

That is short. Before my day. Probably Gardner powered are they.

The Gardner was the longest living, but 52 mph flat out.

Best sounding was the Rolls Royce.

Best performing were Detroit 6V71, 8V71 replaced by the 92s then Cummins as the emissions started to bite.

Angel gear was used to shorten trip time.

A TNT subbie, Jimmie Dugan had a 6x4 and let it go on the first or second Moonbi. "I realised too late that there was another hill" he said "and she kept on picking up speed. The rear end was jumping and chattering at 100 mph, and then she went all quiet. I thought I'd gone to heaven, but then she slowed down and I was OK"

[onetrack]

I travel the Great Northern Hwy, North out Perth fairly regularly, and this highway is overpopulated with triple and double roadtrains as well as huge number of low-loaders. The roadtrains nearly outnumber the cars. Most of the rigs are well behaved, but I've come up behind several where the back trailer was swaying and swerving to a serious and concerning level - and all these badly behaving end trailers were on airbag suspension.

I don't know how the airbag suspension is set up, but I suspect the airbag valving arrangement is developing a fault, or something else in the suspension that is supposed to dampen roll is not working correctly, or is worn. I haven't seen a spring suspension end trailer, misbehave like an airbag-sprung suspension does, on an end trailer,

[turboplanner]

43 minutes ago, onetrack said:

I travel the Great Northern Hwy, North out Perth fairly regularly, and this highway is overpopulated with triple and double roadtrains as well as huge number of low-loaders. The roadtrains nearly outnumber the cars. Most of the rigs are well behaved, but I've come up behind several where the back trailer was swaying and swerving to a serious and concerning level - and all these badly behaving end trailers were on airbag suspension.

I don't know how the airbag suspension is set up, but I suspect the airbag valving arrangement is developing a fault, or something else in the suspension that is supposed to dampen roll is not working correctly, or is worn. I haven't seen a spring suspension end trailer, misbehave like an airbag-sprung suspension does, on an end trailer,

It's not the suspension which is the same as with Semi trailers and B Doubles which are direct connected to either the truck fift wheel, or the fifth wheel on the trailer ahead, and whera that movement doesn't occur.

 

If you want the precise cause, it's the Overall Length legal limit, which is also the cause of inadequate sleeper length and wrong cab type, all in the name of a political reassurance to appease "motorists" who apparently complain about the enomous trucks.

 

Where a converter dolly is used, the length issue means a drawbar length about half what it should be, and it's the self steering whip I described earlier. the whip travels back and is magnified by each converter dolly. On the Atherton Tableland main north south highway I followed one which was flicking from the dirt on the left side to the dirt on the opposite side of the road. In the last 30 years the Queensland roads have been widened on most of the main route. If you call them up on the CB they'll slow down and its easy to get a caravan past them.

 

[onetrack]

I knew about the short dolly drawbar problem back in the early 1970's, from the Goldfields of W.A., where triples and even quads were being used back then.

Can you recall the Transtars that Great Boulder Mines used in that era? The Transtars pulled 4 trailers with 100 tons payload into Kalgoorlie from out East, and that was mind-boggling at the time.

Unfortunately the Transtars weren't up to the work, and there was a pile of buggered Eaton diffs in the workshops, that you couldn't jump over!

On top of that, the Transtar cabs fell to pieces on the horrendous road East of Kalgoorlie, good roads were few and far between back then. Even the drivers seats broke away from their mountings!

But the experiences of Great Boulder, Gascoyne Trading, and other contractors around Kalgoorlie at that time, soon saw short drawbars lengthened, to provide much more stable roadtraining.

[turboplanner]

1 hour ago, onetrack said:

I knew about the short dolly drawbar problem back in the early 1970's, from the Goldfields of W.A., where triples and even quads were being used back then.

Can you recall the Transtars that Great Boulder Mines used in that era? The Transtars pulled 4 trailers with 100 tons payload into Kalgoorlie from out East, and that was mind-boggling at the time.

Unfortunately the Transtars weren't up to the work, and there was a pile of buggered Eaton diffs in the workshops, that you couldn't jump over!

On top of that, the Transtar cabs fell to pieces on the horrendous road East of Kalgoorlie, good roads were few and far between back then. Even the drivers seats broke away from their mountings!

But the experiences of Great Boulder, Gascoyne Trading, and other contractors around Kalgoorlie at that time, soon saw short drawbars lengthened, to provide much more stable roadtraining.

In my opinion, WA had the best road regulations of all the States. I could set up a B Double on Conventional Cab with a 56 inch sleeper and still be withing overall length. The Eastern States have splintered into a million pieces with PBS.

 

Gascoyne Trading were one of the best Pioneers in Road trains.

 

I specced a few, and at the time you had a foolscap pad and a calculator and had to do all the calculations. You'd start off with, say, a 300 bhp SAE Gross engine and take off 25 hp for the air comressors, 15 for air conditioning, 20 for alternators etc until you got to nett, rear suspension was usually AC6S Six Rod which maximised traction, Rockwell SSHD axles (well above Easton No3s),double channel chassis. You'd be up to three pages with the add ons. Often the Prime Mover was actually a twin steer tandem drive rigid which kept to a straight line better and it carried freight and towed the first trailer. Once you'd added up the weight of all the extra comonponents and with the Nett hp you could calculate startability, gradeability, 1% grade speed (you needed to be able to hold cruise speed on that grade). Everything had braces and gussets and extra bolting, and they did the job well.

 

Other people copied them; I hadn't heard about the Transtars. The Transtar was a great truck in the western US; Arizona, Nevada, California and it was released in Australia. It actually worked very well on Brisbane to Darwin, but I think in the west you'd wonder what all the people involved including the customers were thinking.

[spacesailor]

It,s not just the length that is problematic .

A three trailer tried to get over the Hawksbury river By ferry. 

BUT

due to its 100 k or ton load per trailer the poor ferry coudn,t keep its nose Above water.

AND the hapless  driver couldn,t reverse off the ferry , ( prime mover & one trailer ).

spacesailor

 

[BrendAn]

6 hours ago, turboplanner said:

The Gardner was the longest living, but 52 mph flat out.

Best sounding was the Rolls Royce.

Best performing were Detroit 6V71, 8V71 replaced by the 92s then Cummins as the emissions started to bite.

Angel gear was used to shorten trip time.

A TNT subbie, Jimmie Dugan had a 6x4 and let it go on the first or second Moonbi. "I realised too late that there was another hill" he said "and she kept on picking up speed. The rear end was jumping and chattering at 100 mph, and then she went all quiet. I thought I'd gone to heaven, but then she slowed down and I was OK"

Great post.  I remember going to Sydney with one of my uncle's when I was a kid. Cabover 871t. Hitting 95 mph down the hills around Cooma.  He only lived till he was 34 . Blew a steerer down a hill near nimatebel.

[BrendAn]

1 hour ago, spacesailor said:

It,s not just the length that is problematic .

A three trailer tried to get over the Hawksbury river By ferry. 

BUT

due to its 100 k or ton load per trailer the poor ferry coudn,t keep its nose Above water.

AND the hapless  driver couldn,t reverse off the ferry , ( prime mover & one trailer ).

spacesailor

 

Why would there be a 100 ton roadtrain near the Hawkesbury. 

[BrendAn]

2 hours ago, turboplanner said:

In my opinion, WA had the best road regulations of all the States. I could set up a B Double on Conventional Cab with a 56 inch sleeper and still be withing overall length. The Eastern States have splintered into a million pieces with PBS.

 

Gascoyne Trading were one of the best Pioneers in Road trains.

 

I specced a few, and at the time you had a foolscap pad and a calculator and had to do all the calculations. You'd start off with, say, a 300 bhp SAE Gross engine and take off 25 hp for the air comressors, 15 for air conditioning, 20 for alternators etc until you got to nett, rear suspension was usually AC6S Six Rod which maximised traction, Rockwell SSHD axles (well above Easton No3s),double channel chassis. You'd be up to three pages with the add ons. Often the Prime Mover was actually a twin steer tandem drive rigid which kept to a straight line better and it carried freight and towed the first trailer. Once you'd added up the weight of all the extra comonponents and with the Nett hp you could calculate startability, gradeability, 1% grade speed (you needed to be able to hold cruise speed on that grade). Everything had braces and gussets and extra bolting, and they did the job well.

 

Other people copied them; I hadn't heard about the Transtars. The Transtar was a great truck in the western US; Arizona, Nevada, California and it was released in Australia. It actually worked very well on Brisbane to Darwin, but I think in the west you'd wonder what all the people involved including the customers were thinking.

I can't talk about fancy calculations and design stuff. But I can tell you the order of stability in different combos I have driven.  C501 with triples on bogie dollies the worst. Next was the eight wheeler and 2 trailers. Then an S2 pulling doubles with a single point dolly.  T 650 with c train. Was very stable,that's 2 semis with an a trailer in the middle. 

Sar with 2 semis then a b double at the back. A trailers really stabilise things. The trouble with quads is the slightest turn of the wheel results in a lot of movement at the rear. 

[BrendAn]

And Kenworth make the only truck suitable for outback work. Nothing else comes close.

[turboplanner]

10 minutes ago, BrendAn said:

And Kenworth make the only truck suitable for outback work. Nothing else comes close.

Propaganda.

Depends who is engineering the truck. Kenworth can do that and do.

Several others can and do

[BrendAn]

21 minutes ago, turboplanner said:

Propaganda.

Depends who is engineering the truck. Kenworth can do that and do.

Several others can and do

You haven't spent much time in the bush then.  Nothing else comes close.  Euro trucks fall to bits . Mack's are not too bad. Scania make a heavy prime mover which is ok on mine sites. All the bits that fall off are contained on site😀.  Honestly turbo ,you know I am right.   I understand you want to make me look like a dickhead but I do that on my own .😁

[facthunter]

THIS should at least be in off topic. It's getting a little UNTIDY under "weak bolts"  Nev.

[onetrack]

I don't know about the Eastern States, but out of all the makes hauling roadtrains around W.A., you'll see 2 Kenworths for every other make of truck. Volvo probably comes in 2nd - and Mack, which used to be the leader of the heavy-duty trucking makes, is a very distant number today, ever since they climbed into bed with European manufacturers.

[facthunter]

C'mon enough of the Truck talk. It's like a Pi$$!ng contest. This forum is about aeroplanes. Nev

[BrendAn]

4 minutes ago, onetrack said:

I don't know about the Eastern States, but out of all the makes hauling roadtrains around W.A., you'll see 2 Kenworths for every other make of truck. Volvo probably comes in 2nd - and Mack, which used to be the leader of the heavy-duty trucking makes, is a very distant number today, ever since they climbed into bed with European manufacturers.

All the roadtrains I mentioned were in w.a.. we lived in Albany. Worked from Port Hedland to Albany over the years.  Better close this thread before nev blows a valve. 

[BrendAn]

3 minutes ago, facthunter said:

C'mon enough of the Truck talk. It's like a Pi$$!ng contest. This forum is about aeroplanes. Nev

How do I move it . Or can I change the name of this thread.