I recall that in the late 60’s and early 70’s the Milnthorpe firm of Davy& Co subsiduaries K.Fell & J.L.Ion operated trailing axle AEC Marshals which were basically Mercurys with a third axle.These 6 wheelers were mainly operated on Contract to the Libby factory next door to them.From memory they had light weight wood ali 27ft flats and could carry 15ton payload at 22ton GVW.So they were more-or-less the equivalent of an eight wheeler.Cheers Bewick.
A bit like the artics, Dennis- gross weights for 4-axled artics were 24 tons at the time: if you put a Mercury unit on the front instead of a Mandator, you gained about a ton of payload.
Retired Old ■■■■:
A bit like the artics, Dennis- gross weights for 4-axled artics were 24 tons at the time: if you put a Mercury unit on the front instead of a Mandator, you gained about a ton of payload.
Those were the days ROF,when the Four-in-line trailer could operate at 24 tons GVW with a light weight unit like a Comet or Dodge 308 the only 32 tonners were an 8 wheeler and trailer.Cheers Dennis.
We had NLG 443H a TGM Mercury artic that had a Pitt Tandem 4 lightweight 30’ trailer behind it. With a GVW of 26 tons it tared off at exactly 7 tons giving 19 tons payload, not much behind a Mandator. I once loaded 2 Caterpillar bulldozers down in Surrey to fetch back up to Manchester, the trailer was like a bannana, but not a murmer of protest from the Mercury. I do recall the trailer tyres got a bit warm though. 
Can you explain the axle weights to get 24t all up?
In that era in Aus, we would have had 14t on the close bogie trailer group, 8t on the single drive and 4t on the steer giving a total of 26t.
A big wide spread would go out to 16t on its axle group.
Tandem drive group would be 16t and I think a lazy or pusher axle (undriven) was 7t.
A simple question but a complex answer.
From 1958 to 1965 in the UK, the maximum GVW / axle loading weights in each vehicle category were (ignoring the intermediate weights): -
2 axle rigid 14 tons, 5 tons front axle 9 tons rear axle
3 axle rigid 20 tons, 5 tons front axle 15 tons rear bogie
4 axle rigid 24 tons, 4 tons each front axle 16 tons rear bogie
4 axle rigid plus 2 axle drawbar trailer 32 tons (24 tons gvw prime mover 8 tons gvw trailer)
4 axle artic 24 tons (a four-in-line semi-trailer was classed as a two axle semi-trailer)
From 1965 maximum gross vehicle weights were increased:-
2 axle rigid 16 tons, 6 tons front axle 10 tons rear axle
3 axle rigid 22 tons, 6 tons front axle 16 tons rear bogie
4 axle rigid 24, 26, or 28 tons depending on outer axle spread. (28 tons eight wheelers were very rare in the UK because they were so unwieldy)
4 axle artic, 30 / 32 tons. (32 tons required outer axle spread limitations to be met within overall combination length limits and the trailer bogie was at the extrmity of the trailer) 5 tons front axle, 10 tons drive axle, up to 17 tons on the trailer bogie.
5 axle artic 32 tons.
Thanks for the explanation.
What I’d presumed as the odd keystroke error was interpretation of those amazing regulations.
I thought we had it tough with minor differences between the various States.
You have some big axle loads, especially the 2-axle rigid.
Also clears up a question I’d had why did they offer a heavy tare truck like a Beaver as a 2-axle rigid.
Truck’s heavy tare plus the tray would be useless in 60’s Aus with a max permitted of 12t., it might legally carry a load of 4 to 5t.
Between 1968 and 1971 there were some minor amendments that tidied things up a bit.
For example artic trailer lengths were increased from approx. 33 ft to 40 ft and this permitted 32 tons gvw on a 4 axle artic. It meant the end of the 5 axle artic for a few years until later gross weight increases.
A rigid six-wheeler gvw increased from 22 to 24 tons (basically 2 tons extra payload which helped the tipper men) and the rigid eight-wheeler gained the most increasing to 30 tons gross on a manageable wheelbase and outer axle spread.
I have a feeling that BTC (British Trailer Company) used to run advertisements in commercial Motor and the FTA year books which claimed that the axle weight for a four- in- line trailer on suitable tyres was 11 tons.
cav551:
I have a feeling that BTC (British Trailer Company) used to run advertisements in commercial Motor and the FTA year books which claimed that the axle weight for a four- in- line trailer on suitable tyres was 11 tons.
Your quite right the 4-in-line axle was rated at 11tons and BTC were the main manufactures at time although other trailer builders such as York built four-in-lines.I knew the former Sales Director of BTC,Jim Walmsley aka “Pugwash” a long time afterwards BTC had finished and he was running Municipal Trailers of Bamber Bridge.Cheers Bewick.
gingerfold:
A simple question but a complex answer.From 1958 to 1965 in the UK, the maximum GVW / axle loading weights in each vehicle category were (ignoring the intermediate weights): -
2 axle rigid 14 tons, 5 tons front axle 9 tons rear axle
3 axle rigid 20 tons, 5 tons front axle 15 tons rear bogie
4 axle rigid 24 tons, 4 tons each front axle 16 tons rear bogie
4 axle rigid plus 2 axle drawbar trailer 32 tons (24 tons gvw prime mover 8 tons gvw trailer)
4 axle artic 24 tons (a four-in-line semi-trailer was classed as a two axle semi-trailer)From 1965 maximum gross vehicle weights were increased:-
2 axle rigid 16 tons, 6 tons front axle 10 tons rear axle
3 axle rigid 22 tons, 6 tons front axle 16 tons rear bogie
4 axle rigid 24, 26, or 28 tons depending on outer axle spread. (28 tons eight wheelers were very rare in the UK because they were so unwieldy)
4 axle artic, 30 / 32 tons. (32 tons required outer axle spread limitations to be met within overall combination length limits and the trailer bogie was at the extrmity of the trailer) 5 tons front axle, 10 tons drive axle, up to 17 tons on the trailer bogie.
5 axle artic 32 tons.
I think the 3 axle “steer” was rated at 18tons so would that have been 9ton rear axle and 2x4:5 ton steer axles ? Cheers Bewick.
With regard to the 4-in-line configuration, I think I remember that the wheel centres had to be 18 inches apart to qualify for the maximum weight.
Retired Old ■■■■:
With regard to the 4-in-line configuration, I think I remember that the wheel centres had to be 18 inches apart to qualify for the maximum weight.
Aye & They were a tyre fitters delight Eh, Ha Ha, Regards Larry.
Just found my York trailers Service manual for May 1975. The York 4 in line , officially a “twin oscillating axle”, was called a Transfour suspension by York. It advises to set up the axle alignment offset by 1/16" to help the axle climb out of the road camber to prevent crabbing. There were two totally different versions.
Bewick:
gingerfold:
A simple question but a complex answer.From 1958 to 1965 in the UK, the maximum GVW / axle loading weights in each vehicle category were (ignoring the intermediate weights): -
2 axle rigid 14 tons, 5 tons front axle 9 tons rear axle
3 axle rigid 20 tons, 5 tons front axle 15 tons rear bogie
4 axle rigid 24 tons, 4 tons each front axle 16 tons rear bogie
4 axle rigid plus 2 axle drawbar trailer 32 tons (24 tons gvw prime mover 8 tons gvw trailer)
4 axle artic 24 tons (a four-in-line semi-trailer was classed as a two axle semi-trailer)From 1965 maximum gross vehicle weights were increased:-
2 axle rigid 16 tons, 6 tons front axle 10 tons rear axle
3 axle rigid 22 tons, 6 tons front axle 16 tons rear bogie
4 axle rigid 24, 26, or 28 tons depending on outer axle spread. (28 tons eight wheelers were very rare in the UK because they were so unwieldy)
4 axle artic, 30 / 32 tons. (32 tons required outer axle spread limitations to be met within overall combination length limits and the trailer bogie was at the extrmity of the trailer) 5 tons front axle, 10 tons drive axle, up to 17 tons on the trailer bogie.
5 axle artic 32 tons.I think the 3 axle “steer” was rated at 18tons so would that have been 9ton rear axle and 2x4:5 ton steer axles ? Cheers Bewick.
Yes, correct. Although the AEC Mammoth Minor tractive unit had its two steer axles rated at 4 tons each for 32 tons gvw.
Bewick:
cav551:
I have a feeling that BTC (British Trailer Company) used to run advertisements in commercial Motor and the FTA year books which claimed that the axle weight for a four- in- line trailer on suitable tyres was 11 tons.Your quite right the 4-in-line axle was rated at 11tons and BTC were the main manufactures at time although other trailer builders such as York built four-in-lines.I knew the former Sales Director of BTC,Jim Walmsley aka “Pugwash” a long time afterwards BTC had finished and he was running Municipal Trailers of Bamber Bridge.Cheers Bewick.
We had a Boden four-in-line that was made after 1965, it was 30’ long IRC, but it might have been 33’. It was a good trailer and was usually behind HUB 311E, a TGM Mercury that was plated for 25 tons GVW, and it was another first class AEC that gave sterling service. It was one of the smoothest lorries I’ve ever driven when setting off fully freighted.
Lawrence Dunbar:
Retired Old ■■■■:
With regard to the 4-in-line configuration, I think I remember that the wheel centres had to be 18 inches apart to qualify for the maximum weight.Aye & They were a tyre fitters delight Eh, Ha Ha, Regards Larry.
And a driver’s nightmare Larry in the days when we carried a spare and all the wheel changing tackle to do them ourselves. Not so fond memories of changing an inner on a 4-in-line outside Wetherby Racecourse on the A1 loaded with brown reels of paper from ELPM at Radcliffe for Hugh Stevenson at Darlington. 
Glad that 4-in line idea didn’t head down here, the only side by side arrangements we have are rows of 8 etc on floats.
Was there a sound reason to go for such an arrangement?
Most axle load restrictions can be traced to some road engineering feature.
The most common design criterion here was bridge beam spacing at a nominal 8’-0", hence the 8’1" wide spread which (hopefully) only ever had one axle per bridge beam.
A close bogey had 14t for the group and as the axle spacing increased, the allowable axle load also increased.
We went to 9’1" (16t) and later versions went way further until the whole concept was binned and tri-axle (22t+) became the standard.
cargo:
Glad that 4-in line idea didn’t head down here, the only side by side arrangements we have are rows of 8 etc on floats.
Was there a sound reason to go for such an arrangement? Most axle load restrictions can be traced to some road engineering feature.
The most common design criterion here was bridge beam spacing at a nominal 8’-0", hence the 8’1" wide spread which (hopefully) only ever had one axle per bridge beam.
A close bogey had 14t for the group and as the axle spacing increased, the allowable axle load also increased.
We went to 9’1" (16t) and later versions went way further until the whole concept was binned and tri-axle (22t+) became the standard.
Probably it was a result of several designs that came about to combine a lightweight answer to the restrictive Construction and Use Regs and gross weight limits. I think that the idea could have originated with Scammell in the 1920s.
Some accounts say the layout spread the weight more evenly over the four wheels and tyre life was extended as debris did not damage tyre walls as much as it did with twin wheels when for instance stone or bricks jammed between the wheels when on sites, not sure this claim is valid though as they still got punctures no more or less than twins. The advantage was an extra Ton was gained on the axle weight, I suppose they filled a gap in the market at the time and plenty of companies ran them. Back to the Mercury though I thought they did look a nice balanced outfit when coupled to the 28ft Single axle type with the axle positioned at the extreme rear of the trailer or with the very short Dumper types.