QRTT...the Quick Release TurnTable

Hi all, when the "Big D" turntable came out they were a lot cheaper than the Cast turntables and you could easily change the wearing parts in the jaws and build up the front where the king pin pushed on and grind them out with a half worn out 4 inch grinder wheel. Also you did'nt have the bolt sticking out the front with them. - Kav

York.

...just to clarify my previous post, the "fixed" term applies to the whole semi trailer being not able to be separated...as in... always attached to each other, and with a degree of effort to part the prime mover from the trailer...

...if the whole outfit is always together, the slippage should be very much minimised which would hopefully mean a durable and reliable U bolted turntable hitch arrangement...

... afaik..way back in the day this set-up was all that was readily available, and i'm pretty sure the advent of the QRTT was probably seen as a bit of a luxury...with the problem of the U bolted base applied to the QRTT not overcome until the proper turntable angles, bolted to the chassis frame became the norm....

...just to clarify my previous post, the "fixed" term applies to the whole semi trailer being not able to be separated...as in... always attached to each other, and with a degree of effort to part the prime mover from the trailer...

...if the whole outfit is always together, the slippage should be very much minimised which would hopefully mean a durable and reliable U bolted turntable hitch arrangement...

... afaik..way back in the day this set-up was all that was readily available, and i'm pretty sure the advent of the QRTT was probably seen as a bit of a luxury...with the problem of the U bolted base applied to the QRTT not overcome until the proper turntable angles, bolted to the chassis frame became the norm....

The early QRRTT were fitted the same as the fixed type - as in using a timber insulater and 'U' bolts.

RE 'slipppage' if that means any forward or backward movement of the TT along the chassis - that was a big issue in accidents - like head ons or the likes. The TT would slide froward and crush the rear of the PM cab.

Progressive laws ware introduced - firstly a 'ramp' style affair had to be bolted to the chassis at the leading edge of the timber runner - then a 'strap' thingo was added - where it was welded to the TT frame and ran rearwards with a hook on the end that wrapped back under the chassis.

Then - the next change was similar to tipper mountings - where a couple of vetical straps were welded to the TT frame and bolted to the face of the chassis.

Next came the current design were the angle iorn strip was bolted to the outside to the chassis and the TT mounted to it.

When I get time I will post some example pics that show the above design progressions.

Oldfulla

thanks oldfulla for all that interesting info...

...the fixed style turntable i found must've been from way back in the day, as there's only the four U bolts holding the whole thing down to what was a Mk 1V Commer chassis...no other aids or restraints. I was amazed to find that the "box" section TT base was in fact heavy angle welded together to form the box...I'm pretty sure it's a Freighter TT and has the number A137 cast into the bronze bushed cup

...also the "slippage" referred to would be from the jolting (which i suspect would have occurred) from the bump and grind of the more regular parting of a truck and trailer that had the QRTT set-up...in other words the "bang" when you lock the pair in place...

...i guess the early fixed style TT also went hand in hand with the much shorter overall lengths, so the space the outfit took up was probably more manageable compared to what we see today....

Australia was very slow to adopt the logistics advantage of QRTT. In the USA and then Britain an operator would have more trailers than prime movers so that the prime mover was always on the road pulling a load while trailers were being loaded or otherwise held up.

mammoth I sought have always had the feeling that over in the US a lot of owner drivers were tow operators were as in Australia most owner drivers also there trailer dont no if this is true and I feel even Eruope was along the same lines as the US but I may have this all ass about

Paul

Hi Paul .. I'm pretty sure there wasn't a big, long time frame between the organising of proper interstate road transport (after Hughes and Vale 1954 ?) whereby the semi trailer really came to the fore in Australia.... and at least maybe not until 1962 with Cameron's bringing the Kenworths in, and O'Neils with the Peterbilts, did we see a big rise in the usage of the QRTT... ??

..I really haven't a clue here, but the theory seems reasonable....not forgetting that the biggest rigs we had after the war were mainly body trucks in the 'Territory pulling multiple trailers.....idstbc etc.

It always used to amaze me at the number of yard drivers that used to hook up without opening the jaws.The worst offenders that I saw was at Mayne's.Used to hear the shuttle drivers always complaining about all the slack in the pins !!! : : :

Paul, Europe was slow to adopt semi trailers as the most popular rig (well into the 70's) was a body truck and dog trailer.