QRTT...the Quick Release TurnTable

I reckon the QRTT was probably invented about 1920/21 because GMC were supplying Detroit Trailer Co trailers with their prime movers at that time with quick release. My 1923 has quick release, with pin on the chassis mounted plate. Also has a direct coupling to the landing legs, wind the legs up and the pin latch closes....I know some blokes who could use that today. It was probably one of the first QRTT's in Aust.

As a kid with the grease gun in the 50's and 60's most trucks had either a QRTT or some old fashioned greasy plate design.
Our STECO trailers had their own semi quick hitch design turntable, couple of big bolts and clamps around the cross pivot which was about 2.5" bar. Actual turntable was oil bath.
But it didn't really matter as nobody had landing legs, saving on tare weight perhaps?
We used a couple of 44's when removing the trailer during the slack season while the trucks sat in the back yard for a few months.
Looking at the stuff on today's roads, haven't seen a primer mover without a quick hitch, same for the various combinations.
Only fixed ball race jobs I see are single dolly dogs. Once the dolly moves to multiple axles she's got a quick hitch too.
Obviously the pin has got a LOT bigger since those early days.

I feel I remember seeing Mcgrath adds when looking thru some old truck and bus magazines for somebody that was righting a book on here ??????
The Mcgrath add was late 60's and the quick release was an option not standard but I may be wrong there as well

Paul

I have an example of the "oil bath" turntable which was an early version of ball race turntable. To disconnect the trailer you had to get under with spanners and jack the trailer off.
"greasy plate' has two meanings, one being used nowadays to describe a QRTT with fixed fifth wheel on prime mover, and the other being the now out of fashion 'stabilised turntable' in which the fifth wheel rotated on a plate around a bronze bush of about 10" diameter.

....g'day all .. I found a very old fixed style turntable recently, and was wondering what's the legal situation these days regarding the usage of timbers and U bolts holding the whole thing down?....

....the way the historic movement is headed regarding self regulation and duty of care, it crossed my mind that they may be OK if done correctly...considering they were legal once...??

Timber would have to have an Adr

Fixing a turntable with u bolts is a strict no no on full rego but there are plenty of examples on historic rego. Trouble is, if a trailer goes awol due to u bolts letting go the insurer may not come to the party to pay for resulting carnage. This may be one of the issues behind the limited load capacity allowed on historic rego (less in some states than others).

Correct Mammoth, yet who can say they've ever seen a rig with "U" bolted turntable come to grief solely due to that system.
I've seen roll overs with the PM suspended by the turntable and she's all stayed together, but of course they were not the huge GCW of a modern setup.
Their main fault was the frame would slip on the chassis when backing under, infinite loads on the "U" bolts in that situation.
So as a half measure, the frame scored some shear bolts to the chassis around it's centre point and still retained the "U" bolts. No more slipping.
One has to remember these older trucks had flimsy chassis' which didn't like the point load of a turntable, so the frames were made quite long in an effort to distribute the load over a greater chassis length.
Our Commers had 6-sets of "U" bolts and would still crack the chassis exactly where the frame ended.
The Beavers with much stronger chassis just had the normal plate with 4-shear bolts into the side of the chassis rails and then 4- "U" bolts.

...great info fellas .. Jeffo, I imagine potential for slippage would be greatly reduced if the U bolted turntable was fixed to the trailer with the two greasy plate and big centre bolt...in other words, a non QRTT set-up...

...i guess they were a pain, but did you run these much earlier style of hitch?...

The slipping I was referring to was between the turntable frame and the truck chassis.
The frame usually had timber strips as an insulator and when backing under the trailer and pushing to lock, the whole frame would try to slide along the truck chassis.
Didn't matter how tight you did up the "U" bolts, you could always get a bit of movement until the "U" bolts cocked at a bit of an angle and then things locked hard.
By welding a piece of flat bar with a couple of bolts in shear from frame to chassis, no more movement.
Of course the next stage was fully bolted and to forget the "U" bolts.
Some trucks like Merc. with very light chassis rails complimented with flitch plates, doublers etc didn't lend themselves to "U" bolting at all.