Truck and pig into 19m

Wedgie, for a bit of logic to how much clearance you need between the truck and the trailer-
They are both near on 2.5M wide, so 1.25M being half of that will ensure that the 2 don't hit, I just round it up to 1300MM.

Thanks for the help guys. That's why the manager is set on a pig - for ease of loading all through the trailer by backing them together. Also ease of reversing for us farm boys (non-professional drivers...)

So I see how the 1300 is logical. Now I'm not trying to be smart, and you're clearly way more experienced than me. But surely that theoretical 1250 is only if the hitch as at the very back of the tray? Surely if you moved the hitch under the tray, as the drawbar length increased the more shallow the arc it creates so the closer the trailer can be without interference. In fact you made me have a more serious think about this and I did some theoretical (in a perfect world) calculations:

Maybe I'm missing something, but just drawing it out on an envelope say I want a 1m gap between truck and trailer, I'd need the hitch 280mm under the tray for the centre of the trailer to just kiss the corner of the truck. So his 560mm is well safe...

I don't know what tools you use in the industry for calculating this, but surely trailer builders have something to calculate along these lines using a mathematical model?

Also regarding front axle loading surely you can vary the load by altering rear overhang. I mean you could even make the rear overhang so large as to life the front axle up. So the cab over argument is less about front axle loading and more about rear overhang - with too much obviously still being very bad (or at least for us anyway - tried to take our Hino up to our top yards and it just sat on its overhang on the first woo boy)

Yes Wedge, longer drawbar allows trailer to be closer in the horizontal plane. Some 3 car carriers use this idea well.
Have to watch what happens vertically when travelling through dips, so you could run close up on highway. Should be possible to close up to 500mm. On bad roads or off road open out to 1300mm as others suggest. Unlikely officers with tapes would spend too much time around a stock crate.
Dog trailers reasonable for sheep but less suited to cattle, especially with short drawbar, as little sway magnifies along the rig. Best position of hitch for least sway is just behind rear diff at axle height. Not always practical but the closer the better result.
First outfit I saw was built from back end of a widespread semi. The stock traveled well as axle placement reduced roll and sway on rural roads. Others were made with triaxle setups which steered easier than the spreads.
Great to see research done before buying! Cheers, Paul

G'day Paul nice to her about other set ups. So do others run different draw bar lengths depending on road types? Just not sure how practical it is having two towing lengths. I like the idea as it's a good way round but I can see someone having it long off road then forgetting to retract on the road. Although I could rig up a flashing warning light in the cab to remind you you're in "illegal mode"! Although as it seems having the hitch as close as possible to the diff means a longer drawbar so it can have enough clearance legally for all situations anyway. Either way I think it's enough info to put it to the manager that a bonnet gets our combined tray length and is the go . I'm sure the body builder (probably obeico) will have an opinion too

Yeah have been trying to work out how to find the worst case scenario dip and consequent reduction in gap caused by it on our regular between property run. Chances of being pulled up on that route as close to 0 as you can get - never seen a cop on it in 3 years let alone RTA. But we like to be legal...

Wedgy
Gudday M8

time to grab sum A4 size cardboard or Cornflake box
mark n cut out n place drawbar @ different places along
center line n measure the clearance @ different arcs
a good scale is 250mm = 2500mm (2.5m)



cya

love it swishy good one will try it. Always good to back up calculations with some practical meaurements!

Draw Bar 2 Close



LOL

cya

Wedgie, Here's a Truck with the same driveline as the Star/KW-T358.
& according to the Brochure,
Will build a long Wheelbase one Ex factory.

www.macktrucks.com.au/trucks/metro-liner/

Swishy's right Wedge, lot can be done in the shed with cardboard, old school rulers, tin lids, wire and nails. Helps my old grey cells. Operator's let the drawbars out to enter farms for sharp turns into gates, over culverts, creek crossings etc. Is that track across from north of Coolah, over the rail line east to Bundella still used? Could just get up out of the creek crossing going in with cattle on semi's in 1966. Turning right whilst climbing the crates were close to hitting the cab. That T409 would need 7200 wheelbase for 8500 (28') tray. Gives centre of load (Tray, Crate & Payload) 1100 in front of centre of drive group. Say that totals 16 tonne, throws 2.4 on the steer and 13.6 on the drive. Overhang 3150 (10'4") & total truck length about 11750, bit over 38'6". Pig is to be 6100 (20') leaves 1150 gap in between. Theoretical only, as might need a bit more space between cab and crate as well as other practical considerations. The other advantage you have is being able to load stock light in the front pen and heavier in the back pen(s) to shift weight back off the steer. To position a load on a truck or trailer,
L = total load. ( say 16 tonnes )
W = wheelbase ( say 7200 )
F = front axle group capacity, allowable subtract tare ( say 2.5 tonnes )
D = centre of rear axle group to centre of load

Calculate D = W x F / L D = 7200 x 2.5 / 16 D = 1125 Hope this is helpful, cheers from Paul.

this is 1 for debo he runs a truck n pig with stockcrates in south Gippsland