Thread: Another bloke needing advice - drawbar mount?

Hi guys, managed to find this pool of knowledge at the 11th hour. Just about to start building my first trailer, but need some advice first. I already have, wheels/tyres, suspension kit, axle, brakes (hydraulic - sorry guys, i see these are less favoured), and the design i need, however, help in setting up the drawbar would be appreciated. I would like to know the disadvantages in welding a solid beam to the front chassis member, with a couple of supports coming off, running to the front corners. I have tried to attach a simple paint program drawing of what i am thinking. This is only the first third of the trailer - the middle section is raised to go over axle etc, and then lowered at the rear again. This design would suit me best as i need to make the front and rear sections of the trailer as low as possible. Also, planning on using 75x50x3 for drawbar and entire chassis, thoughts?
Thanks alot for any information you may be able to offer.
Tim.

Hey Tim, Welcome aboard.

Any chance of a piccy of the rest of the trailer design, just to see how it all ties together.

I'm a little concerned with the drawing you've done as I'm no fan at all of drawbars that don't tie right back to the front spring hangers. What's the trailer going to carry, as it sounds interesting with a front and rear drop...

Hi Yonnee, thanks for the reply - as i have done some reading, you are the guru on these matters, and have seen that you are not a fan of the design i posted - hence asking for your advice. The trailer is designed to carry two go karts - but will only carry one most of the time. It also has 2 sleeping compartments ( one for the wife and i, the other for our son), with a bit of space left over in the middle for all spare parts and some cooking facilities. The reason i want to have it lowered at the front and rear is allow enough room for the karts to fit in under the sleeping areas, having enough height in the sleeping areas (minimal - but relatively comfortable) but still allowing me to park it in the garage. I have attached a side view of the trailer (sorry - simple paint program again) with dimensions. This will allow drawbar length of 1600. Please note in your advice, that the drawbar will need to support a bull nose as such. The weight - and payload will be extremely light - no heavy objects. The trailer will be entirely enclosed - apart from where i have noted that sliding doors will be in place. (The drawbar is obviously off to the left of the picture)
Thanks for your help.

I think yonnee would agree that this design is tried and tested;

Attachment 150718

Attachment 150719

I see by your plan the trailers going to be about 4300mm long. With 1500mm drawbar added that's a 5800mm long trailer. Not a small trailer by any means. I'm still working on my trailer that's 6000mm long. My frame is 75x50x3 rhs and drawbar is 100x50x3 rhs. Although strong enough for my purpose, looking at it now I would have gone to 100x50x3 for the main frame. Super overengineering!

Hi Dazzler, thanks for your input. From the picture you supplied, there is no doubt that this would be the preferred method. I might be able to squeeze the drawbar in under the front part of the chassis, however, i would still need to raise the middle section, any thoughts on how to do this? I was thinking possibly chassis coming up at 45 deg angle to front hanger, then back down after the rear shackle? Would this compromise anything structurally? My biggest issue is that the front and rear is lower (by alot) then the middle, and therefore i can't get the drawbar back to the front spring hangers. So simply asking, is it better to weld the drawbar under the first third of the chassis then my original idea? Once again, simple paint picture - ideas - would this not 'just work' but be strong and reliable? Of course, everything would have supports - probably more than what is needed, but just to be safe. All help is appreciated, as i need to get started a.s.a.p. (would like it to be ready before next year). Will start taking some photo's and post the progress if people are interested - there won't be anything else like it on the road!!
P.S - buildspacetrain - i like the idea of 100x50x3 for the drawbar, but will probably keep the frame at 75x50x3, unless i'm persuaded otherwise.
Cheers, Tim.

...so I'm not going to write a detailed reply right now, but I did throw this together as food for thought.

Attachment 150826

Slope the front for better aerodynamic efficiency.

Sleeping quarters at the front, the young'un up the top. (they usually like to climb things, and wont need as much room and be hindered by the slope.)

Be mindful the most weight is forward of the axle(s) when mobile.
I like Yonnee's design as it solves the drawbar issue. Not sure if most of the weight is now behind the axle?

Wouldn't 150mm ground clearance be to low with 1850mm overhang?
Stuart

Originally Posted by buildspacetrain

Be mindful the most weight is forward of the axle(s) when mobile.
I like Yonnee's design as it solves the drawbar issue. Not sure if most of the weight is now behind the axle?

I had thought of that, and I took a couple of things into consideration;

• Go Karts do not weigh alot (around the 80Kg mark), and Tim stated that there will only be one most of the time.
• The fixed weight forward of the axle such as the internal fitout for the sleeping quarters, along with the bedding, etc., and any kitchen fitout should balance out even two go karts.
• The axle would be a little further back than the standard 1/2" for every 12".
• I've added a spare to the front as well.
• With the front not being so low, a caravan water tank could be added just in front of the axle.

Originally Posted by Stuart

Wouldn't 150mm ground clearance be to low with 1850mm overhang?

Probably... depending on how steep the driveways are you're trying to enter/exit. But legal requirement is only 100mm.
Also, if the wheels were placed just forward of the Karts, the the rear overhang would be closer to 1500-1600mm in this case.


A bit more of a play this morning.
The top bed running accross the front allows both people in the bottom bed to sit up, making getting in and out of bed a little easier.

Attachment 150893

Hi guys, thanks for the advice. And Yonnee, thanks for the pics. Might run with your design as it allows for a structurally stronger setup....and at the end of the day, that is what is needed. Just a few more questions in regards to the weighting. Although the karts do not weigh alot (80kg is pretty spot on) there will be a fair bit of weight in the centre cargo area. Mainly toolbox & spare parts, and then the kitchen fitout. I will be having deep cycle batteries (heavy - same weight as toolbox) & most likely solar panels flush mounted in the roof. Having raised the front section - it will allow to build underneath as such for more storage (light, bulky objects - kart trolleys etc...). However, the main question is, where would you suggest mounting all the heaviest objects? - i would think directly over the wheels - spread evenly across the width. All the lighter objects won't really influence the set up too much.

There'd be nothing stopping you from having a sunken section between the chassis rails. Could be somewhere for the batteries to go.

I'd go with your thinking on having the heaviest stuff over and near the axle, particularly with a single axle trailer.

You could set the trailer up one of two ways. Have an internal kitchen fitout such as a caravan, but that might leave it a bit tight for room inside. Or, have a slide out kitchen, like a camper, and have an annexe you could attach to the side of the trailer as your kitchen. This'll keep cooking fumes out of your bedding. I'd have the slide out section over the wheel arches, and use the space between the arches for parts storage (have it facing the karts).

Thanks for all the help Yonnee, it's greatly appreciated. The section between the chassis rails was always going to happen, but with your advice, i'm confident this will be a much better design, and last a lifetime. Being new to the forum, is there a better place to post pictures of the progress? With the design finalised, it's time to start cutting some steel!!! Posting pictures will allow other users to voice some opinions - i'm always open to suggestions. Once again, thanks mate.