View Full Version : Help needed to design a...

Wild Dingo
31st Mar 2007, 01:35 PM
Yes Im working on behalf of a fellow woodbutcher whos in need of a xar trailer cum workshop for when she begins her new life as wandering turner headin out of Darwin

If you havent seen or met her Robynmau posted an intro HERE (http://www.woodworkforums.com/showthread.php?p=487804&posted=1#post487804) And Ive taken the liberty of seeking your assistance in designing her trailer

Yes Im a cheeky buggar and no she didnt ask me and yes I reckon its a good idea if only to get you workin on a more detailed LARGE scale thing :;

Now Im assuming the average small car length is what about 10ft... so Im guessing the plan is for a 15 to 20ft trailer behind the winnibango as they tour around Aussie {personnaly Id go 20ft but thats me... mmm on second thoughts I wouldnt cause I wouldnt be able to fit all the tools in 20ft! :doh: }

Weight would be the biggest issue particularily getting it over the axles where it would be best placed... so to achieve this my first suggestion is the vehicle runs up into the trailer on ramps that have a sliding door to cover the back end right? with me? okay the front section that which would include the workshop would have heavy storage items backing onto a wall between the car and workshop... putting most of the weight over the axles... still with me? goodoh... say timber or the lathe itself along with chainsaw bandsaw small jointer some planes saws clamps etc a small width but full length wall bench along the front wall of the trailer (winibango end) holding bits and bobs... maybe timber storage?

mmm thinking... maybe the lathe could be on a sliding stand so she can slide the thing out and lathe outside under the boab trees?... and while Im thinking a small air con over the bench would be a good idea... what about lighting? so shes gotta have a genie (size small but powerful enough to work the lathe plus lighting) mmmm what else? racks down either side of the car say above window height... so how highs this trailer? well lets look at the height of a winibango for a starter... what say 2mtrs? so a small car is how high? 1.6mtrs? damned if I know I drive an F100 what do I know of small cars?... okay thats anothery for yous blokes... so racks above the car so she can store stuff (ahem she is a woodbutcher!! Ive never met one yet that aint a hoarder) so what else?... mmmm?

Okay so Ive given the seeds of ideas here now fellas over to you!! Nope I a) dont have the time to buggarize around with the program b) no interest in becoming so frustrated with the program I throw the laptop in the corner in disgust so Im givin it to yous mob...

Any takers?

31st Mar 2007, 02:11 PM
righteyo, fire away!:D

Wild Dingo
31st Mar 2007, 02:19 PM
Quick buggar aintcha!! :U

so first problem is the width... to wide mate come down to about 8ft 2in I think thats pretty much the standard width before she would need to get a permit in each state to tow it

Next the length 30ft??? strewth!! I was working on 20 maybe 24ft take into account the length of the winnibango mate and youve created a bloody semi trailer rig! :C this could then create another licensing issue for her in that some galah in one state or another would make her sit her semi license to drive the thing

mmmm okay height? mmm I reckon your about right there given the height of a winnibango

Keep at it me ol china yer doin well :2tsup:

joe greiner
31st Mar 2007, 03:20 PM
1. Use the space above the car bonnet for a storage mini-loft.
2. Add a door on the driver's side of the trailer to accommodate the open door of the car; otherwise you either have to push the car in, or climb out the window and then slither through the trailer to the back.
3. I think even small cars are more than 10ft long.


31st Mar 2007, 04:34 PM
what about this then for overall dimensions?

What is going to be towing it?

Jim Carroll
31st Mar 2007, 05:19 PM
You would only need 6' internal height. You are working outside most of the time.
Take the walls out to the outside of the wheel arches, gives more storage area.
Put a nose cone on the front, another storage area as long as it is light gear because when they check they go by the ball weight.

31st Mar 2007, 06:02 PM
Having driven the car in the box how do you open the door to get out.

Wild Dingo
31st Mar 2007, 09:18 PM
what about this then for overall dimensions?

What is going to be towing it?

Im not sure but I think the overall width is around 8ft 4in? including wheels and wheel arches... as I said Im not sure but think thats the way its done

A winnibango

Id imagine one of them all in one units... dont know the motor size as she didnt say... an mate Im only tryin to get things rolling here.. I'll give her a hoi an see what she reckons when she reads the thread

Joe I'll go measure the missus proton "beast" an get back to you... not sure shes got a proton but hey its a small car eh! :;

Wood Butcher
31st Mar 2007, 09:53 PM
For the vehicle widths, the max width allowed is 2.5m (8ft 4in) as per the australian vehicle standards bulletin (http://www.dotars.gov.au/roads/safety/bulletin/vsb1/index.aspx)

There is also a maximum length of 12.5m but that incorporates the towbar length as well.

31st Mar 2007, 10:29 PM
sell the car and buy one of those double decker buses, kit it out, and precilla queen of the woodchucks here we come.....simple:2tsup:

joe greiner
1st Apr 2007, 02:22 PM
A lot of the snowbirds we see around here have the motor yacht towing the car. Don't know the brand, but they use a nifty tow bar that folds back against the front bumper; doesn't have to be removed.


journeyman Mick
1st Apr 2007, 03:38 PM
Does it really need to be a fully enclosed trailer? That's a lot of extra framing and sheetmetal (= weight) plus mucking around building doors etc. On something that size the frame will wrack a lot against the doors which don't and you get stress cracks in the framing, chafing of metal against metal with resultant ugly rust marks.

I reckon that an open car trailer with a box on the front, shaped for air flow would be the go. The box can house all the "toys" and will protect the vehicle from stone chips and should deflect most of the diesel haze around it.

The starting point of the design exercise should be the what the maximum weight of ther trailer can be. The tow vehicle will have a maximum allowable tow weight, plus a maximum GCM (Gross Combination Mass). You'll need to know what the gross weight of the mobile home will be when fully loaded (fuel, water, food etc etc) to see how much of the GCM is left to play with, because with some vehicles Gross Vehicle Mass + Towing Capacity is greater than GCM. ie, you can have a fully loaded trailer or truck, but not both. Next thing, have either of the drivers had much/any experience driving a combo of the length and weight we're looking at here? Do they want to go to the trouble of getting the appropriate licenses? Do they want to drive a heavy combination around the countryside? It's a lot more tiring than driving a car, requires more concentration, room to maeuver, space to stop and park, fuel, registration, etc etc etc.

Once you've gone through all of that and you knwo how much your trailer can weigh and how much the run around will weigh you'll need to look at appropriate axles, springs and brakes and the weight thereof. For the dimensions, the first thing you need to know is what size the vehicle will be. It's going to be aq very different trailer if you want a Suzuki Jimny as a run around as opposed to a Pajero.

I would look at paring down, as much as possible what's considered a must have to bring along. I'd try to fit it all in the tow vehicle and just have a small run around riding on a two wheel dolly trailer and a protective "car bra" fitted to the runaround to minimise stone chips etc.

A large heavy trailer is no fun to tow. It's not for nothing that trailers with rigid draw bars are referred to as "pig trailer" in the transport industry. Trailers with drawbars that swivel the front axle(s) are called "dog trailers" because, like a good dog they'll faithfully follow you. Towing a heavy pig trailer is like trying to take a pig for a walk on a lead, it's hard work and the pig wants to go its own way.

Actually, I'd look at whether a ruanaround was strictly neccesary. Think about push bikes, motorbikes or even motorised push bikes.


Chris Parks
5th Apr 2007, 12:09 PM
Does it really need to be a fully enclosed trailer? That's a lot of extra framing and sheetmetal (= weight) plus mucking around building doors etc. On something that size the frame will wrack a lot against the doors which don't and you get stress cracks in the framing, chafing of metal against metal with resultant ugly rust marks.

The answer to the racking and general skin movement on the frame is glue. I have just built a second enclosed trailer which has very little framing except around the dorr entries and mid length along the sides, though it is smaller than the one proposed. The first one showed signs of cracking around the rear door and was not rigid enough, the second was bonded with Sikaflex and it is rigid. We glued everything including the floor to the chassis and it is far better than mechanical fixings of which some were used but not many. All the panels were made in a CNC controlled sheet metal factory including the chassis members which we folded ourselves. Just remember it must be complianced before registration so I would tackle that issue first as we had to get ours inspected by a certifying engineer before the registration authorities would look at it.
As to the woodworking part of it, don't forget to allow for exhaust extraction, this will need it as the air will be stalled in a very small area with the same amount of dust as in a larger shed. It is going to weigh A LOT and I would be sitting down and carefully working out if the finished trailer was towable legally with the intended vehicle. There are small and large Winnebagos and it will have to be one of the larger ones to have a trailer of this size. I drive trucks for a living and don't think I would like to drive around Australia towing a trailer of this size if it were me. I wonder if there is a legal allowable length limit on something like this?

5th Apr 2007, 02:27 PM
If it were me I would talk to the manufacturer, Winnebago, they should know the GCM etc.
There are quite a few of them towing trailers and would be able to advise where to start.

5th Apr 2007, 08:48 PM
As an ex-trucky the best advice I can give is that this must be made by an engineer, one who knows what he's all about in the trailer world. :D

The old 8 feet and 2 inches wide was the absolute maximum allowed for the drivers side mirrors. If the trailer is that wide, the mirrors will not mirror the road behind your trailer. This unit will be daunting to drag along, especially if these people are inexperienced tow drivers. For a load of tools and stuff, the construction will need to be stronger than a caravan. A cross-wind, or one from either front corner will test the drivers skill.

In any case, recent trailer law changes have been made in most states, and if you visit your local State Transport Department website, you can find all of the info required. Don't forget your licence, does it caover the wieght and combination? :(

Something like this will involve special tow bars, full braking system and the overall length of both tow vehicle and trailer as well as weight, both laden and unladen . . .blah blah blah. After all, it is the Government who has all the say in this matter. After them comes the insurance man. :oo:

14th Apr 2007, 06:15 PM
Hi Folks

Now I'm back from Brissy, I thought I'd stick my nose in to say a very big 'Thanks' to Shane and everyone else for showing interest:U

As explained, hubby and I are off into the wild blue yonder later this year and I don't want withdrawals from woodturing, so part of our trailer will become my workshop.

We are curerntly working on the motor home side of things - refurbishing a 40 foot [11m] Austral Tourmaster for our living quarters [has 3 axles]. That's been quite a challenge as we raised the roof and found extensive [total understatement] rust on the frame but we're almost there now yeh ha :! :! :! Fortunately, driving this rig isn't a problem for hubby as he has the required licence [fractionally rusty but won't take him much time to refresh his skills]. I want to learn too, but he's resisting at this stage so I haven't pushed the issue too much [yet :;], will wait till we're on the road and see how we feel about it then.

As we have a total length of 19m for both bus and trailer the trailer can only be 8m from tip to tail. We have a Nissan X Trail, which you can see with take up a fair bit of space and weight:

Length 4.455m
Width 1.765m
Height 1.750m
Tare Weight 1500kg

We thought we'd make the trailer lower than the bus, a maximum 3.5m high but stay at the same width which is 2.3m wide. We've discussed buying an earth moving equipment trailer as a starting point as it could hold the weight we want to put on it, but haven't found one in Darwin yet so that's still on the backburner. We will got to a local trailer builder if nothing else comes up. Either way, it will definately be fitted with all the necessary safety equipment and meet government regulations.

At different times we have talked about whether to close the trailer in or leave it open where the car would be, so your thoughts about the additional weight closing it in and being able to get out of the car after parking it in the trailer were appreciated. Perhaps, there is some way to close in the top 1.5m of the trailer to use for storage, but keep the sides open. The open sides would solve the problem of being able to get out of the car easily. I did think about putting a false floor under the car but hubby reckons we could finish up too top heavy so that probably isn't the best option.

All along we've been looking to have some way to lock the workshop up, but at the same time be able to swing the Nova 3000 lathe out so I can turn without having to 'lift' it, but also we don't want wood shavings and dust flying all over everything else that's on the trailer so some sort of partitioning would be useful. Also, shade and lighting are definate requirements but should not be too hard to organise:B

Now you have the full picture, any thoughts on the matter will be appreciated.

Thanks in advance



journeyman Mick
14th Apr 2007, 06:27 PM
The tare weight of the X-trail, did it come out of the handbook and have you fitted any accessories? Usually the tare weight is the basic vehicle as it rolls off the production line, plus oils, coolant and half a tank of fuel or so. If you've added bullbar, towbar, racks, lights fridge etc etc this will all add to the weight. You might want to load it up as it is to be towed and put it over the weighbridge. Then you need to take that figure to the trailer builder as a starting point, along with the maximum length, width and height. I reckon you need to go a bit Zen with this: less is more. :wink:


Chris Parks
14th Apr 2007, 06:36 PM
Is it your intent to have the lathe inside the trailer when you are working? As I said in an earlier post dust will be an issue, more so than in a shed. Build a "box" on the front of the trailer sufficient for your workshop needs and leave the xtrail in the open. I hope you never have to reverse with the trailer on, that would be a bit tricky and that is from someone who drives trucks for a living. The first thing I would do would be out a reversing camera on the bus looking at the trailer.