Thread: Car Trailer Dolly Q's

something like these trailers would be cool but they look heavy, anyone know what a 4x1.9m caged trailer would weigh? any idea even on what material to use on the cage? if i went this route should i go one or two axles to keep weight to a minimum?

If you are using something like Sketchup you can get a fairly good idea. My trailer came in within about 50kg of my estimates at the weighbridge and the steel structure would have been within 5kg probably.

Originally Posted by gazza2009au

what a total^$*( up unbelievable after going to buy the steel today RMS finally emails me back saying a tow dolly is illegal in NSW however i can use a towing A frame i thought u beauty ill build one of those than comes the bit u need to jump thru the hoops to get it, first off the A frame needs brakes? i donno about this.... than u need both vehicles, the tow and towing cars inspected for a match up for towing and i think someone needs to sign off on it too

i may just build a flat bed with the steel i have on hand now

http://www.rms.nsw.gov.au/documents/...ame-towing.pdf

Yeh its been a while since I've been back to this thread ....... I just have to say .......
..............."I told ye"

as for a couple of the other issues raised.

You need to understand that trailer parts for the most part are cheap and nasty and run to narrow safety margins.

Axles in particular don't have much engineering margin so ya best not pushing the friendship.

I would not run less than a 2 tonne axle ... that means land cruiser bearings ... as a single axle on a trailer such as this.

there are pro's and cons for single and multiple axle configurations ....... more lower rated axles means smaller wheels and lower ground clearance ...... AND ..works out cheaper mostly.

multiple axles also ride smoother because each wheel takes most bumps in turn.

Multiple axles do not manover as well as a single axle.

As for running without suspension ...Yeh I that is very much frowned upon ...probably illegal in most states.

As for a trailer never being over loaded

cheers

Im pretty gobsmacked by this thread, this is the reason why we wont be allowed to build our own nice trailers in a few very short years.Do you have a plan?

Yeh ... the whole home built trailer thing seems a bit scary to some ........ but ya know what the scary thing is ....... most of the home built trailers are better built than most of the commercial units.

Its all pretty straight forward ...... start by reading VSB01


cheers

Originally Posted by Aufitt

Im pretty gobsmacked by this thread, this is the reason why we wont be allowed to build our own nice trailers in a few very short years.Do you have a plan?

im offended by this post some things are best kept to your self dont you think?

Gassa mate you have a good reason to be a little bit offended .... but only a little bit ...aufitt raises a very valid point and one that "big trailer" no doubt gives an airing at regulatory meetings every damn time.

Any muppet with a welder can go and build a trailer and get it registered.... I am sure that worries some people.

BUT the truth of the matter is ...... inspite of all the issues surrounding light trailers, the risk from them is shown to be statisticaly very very low so much that they barely show in road accident statistics.

However .... any reasonably competent welder can build a satisfactory and safe trailer ..... provided they do a little homework ...... and VSB01 and the trailer components suppliers can provide most of the information needed.

Another truth is ...... a very large proportion of the commercially made light trailers contain almost no formal engineering short of that supplied by VSB01 and the components suppliers ...... AND those designing and constructing them require no formal training, assessment or licencing.

If you want to be concerned about some sort of light trailer issue, in my mind there are two very real issues that predominate .........

The rediculously high towing capacities that are being published for some pessenger cars and light commercials ...... that allow them to tow rear hitched pig trailers considerably greater than their own mass. ( rear hitched pig trailers are known to be a fundamentally unstable format and frowned upon in heavy transport for this reason)

The licencing system that while it requires a higher level licence to drive a rigid vehicle over 4.5 tonnes allows a person with no more than an automatic passenger car licence ( and no further training or experience) to drive a 9 tonne vehicle and trailer combination on the public roads.....AND an over dimension one at that.

Cheers

Originally Posted by gazza2009au

im offended by this post some things are best kept to your self dont you think?

Yes I could have kept it to myself, but maybe it might inspire you to form a plan and a budget, and build something that is future proof.We are lucky to have such freedom in homebuilt trailers that potentially are an accident waiting to happen, this WILL change.You have a can do attitude, this is good, but without a plan before even thinking about cutting steel, I don't want to share the roads with it.There is good reason why 2000kg+ car trailers cost $10k and above, I will build one after my current build and its up to me to ensure duty of care.This forum is good, you've had sound advice so far.Report me to @Yonnee and have me banned if my concern is your concern, I'd wager he may raise similar points and steer you on the right path.Cheers.

Gazza, I appreciate that you have been offended by some recent comments, so I apologise in advance - but I am coming from a background of 20 years running my own fabrication shop and spent 225hrs course time at TAFE learning MME, MIG and TIG welding.

You raiseUntitled-1.jpgd questions about the quality of your welds and rightly so. I can only comment on the images you posted in post #44 and have copied one of them here. This probably one of the better examples you posted - but it does not look like it is the quality required for this project. I have identified 3 problem areas:

A. The weld does not cover the edge - there should be a continuous weld around all 4 sides and corners. By itself this is not a major issue but will provide a point for moisture entry resulting in rusting and weakening of the joint.

B. Weld is not continuous along its lenght. Yes you can stop and restart, but these voids suggest poor technique that has resulted in weak points in the weld.

C. This is the most damning issue and I would immediately 'fail' the weld because of it. Apart from the weld being ended before the corner, the image is showing that the weld has barely penetrated into the 'junction' of the two pieces being welded. It also appears that your technique is a problem and that you are not getting the heat right into the joint - I see 2 heat points; one on each section of tube being welded, but no evidence of the molten weld pool at the junction of the two pieces. This suggests that there is very little penetration and the 2 pieces are basically only 'held together' at the outer edges of the weld .

There are a number of causes other than technique which may cause / contribute to your problem:

* Insufficient gas flow perhaps coupled with inadequate pre / post purge at beginning and end of welds.
* Wrong type of gas - check with the gas supplier as to whether the gas you are using is the recommended type for the material you are using.
* Incorrect filler material ( probably the least likely cause)
* Current set too low - for the last 5 years before I retired I welded aluminium almost exclusively, so I am a but rusty on the correct settings for steel tubing, but for 3mm wall thickness I would be thinking of something around 180 -200 Amps.
* Incorrect or variable torch travel speed - easily seen by the sides of the weld not being parrellel.
* incorrect filler application - too much, too little or feed not consistent.
* Inadequate duty cycle of the machine - some of the cheaper Chinese inverter type TIGs only have a 20% duty cyle at near maximum Amps. This increases the need to stop/start welds rather than being able to run the full lenght of the weld in a single weld.

While these things, and possibly some others, may be contributing to the quality of the welds, I really beleive that you main problem is in your technique. Practice, or get some tutition,- starting the weld and establishing the proper weld pool before applying filler and starting to move the torch along the run; maintaining the weld pool in the junction of the joint; and finishing the weld without ending with craters. Start with flat butt welds and when you have finished the weld turn it over and ensure that you have full penetration. The weld should close the full thickness of the material - no gaps between the 2 pieces on the back. You will also need to be proficient with 90 degree fillet welds, as well as up-hand, down-hand and overhead butt and fillet welds on a project such as this.

I am curious as to why you are using TIG. Personally I would prefer to use MIG and I think that the majority of welders would also use MIG by preference for this type of project. But you could use TIG if the machine is up to the task, it will not effect the structural soundness of the welds, but may take a fair bit more time and cost quite a bit more for gas.

There is no reason which would prevent you from building this project at home, but it certainly is more difficult to do than it is in a properly set up factory. But wherever you do it, there is no difference in the quality of the workmanship required. You can do it, but I seriously suggest that you improve the standard of your welding before going any further -from the photos submitted the welds do not look as though they are up to the standard required.

I hope you take these comments in the manner in which they are given and wish you success with the project.

Bob