QUESTION TIME

Surely those safety cutout swiches they have to install on DG registered vehicles would completely isolate the system?? Most of the ones I had anything to do with isolated both the positive as well as the negative when installed between the battery and the main system. So, my way of thinking would be that unless you arced from the welder handpiece to the main alternator to battery lead, you should be OK??? Only takes a minute or two to remove the main lead from the output post on the rear of the alternator itself??? Dave

I dont know if thats correct Dave as the earth lead of the welder is still clamped to the vehicle


I agree, about disconnecting the alternator, and yes it only takes a few minutes to unscrew the main connection and unplug the rest

What bought this question about is I'm doing a lot of welding with things supported or even hanging fro the front end loader and like always I disconnected the alternator

Some jokers laugh at me for this, until I learn better I guess I'll keep doing it, it only takes a moment and the I know it's safe for the alternator


Thanks for the replies


Paul

Well you can look at it this way. While you continue to carry out your work safe practise you know for certain that you will not do any damage.

That's my thinking, thought someone may have known for sure

Paul

With a plasma cutter n a Mig welder we @ times grind the paint or rust away to get a good contact with the earth clamp n then put a nother clamp over the top of the spring loaded earth clamp .... or we tak weld the earth clamp to the job
coz if U aint got a good earth the current can go all round the truck / trailer lookn for the earth contact
cya

I have never bothered disconnecting, unless you are welding on the engine block and have the earth attached to the chassis with poor grounding I don't really see how it would cause grief as you are not using the engine electrics as a conductor. although on a side note my backhoe calls for diodes installed on both sides of the solenoids for forward and reverse. the reasoning is that the induced current from the coils unloading causes pitting to the contacts on the steering column and possible alternator damage. as Paul says same as coil and points.

As a industrial Electrician and as a trade qualified welder (with a lot of gap years driving trucks), the amount of damage I have seen in factories and large workshops to switchboards and other electrical equipment by welders not taking care with earthing over the last 50 odd years would stagger you, when it comes to earthing electricity is weird shit, we will not get into voltage rise in the black wires, if I am welding around an electronics (diode are electronics), I disconnect every thing I can, disconnect is 10 time easier than replacement and 100 times cheaper

I have been watching a heap of those Pakistani truck repairs videos where they take a write off and with an oxy, stick welder and big hammer rebuild it looking like new.
I notice that the majority of the trucks are hydraulic brakes, Is it common overseas for even a bogie drive tipper to have hydraulic rather than air brakes?

Cheers

Electronics are expensive to replace,so why fry them?........I recall when people would import big (ugly) Jap bogie tippers and special body trucks......always had big hydraulic brakes .....as to electronics...was hearing about frying the computer in a CNC lathe ,by TIG welding near it........seems the HF in the TIG is to blame........another interesting ,but useless fact ........the electromagnetic surge from a nuclear explosion frys solid stste (transistors ,diodes etc)...but doesnt affect glass valve (thermionic )electronics.......so the Russians used old fashioned valves to nuclear proof their weapons.

Nuclear blast frying electronics was standard advice during the cold war which was why the poms (and presumably other western allies duplicated all communications. They now seem to be in self denial. Don't know about Russia using valves for that reason. Before the fall of the wall there was actually a law stopping the sale of washing machines and fridges to Russia so that they couldn't get their hands on the micro chips in them for weaponry use.