Overhead Gantry Cranes

[joel89]

yes ive mentioned all this to them before silva foxx,, but nothing happens and when the job is stood we have to just do it.. pretty much a joke of a company to be honest but anyway

 

[Knobhead]

Just because that's the way it's always been done neither justifies it as safe or correct practice. Today we have to challenge old ways of working.



Had you informed your site H&S or made any attempt to action the said issues, or refused to carry out an unsafe task?

SF, that's all well and good, when it's not you're job.

All companies will have a health and safety policy. Even with the multi nationals I’ve worked for, wealth and safety rules come first.

 

[joel89]

love it tony.. nail on the head !

 

[Knobhead]

I’ll help where I can with crane control, but it’s a vast subject. Some of it is totally illogical.

God help you if you ever come across Allen West control. One motor driving up, on the same shaft is another larger motor driving down! (It stops the load going in to free fall. Not fun when you have 40T on the hook)

I meant what I said, learn to drive the crane first, then you know what it’s supposed to do.



Funny how we set off at loggerheads but we are now singing the same tune.

Life is strange!

 

[joel89]

I’ll help where I can with crane control, but it’s a vast subject. Some of it is totally illogical.

God help you if you ever come across Allen West control. One motor driving up, on the same shaft is another larger motor driving down! (It stops the load going in to free fall. Not fun when you have 40T on the hook)

I meant what I said, learn to drive the crane first, then you know what it’s supposed to do.



Funny how we set off at loggerheads but we are now singing the same tune.

Life is strange!

all our cranes are on radio remote controls, so i do a lot of lifting, i have been on a slinging and lifting course as everyone else has/ does in the factory, yeah that does sound a very awkard system and rather confusing.. haha yes are on the same frequency now !

 

[joel89]

Question for you tony, why are all our panels wired with fuses on all motors instead of overloads and breakers? Any reason or just how they been fitted theyre new panels too

 

[netblindpaul]

Breaking capacity?

Personally I prefer breakers, but, it would also depend on the manufacturers instructions for downstream devices.

I am surprised that there are no overloads, mind there are some these days that do't look like overloads TBH.

 

[joel89]

I no paul i buy schiender breakers and overloads built in, i dont like MCBS or fuses on motor gives no thermal protection, !

 

[Knobhead]

Hoist motors in particular need the coarse protection fuses provide. Do you want the hoist tripping on a load pick up? A normal motor overload unit is far too sensitive. Bear in mind, the motors are “crane duty”, built like the proverbial “brick s***house”.

Go on to large cranes, there will be no fuses at all. Sod anything stopping the hoist drive, it has to keep going. Even grossly overloaded they keep going.

During a deflection test the crane is required to lift 175% of it SWL. The motor grunts, but just gets on with it.

 

[netblindpaul]

joel,
I would normally always use overloads on motors, possibly fuses, possibly mcb's depending on the application, some client specs call for both.

Tony,
I have never designed crane controls and would not normally get involved TBH, I had not considered what you have said TBH, and it does make sense.
Mind, I have worked on repairing a few where the motors were not "crane" duty as you describe it.

 

[Bobster]

The hoist motors are set up along the lines of fire fighting equipment. It's safer to have it burn out rather than trip during use.

 

[joel89]

I thought that may have been the reason on the hoist, cheers tony for clearing that up, Paul if you have never done crane control not much point commenting lol

 

[Bobster]

By the way on larger motors bs-88 motor fuses are by far the best form of S/C protection. Usually coupled on newer gear with electronic overload units.

 

[Bobster]

I thought that may have been the reason on the hoist, cheers tony for clearing that up, Paul if you have never done crane control not much point commenting lol

Also this, defiantly not the right attitude to have.

Paul is a very experienced electrician.

 

[netblindpaul]

I thought that may have been the reason on the hoist, cheers tony for clearing that up, Paul if you have never done crane control not much point commenting lol

What I said was joel, that I've not designed crane controls, I have repaired them a lot.

Control design is a large part of my business, very little of what I do comes under BS7671, so I do have a lot of competence in control system design.

If you like I'll stop commenting completely, that's fine.