Re: Mobile Harbour Cranes Vs Fixed Type Cont. Type Ship Unloade…
Dear Libran,
I agree with you regarding the limitation of Mobile harbour cranes since time is consumed for placing the grab on the material, slewing and placing the grab on the hopper. This operation is also associated with spillage at the hopper end.
For flexible operations, one may try bridge type (rail mounted) grab unloader. With a suitable grab, desired unloading rate could be acheived. For multiple operations, arrangement is available on this type of equipment, wherein, grab can be detached, either a hook block or a magnet can be fixed as required. The boom may be extended towards the shore for picking/unloading material from the land side.
We had one such equipment for handling the following:
1.0 Unloading dry bulk - with a grab
2.0 Unloading Scrap - with a magnet or orange peel grab
3.0 Loading HR coils with coil hook.
Regards
K. V. Subba Rao ■
Mobile Grab Crane
Dear Anil
I fully agree with Mr Subba Rao Mobile harbour cranes are not suitable for capacity Required. You may go to Rail mounted Kangaroo Type Grab ship unloader . However 1500 tph coal is on higher side for this type of unloader.
A R SINGH ■
Gantry Container Crane Vs Harbor Cranes
If you have already the container cranes you will need to fit them with electrohidraulic grabs, it will affect the capacity of the container crane, also the coal unloading will generate dust and for sure will affect the mechanical parts who are not designe to operate under dust enviroment.
If you have an ocasional unload operation it can be useful but if you will unload coal or other bulk material for a long period of time you shall think to buy new cranes prepared to operate under these conditions and most of the mobile cranes are prepared for it.
Also you shal consider the berth piling distribution if it is able to place a mobile crane outriggers, some times not are distributed proportionally with the berth piles. ■
Re: Mobile Harbour Cranes Vs Fixed Type Cont. Type Ship Unloade…
Once again we are gasping for definitions of the equipment we purport to discuss. There is no such thing as a continuous ship unloader: hold clean up activities: overhanging coaming: tidal adjustments etc all contribute to discontinuty.
Slewing a grab full of coal is no more detrimental than shuttling a grab full of coal. The dedicated grab unloader has survived because..it can sometimes outperform the fancier digging,sucking,screwing,digging sucking and squeezing even machines which are, by nature of fancy, somewhat less reliable.
Bigger machines mean bigger problems: lots of them carry add-on harbour cranes..just in case.
If you throw 40' containers about at grab unloader speed you had better check the insurance policy, i.e. it is not as easy as it seems to adapt a container crane into a grab unloader. Container berths are highly organised places anyway and should not be obstructed by bulk handling paraphernalia.
Use ordinary harbour cranes.
'Continuous' unloaders are abberations of the good old coal bunkering cranes which can be referenced in most Maritime Museums eg @ Liverpool. ■
John Gateley johngateley@hotmail.com www.the-credible-bulk.com
Mobile Harbour Cranes Vs Fixed Type Cont. Type Ship Unloaders
I need the expertise from the hon. members of this forum to give their expert comments on the following --
Up till now availability of high capacity mobile harbour cranes(with grab) (rated/final cap. up to 1500 tph) was not their/ very less in the market,if we will use rail mounted cont. type ship unloader (to unload coal from 80,000 dwt ship) in the place of mobile harbour crane,definately with this machine we will not get more more flexibility comparing with mobile harbour crane.Any comments?
regards, LIBRAN ■