Ship loaders were originally used to bunker coal fired ships & then somebody saw their potential for loading the bulk cargo holds. Like you say there isn't a lot said about them because they are much less intricate than ship unloaders.

Essentially a boom conveyor is fed from a tripper in a wharf belt. The 2 are usually mounted on separate undercarraiges where the boom conveyor vehicle tows the tripper bit.

There should be a spout at the discharge end of the boom to direct material & contain the dust generated during the material descent into the hold. This same machine can load bagged material if a spiral bag chute replaces the spout. In the hold they used to fit a slinger to trim the cargo. This was a high speed, high maintenance dust generator which nevertheless fulfilled its intended duty. Nowadays we prefer to fit an actuator on the end of the boom & this kicks the spout, imagine a knee joint, to reach under the hatch coamings. Can somebody please please define the spelling of the bit that runs along the top of the hatches to the hull? The outreach boom usually slews as well to give better, some claim full, coverage of the open hatch area.

The usual tedious manouvering around the ship superstructures is common to all loaders.

There are also some real classy monsters which can dump 10,000tph into big ships & can cover the whole hatch area by a combination of slewing & crowding the boom; although boom is not adequate to describe the structural excellence of the system. Articles in Bulk Solids Handling by Soros will give insight into these beasts. Some travelled on a circular track, on a curved jetty out in the roads, while one boom was carried along a straight track with a sliding link, rolling in practice of course, which accommodated the chordal shrinkage. Both types of machine employed crowding & slewing to cover the holds of the biggest ships available. There was a Foster Yeoman machine built about 1986 by Strachan (peversely pronounced as Strawn, by them) & Henshaw. It loaded granite out of an island cave worked into one of the Hebrides (not pronounced He Brides by anyone who expects to leave Scotland in one piece). That machine movement was/could be radio controlled from a module carried by an operative on deck. Radio control from the deck has been discussed in these forums a few months back. The clear possible benefits have to convince the nautical legalities before it is universally adopted, as far as I know to date.

On your other note; in the thread context; bucket elevators (see Heyl & Patterson, PO Box 15 Pittsburg. How can you forget such an address?)dig material directly out of the vessel hold & deposit it onto a conveyor which takes it over the ship's rail.

The bucket wheel & elevator (Kone, Finland) relies on a little bucket wheel to gouge out the cargo before depositing it onto the bucket elevator to get it out of the hold. It has good reach but requires a large counterweight which in turn needs a more robust jetty. I think one was built & it was yellow.

Vertical srew conveyor machinery is yet another Scandinavian gadget affectionately referred to as a Siwertel. It does a clean job. Some don't like it but they are unfair & the machine has a lot to offer. I hope they're prospering.

Real En masse unloaders are an unknown quantity to me. Perhaps others will be able to illuminate.

Hope it helps. ■

For the use of en-masse elevators for ship unloaders refer to the following link.

http://www.buhlergroup.com/32780EN.htm?grp=60

For en-masse machines in general check out

http://www.buhlergroup.com

http://www.redler.com

and Google "en-masse" or "en masse" ■

Lump size is one of the main considerations. Some chain bucket type jobs & screws might/would easily choke on bigger lumps.

The are plenty of continuous machines handling coal & ores. Better ones are chain bucket & there was a Japanese machine which had a folding chain track & appeared able to dig out under the hatch coaming (is this the right spelling yet?). Some more ambitious devices (Simon Carves' Simporter) used pressed belts to lift material out of the hold. The belt feeding/collector was subject to a lot of wear. I haven't heard of either for many a long year. Which brings us nicely to the other main consideration. Abrasion levels should be inversely proportional to machine complexity. Remember where you heard it.

There is no such thing as a continouos unloader when rain, wind & repositioning are taken into consideration.

Grabs are quite handy & since I left the business I've come to appreciate their flexibility, reliability & low cost. Some sunny day someone will decide to develop a covered grab with an on board dust collector. It might be tricky; but worth the effort since most places already have capable cranes. There should be PhD's in it for any bright young things who know their way around CFD. Any takers?

Regarding classification, come on, this is bulk handling where anything goes. F'rinstance; Izaharis keeps pushing capsule transport & others keep knocking it back. Observing the alarming growth in machine complexity over recent years I fail to recognise the drawbacks of a capsule system. Tunneling strike rate is at least 10m/hour through good ground; Don't interrupt; I worked on the back up train for the Channel Tunnel; no support structure but some seepage pumping; a couple of tracks or similar against the idler hoops seen on tube belt runs across Asia; they must use them because they think they are clever; doesn't matter which. Throw in the cost of a 25 ply condom several kilometers long & then tell me there isn't room for alternatives. Anything should go. Glad I got that off my chest I can tell you. ■

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That's a nice looking grab. ■