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Hoist Types and Configurations

©Dr. B. C. Paul 1999

With Credit to Dr. H. Sevim for Original Book

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Major Components of Hoisting System Shaft - a near vertical hole in ground through

which things can be raised and lowered Head-frame - Steel structure over hole used for

lining up conveyance and directing cables Conveyance - That container for batch

movement of cargo - name varies with application

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Support Features for Conveyance

Since Hoist is a batch movement process needs loading and unloading features

Shaft features a loading pocket for material transfer quickly to conveyance

Usually a surge bin or ore pass to hold ore and smooth surges in production with need to keep hoist running steadily

Headframe usually has dump pocket to side to quickly catch discharge from conveyance

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Rope Handling Features

Conveyance moved by ropes or cables Headframe has rope handling and aligning

facilities Often have a large Sheath or Wheel at top

that redirects the cable May be a storage drum for rope to one side or

sometimes at top of headframe May have hoist house on top of frame

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Typical Hoisting System

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Two Major Types of Shafts

Inclined Shaft• Not Common today• Steeper than decline• In the wall haulage systems in open pits• May follow vein in small scale metal mine to limit

development to vein Vertical Shaft

• Boring Technologies up to medium sized• Large still need conventional sinking

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Uses for Hoisting Systems

Man Cages - Haul men and supply Utility Hoists - Mostly for supply handling Emergency Hoists - often in small shaft to

get few people out in emergency Production Hoists

• Will be focus of this unit• Used for removing pay product

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Application Hoist Influences what is raised and lowered When men and supplies are handled usually

called a cage• some may be multi-level

Production Handling - Called Skips Skips need way to get material in and out

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Skip Configurations

Solid and open at top• need special equipment to dump

Open at top - bottom opens• still need to be unload without dumping load

down the shaft

Side discharge - high production• open off to side of top• side opens for easy discharge to dumping pocket

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Types of Hoists

Drum Hoist• rope is stored on drum

Keope Hoist• rope just passes over wheel at top of headframe• must have a balancing load on other side• rope just sits over wheel and is held by friction• obviously some limits on how hard can

accelerate this

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Drum Hoist Configurations

Simple Single Drum Hoist• drum with rope wrapped around it

Just lowers the skip to anyplace in range of rope Inherently out of balance - big load down shaft

when at extension Out balance makes slow and suitable for only

limited depth Easily serves multiple levels

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Hoist Rope Drive Assemblies

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Drum Hoist Configurations Double Drum Hoist

• Two ropes wound in opposite directions

• Stick a load on each rope

• Creates a balance load - lower something when pulling something up - less energy and strain - can hit greater depth

May put a counter weight on one side - can then go to any level

May put two skips in balance - but now can only serve one level and expect skips to line up right.

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Drum Hoist Arrangements Double Drum with separated drums - one

clutched Functions like double drum except that now

can shorten one rope to allow multilevel service• Usually won’t do unless need to have two in

balance skips

Splitting drum and adding clutch increase inertia and cost

Runs short distances out of balance

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Drum Hoist Types

Double Drum Divided Both Sides Clutched Adding still more inertia and cost Can adjust for multi-level hoisting but

could do that with just one drum clutched Usually done for man hoists - need to be

sure that something will be able to run if it has to

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Weird and Wonderful Drum Tricks Simple drum is a cylinder

• problem is want to start hard - but theres lot of inertia and tremendous torc

Conical Drum• leverage to spin up to speed• Size can get scary fast

Cylindro-Conical• cylinder for starting rope - then flatten out to cone

Bycylindro-Conical• often creep away from load pocket and then hit it

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Keope (or Friction) Hoist Has to hoist in balance Control on inertia

• No large rope storage drums• No rope wrapped around everything

Generally less costly Not as Quick as Drum - can’t peel out the friction on

the wheel Sometimes have to put extra tare load to keep the

balance How in the heck are we going to serve multiple levels?

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The Multilevel Problem for Keope Hoists If just one level don’t care Can do a skip and counter weight and serve

multi-levels• if your willing to cut your production in half

Can use multiple wheels• each wheel has a skip and counter weight• if two levels can try to skip pairs (not at all

common)

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Choosing Between Drum and Keope Limited depth favors Drum Hoists

• Rope Storage is less scarey• Peppy acceleration boosts production

Multi-level favors Drum Hoist (but Keope can play too)

Greater Depth favors Keope• below about 3,000 feet drums usually can’t compete• Keope can do well on very shallow too

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Rope Handling Comparisons Keope Hoist

• Often uses several ropes on one skip• The ropes bend in parallel so no differential twisting• Multi-rope helps explain greater service depth• Multi-rope gives more friction surface area

Drum Hoist• has to be single rope to avoid pile-up and

differential bending• ever increasing rope size forces ever large drum to

avoid hard twist on rope

The Mystery of the Tail Rope

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Why would I leave a rope hanging downA shaft?

Wire rope is very heavy and can be a bigPart of the load.

Consider a Keope Hoist

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Balanced loads on each side are important to prevent slidingOver the sheave wheel.

What is out of balance here? The load in one of the scoops A big length of rope

Now What is Out of Balance?

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The load in one of the skips

Even though drum hoists don’t have the slipping issueThe unbalanced load is what the hoist motor has to workAgainst – unbalance is bad here too.