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flintgreasewood

Hoist Brake System

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I'm trying to design a simple, yet effective, hoist emergency brake system.  One major consideration is that the bucket being hoisted does not stop at the top of the shaft.  It continues on up an incline to a dump point and then returns [see Fairbanks self dumping bucket ]  I've not been able to determine if the old Fairbanks system had a "down the shaft" brake, but I don't believe they did.  I'm sure these days MSHA would require it. If anyone has any good ideas please let me know.  I have the idea that an accelerometer could be used to activate a brake, but that gets into some pretty complex electromechanical stuff that I know very little about.

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Kurt,

 

Commercial (MSHA inspected) mines that operate using a hoist in a vertical or near vertical shaft have a dedicated hoist operator. The hoist has a drum brake. The brake is tested on regular intervals and the brake lining is inspected. Usually, the brake is composed of asbestos or equivalent high temperature lining that has the required braking qualities. It is lined on a circular band that clamps against the outside circumference of the drum in order to obtain the largest possible surface area.

 

There are probably standards and specifications for stopping distance with specified bucket loads.

 

The mine operator is as always responsible for having adequate braking for a hoist.

 

So, first of all, your hoist should already have a brake, if it was designed for vertical lift.

 

Cable brakes are (almost) impossible to design or develop. The issue is the amount of braking surface and where the brake would be installed. It isn't too hard to come up with a cable brake that binds the cable if it is relaxed. The issues with that are related to the "automatic" brake applying its-self when the bucket is rested and the cable tension relaxed. i.e you have two problems related to every solution.

 

What I have seen in mine shafts are doors that are hinged at the top. The doors are raised as the bucket moves upward and close as the bucket passes. Depending on the depth, there may be several safety doors. The hoist operator opens (raises)  the doors in succession as the bucket is lowered.

 

The best assurance of safe operation of a hoist system is frequent inspection and maintenance of cable, draw works and attachments. Properly designed safety doors will stop a free-fall bucket in the event of a failure of the hoist. More safety doors = more construction = more work = safer mine. :)

 

- Geowizard

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I think the best small-scale hoist brake system should require the brake to be ON always.  Impossible to move until operator manually releases it.

 

A buddy of mine built his brake system utilizing motorcycle front wheel brakes.  The newest innovations are dual disc, hydraulic, and NO electronic dependency.  This way, operator error should be the only question.

 

BTW, the same guy picked up a salvaged late model bike that was totaled.  The engine, gearbox, clutch are used for the lift.  Not exactly MSHA compliant but effective.

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Chuck,

   I like the safety door idea.  Since I'll not be very deep one door just above head height should do the trick.

Rod...brake always on could work going up but going down is problematic.  The only time a brake would be really important to have is when the bucket is being used to hoist and lower personnel.  All other times the hoist will be operated either from within the drift or from on top.

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I would have a 2 systems in case of a failure on one system, I like the using a disk bake setup attached to the drum from a car, truck. or motorcycle along with the safety door/s.

 

With a little ingenuity centrifugal force could be used to apply the disk brake system along with a lock out that would have to be either released manually or electrically to release the brake's hydraulics.

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