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How many men would it take to raise a portcullis?

Discussion in 'Research' started by Butterfly, Jun 28, 2012.

  1. Butterfly

    Butterfly Auror

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    The particulars...

    The guys are outside trying to get in. The mechanisms (inside) are damaged and out of reach.

    The castle is abandoned so there is no threat to them being stabbed in the chest or impaled by enemy spears in the process.

    The gate in question in an average sized metal portcullis. Any idea how much they weigh? I'm thinking about 2,000 lbs, but I may be way off. (I have no idea on dimensions at this point).

    The fellas doing the lifting are all trained swordsmen, so in theory, stronger than your average male.

    I'm guessing, it will take about twenty to two dozen to raise it enough to allow a few inside to lock it open / repair the mechanism.

    Another question is, will they all fit in side by side to get enough hands on it?

    Advice appreciated...
     
  2. T.Allen.Smith

    T.Allen.Smith Staff Moderator

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    Let's say for the sake of simple math that the portcullis is a ton. 20 men pressing 100 pounds each seems more than reasonable if they could all stand evenly in that space, 15 men = 133 lbs, 10 = 200, and so on....

    I don't think your reader will be too concerned with this detail. For one thing, the weight between actual historical portcullis probably varied greatly depending on the size of the castle. I'd just pick the size & weight that works for yours and run with it.

    Another question that you should ask yourself though is if there's a locking mechanism. I believe most portcullis had some sort of lock. That,in addition to the weight would complicate the issue. However, if it's abandoned, maybe the lock wasn't engaged. I'm not sure if your looking for more obstacles in your story or less so figured I'd throw that out there.
     
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  3. In practical terms, if you've got 20 or 30 guys trying to get into an undefended castle, it might be simpler for them to just make a ladder and go over the wall, since nobody's trying to stop them. But the portcullis route is fine, especially if they only need to open it enough for one small guy to slither under it and use the winch or whatever. (Although you said the mechanisms are damaged; do they have to be damaged?)
     
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  4. Butterfly

    Butterfly Auror

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    I suppose not... good point.
     
  5. JonSnow

    JonSnow Troubadour

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    If I had to guess, I would say that a portcullis weighs a lot more than 2,000 pounds. Think about it... its a gigantic grate of wrought iron, probably 15 feet wide and at least that tall (I guess that would vary, depending on the castle), with the bars being 6 inches thick and solid.

    I would guess your "average" portcullis would weigh 8-10,000 pounds, if not more. So the average man, basically dead-lifting 150 pounds (which for warriors isn't very much), I would say you would need 60 men at least. If your men can lift 250 pounds each, which I still think is reasonable, you might be able to do it with 35 men.

    But with that many men, you start running into space problems, as they are going to need to stand side-by-side to lift. You can probably only fit 10 men in a 15-foot wide space... 20 if you get 10 on the other side of the grate.
     
    Last edited: Jun 28, 2012
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  6. Lavender

    Lavender Minstrel

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    Good question, as I have a portcullis in my story. How many people would it take to power the winch from the inside is what I would like to know if anyone would care to let me know :D
     
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  7. Lawfire

    Lawfire Sage

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    They could use a timber or log as a lever to pry that thing up. It would require less man power and gives more of a working area. If there is something they could move under once it was up, they would not have to hold it long.
     
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  8. SeverinR

    SeverinR Vala

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    I found a source that said the liberty bell weighs 2000 pounds.
    So a 10-20ft tall gate would weigh more then a bell.

    If it is locked, it will take alot more work. But someone climbing over and unlocking would change that.
    If the winch still works, they lift it enough to get someone in, or have someone climb over and simply open it.
     
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  9. Graylorne

    Graylorne Archmage

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    Silly question perhaps, but isn't there a sally-port? Would be a fine thing, all those men working themselves to death to raise the portcullis only to discover the side-door was open all the time...
     
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  10. Butterfly

    Butterfly Auror

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    Unfortunately, there's no sally port, and no grounding for ladders. The fortress in question is on a ravine side. I have decided to have a couple of guys climb a rope, do the necessary repairs, and open the blooming thing - although, dealing with the counterweight might be a problem... the drawbridge chains have been smashed.
     
  11. Zophos

    Zophos Minstrel

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    JonSnow was on the right track, but I think he's a bit underweight on the estimate.

    One inch (diameter) rebar weighs 2.67 lbs. per linear foot. Rebar is made of steel which has about the same density as wrought iron (490 lbs per cubic ft vs. 485 or so). A six inch diameter piece of rebar would weigh 96 lbs per linear foot.

    A 12.5 ft by 12.5 ft portcullis made of uniform material (six inch diameter rebar) would weigh almost 18,000 lbs. That's a construct with nominal 1 ft gaps between any two bars and of uniform construction.

    Depending on your period, it's unlikely that a piece of metal that size could be manufactured by standard processes. More common designs were metal rods slatted together or some grouping of reasonably sized (4 ft x 4 ft) tiled lattices slatted together in a similar fashion. Those types would cut your weight down considerably, but you're still talking about a structure that weighs upwards of 12,000 lbs. The mechanism used to open a portcullis was commonly a set of very large counterweights (sandbags or very small rocks ;)) linked to a system of pulleys (and later gears) to provide mechanical advantage to "several" men or a pack animal working a winch.

    That's all pure conjecture, but the math works out and the rest lines up with portcullis's I've seen.
     
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  12. Zophos

    Zophos Minstrel

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    Oh yeah, the how many dudes to lift it part...

    Assuming a 12 ft high portcullis, if each fellow could stand in a 2 ft space (which probably isn't possible for dudes big enough to do it) they'd need to deadlift somewhere between 2300 and 2800 lbs per man. The world record is something like a thousand pounds, so you're better off tossing a couple dwarfs over the other side to get busy on the winch and pulleys.
     
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  13. Steerpike

    Steerpike Felis amatus Moderator

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    Might I recommend Gotrek? Then you only need one dwarf :)
     
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  14. Zophos

    Zophos Minstrel

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    If that cat can deadlift 12-18k lbs, you may as well just say, "Gotrek, smash!" and follow him in.
     
  15. Steerpike

    Steerpike Felis amatus Moderator

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    True.

    Well, he probably couldn't pull it off alone, though in the Warhammer novels he manages some amazing feats. Maybe if he had Conan standing on one side of him, and Karsa Orlong (Malazan books) on the other.
     
  16. Zophos

    Zophos Minstrel

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    Somehow, I just know that this ties back to the number 42, somehow.

    I just know it does!
     
  17. Steerpike

    Steerpike Felis amatus Moderator

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    It does!

    Not to derail the thread further, but if you take the names Gotrek Gurnisson, Conan, and Karsa Orlong, assign 1 point for each consonant and 2 points for each vowel, then add them all up, you get:

    42.
     
  18. Zophos

    Zophos Minstrel

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    I knew it!

    Stumbled across this today when I was mucking about. Link
     
  19. Steerpike

    Steerpike Felis amatus Moderator

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    Good link, Zophos. I really like the Douglas Adams books.
     
  20. Stuart John Evison

    Stuart John Evison Minstrel

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    All the portcullis mechanisms I've seen here in England were always open but I do know they had dead man locks so with the chains smashed someone would have to scale the battlements to get to the winding room in the gatehouse and smash free the deadlocks. Then those on the ground could lever it up enough to prop it open with a baulk of timber, you'd never try to straight lift it unless you were in an urgent hurry and had more men then sense; those things are massive and built of English oak which weighs enough on its own let alone with the wrought iron reinforcing.
     
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