1. #1
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    Default Aerial Ladder Jack Plate Cribbing

    I'm looking for information regarding cribbing aerial ladder jack plates. Obviously, the reason for cribbing is to spread the transfer weight of the ladder while operating on soft ground, but does anyone know what constitutes recommended cribbing? Several points:

    - NFPA requires max PSI per ground pad of 75 psi, the cribbing reduces this.
    - I've been researching this and cannot find anything in NFPA standards or IFSTA training material. I remember from long ago somone was recommending wood, but can't find anything that describes what size and type of wood.
    - I've seen 4x6" boards to 3/4" plywood, again no formal body that I can find says anything other than its up to the operator to ensure the aerial is being operated on ground strong enough to support operations.
    - I'm looking for the science behind your recommendation or practice.

    Thanks in advance. Any information or thoughts are greatly appreciated!
    John E. Burruss, NREMT-P
    Heavy-Technical Rescue Instructor
    Virginia Department of Fire Programs

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    Contact the manufacturer of your aerial. They would likely be able to point you in the direction of NFPA standards for obscure things like that.

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    Didn't the ladder come with ground pads? Footrat has your starting point. 3/4" plywood is NOT going to do it, I'd say the plywood would have to be at least 2" to start with. You can make good plywood pads by building up layers with a good quality adhesive and marine grade plywood.

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    I have been a Truck Co. firefighter since 1991, and a driver/operator of aerials since 1995, never heard of, seen or otherwise anything else regarding wooden cribbing or even wooden plates??? Every Truck Co I have operated (lemme see if I can remember em all- 1976 Mack/Thibault 100' Rearmount, 1994 Pierce 65' Telesqurt, 1979 Maxim 100' Rearmount, (3) Pierce 100' quints) had aluminum or steel plates. Even took the MFRI Aerial D/O class with the accompanying IFSAC/Pro-Board Aerial/DO test and never heard of it.........Am I missing something here????
    Last edited by FWDbuff; 01-24-2012 at 06:18 PM.
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    Lest we forget this thread from last year...just food for thought.
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    Thoughts...

    Already contacted Pierce, they have no recommendation for enlarging the ground pad and there is no NFPA or OSHA standard that covers this.

    Yes, our ladder came with ground pads. We are looking for using the aerial on soft ground as a last resort and obviously need to increase the ground pad dim by using cribbing.

    Our state agency used to teach usng cribbing as part of the aerial operator curriculum back in the 80's. I wish I had the notes and can't find anything that references this.

    Thanks to all for the pics and ref to the thread. I did get a lot of useful info and the pics are real eye openers!

    The only place I've had success getting info is the towing industry. They have done extensive research on cribbing because rotator wreckers really load their stabilziers. Once I finish this research project, I'll post results.

    I'm surprised this is raising a commotion... I've been an aerial operator for +30 years and cribbing is nothing new to me... just need solid data because we now have a need to carry some.

    Thanks to all... keep the thoughts coming!
    John E. Burruss, NREMT-P
    Heavy-Technical Rescue Instructor
    Virginia Department of Fire Programs

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    John,

    Having worked in the central part of the Commonwealth with at one time 9 first line truck companies, we tried our very best to shy away from placing an aerial truck on soft ground. The first thing to consider is the weight of the ride and how much is going to be placed on each jack or outrigger. That being said, the RFD only used steel plates. I can't remember only a few instances where we did actually placed a truck off the hard surface and that was on ground which was frozen.

    A minimum of 4x6's should work if they are 24 to 36 inches square or even larger

    I'd like to know what you do find out to resolve this problem. It would be interesting to see and allow others in this site to learn from another Virginian!
    Stay Safe and Well Out There....

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    Cribbing as an option to enlarge the footprint of the pads isn't something new too me either. It's been talked about and shown many times during my career. I've never specifically done it, but wouldn't be opposed to a short crib. I have worked side by side with house movers and am confident that a properly cribbed aerial would have no issue with down-force, my concern would be shifting due to rotation, again short-fat would be better than narrow tall. I look forward to seeing what you find with the towing industry and any actual literature or data.

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    Reading the original post, it sounds like you are more concerned with spreading your weight rather then increasing your jack height.

    You should contact a local Professional Engineer and explain what you are trying to do. I work in H&S and am well versed in OSHA.

    I will tell you for loading of lumber, 3x10 rough-cut lumber is used to crib cranes, as well as used in solider piles, and earth retention. I have used 3x10s to matte 275ton crane.

    I have been trying to find load calcs for rough cut, I am coming up empty handed. I will email one of my PEs and see if can get further info.

    My previous company, I believe the plates for the riggers were 24x24, I would at least suggest 4 times 3 x 10 rough cut timers, 40" long. that would give you a 40 by 40 pad.

    If the previous post was about 75 psi, on a 24x24 plate, and you take that plate and set it on top of 40x40 pad. That would reduce your total psi form 75 to 27, much more unlikely to sink pushing 27psi.

    As a previous post mention short and fat... 3x10s would most likeyly be the best for this application. a Professional Engineer could run a few calcs, and give you a stamped letter. Having the engineer calc this and stamp it would add to the insurance of the safety.

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    Try to strictly adhere to the manufacturers SOP for the equipment. I regularly work with a KME quint. This tower has a road weight of 79,500 lbs, and is fully suspended upon the out riggers when operating. KME wants the set-up to be made 100% of the time on hard surfaces. It is not recommended to be placed anywhere that outriggers will be in contact with sidewalks or dirt/lawn surfaces. We do operate on the drill ground where I know the roadway support is 6 feet of sandstone/shale and compacted.

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    Smile

    We use 3"x10" lumber cribbing sometimes when setting up our 75' Aerialscope on a curb area covered with lawn or a long side a driveway which maybe on a slope or on gravel. When setting up on blacktop we use the steel plates that came with the apparatus !
    Last edited by Woodbridge; 08-10-2013 at 09:36 PM.

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