1. #1
    MembersZone Subscriber
    rmoore's Avatar
    Join Date
    Dec 1998
    Location
    Plano, Texas
    Posts
    815

    Default Inverted StepChock Prone to Failure?

    Well, here's one story I never thought I would be hearing. Review it and then let's hear what you thoughts are.

    Here's the original story from a North Carolina career Fire Captain;

    "I have a question for you. This is in regards to wood step cribbing chocks. Some instructors were sharing their opinion that inverting a step chock would cause catastrophic failure of the chock under load. I have personally never heard or seen that happening. Have you and if so, would you mind sharing?"

    This is something that I find not realistically possible so I wrote back saying I do not believe it would happen; especially at a simple vehicle rescue stabilization incident.

    What's your thoughts? How would you reply back to someone in your department who makes this type of statement?

    In June, I'm going to invert a step chock beneath a load of just about 38 tons so we'll see what happens.
    Ron Moore, Forum Moderator
    www.universityofextrication.com

  2. #2

  3. #3
    Let's talk fire trucks!
    BoxAlarm187's Avatar
    Join Date
    Jan 2003
    Location
    Virginia
    Posts
    3,326

    Default

    Ron,

    My first exposure to an inverted step chock was exactly 10 years ago in an advanced vehicle rescue class...seemed unusual at the time, but those of us who took the class brought it back to our home department, and it has been a regularly used method of stabilization for us.

    We've used it on every conceivable vehicle out there, and haven't had an issues or failures with it.
    Career Fire Captain
    Volunteer Chief Officer


    Never taking for granted that I'm privileged enough to have the greatest job in the world!

  4. #4
    Forum Member

    Join Date
    Nov 2002
    Posts
    1,182

    Default

    The only concieveable problem I can see with an inverted chock is a vehicle sliding off of it if there are slick surfaces, or perhaps flipping on it's side if the vehicle were to rotate because it was not chocked or cribbed in other places. I can't see it structurally failing in normal use.

  5. #5
    Forum Member

    Join Date
    Nov 2013
    Posts
    6

    Default Inverted StepChock Prone to Failure?

    I have never heard of something like that happening, I'd be interested to hear the result of your test.
    However, In any case an inverted step chock shouldn't be bearing too much weight as it is used to brace the vehicle to prevent movement.

    In the vehicle on roof scenario the car is already tipped forward with the weight of the vehicle taken by the bonnet (hood) and A-pillar, the inverted step chock will only bear any force when weight is shifted in the vehicle (such as firefighters/paramedics gaining access from the rear and crawling on the roof). That force would be negligible compared to the strength of the chock. It is there to prevent movement backwards only.

    Using the inverted step chock on an upright vehicle you are bracing the vehicle against other chocks or stabilisation equipment and not taking the weight of the vehicle. It is a different scenario to using cribbing or an "upright" step chock to hold the weight of the vehicle (flat tyre blocking etc.
    Due to the angle that the inverted step chocks presents against the vehicle it would be inappropriate to use it for load bearing cribbing.

    Personally, for a vehicle on its wheels I try to use the step chock upright in the first instance and brace it with a thin wedge as the increased surface contact with ground and vehicle reduces the risk of the chock slipping. However in many cases the height of the vehicle sill doesn't line up close enough with a step on the chock so quickly inverting it provides the next best option for fast and effective stabilisation.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. How Do You Build the Simple StepChock?
    By rmoore in forum University of Extrication
    Replies: 4
    Last Post: 12-29-2010, 11:17 PM
  2. The Inverted 'V' Chevron Pattern
    By rmoore in forum University of Extrication
    Replies: 7
    Last Post: 02-22-2004, 07:39 PM
  3. Inverted Mini-van Pt Extrication
    By MalahatTwo7 in forum University of Extrication
    Replies: 9
    Last Post: 05-20-2002, 01:32 AM
  4. Accident prone? Tell your story...
    By Fireguy57 in forum Fire Explorer & Jr. Firefighting
    Replies: 3
    Last Post: 01-12-2001, 06:02 PM
  5. Inverted Step Chock Stabilization
    By rmoore in forum University of Extrication
    Replies: 6
    Last Post: 04-20-1999, 04:46 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Log in

Click here to log in or register