TESTING OF THE EXTENSION LADDER RESISTANCE TO SLIPPING WHEN SET UP ON A POOR SURFACE  

 

VS

 

TESTING OF THE EXTENSION LADDER RESISTANCE TO SLIPPING WHILE EMPLOYING THE SLIPSTOP STABILIZER WHEN SET UP ON A POOR SURFACE

 

      1. OBSERVATION​

Of the total number of extension ladder accidents, a large portion of these are the result of the bottom of the extension ladder slipping away from a structure.

 

Questions:

1. How much of the slippage of the extension ladder at the bottom can be lessened or eliminated by the attachment of the SlipStop Stabilizer?

2. Will the SlipStop Stabilizer work when using the extension ladder at various angles?

 

      2. HYPOTHESIS

With the addition of the SlipStop Stabilizer, the only way for the bottom of the extension ladder to move away from a structure horizontally would be for the ladder itself to be lifted off the ground, as all the weight would be on the legs of the SlipStop Stabilizer. Therefore, the more weight on the extension ladder, the more resistance the ladder would have against slippage when the SlipStop Stabilizer is employed. 

 

PREDICTED OUTCOME

Slippage of the ladder away from a structure at the bottom will be eliminated or greatly reduced with the addition of the SlipStop Stabilizer.

     

      3. METHOD

 a.) Measure the resistance to slippage at the bottom of the ladder without the SlipStop Stabilizer in place on an unstable lubricated plastic surface

 b.) Measure the resistance to slippage at the bottom of the ladder with the SlipStop Stabilizer installed on the extension ladder on the unstable lubricated plastic surface

 c.) Compare the findings from a.) and b.)
 

PHYSICAL METHOD

The SlipStop Stabilizer will be attached to the bottom of the ladder, adjusted to be off the ground by ¾” so that the ladder can fail when pulled (pic #1) , and the resistance measurement recorded.  The SlipStop Stabilizer will stop the ladder from falling and will now be resting on the ground.  A second pull will show the resistance created by the SlipStop Stabilizer and recorded.

 

      4. APPARATUS

a.) Structure to lean the extension ladder against

b.) Extension Ladder

c.) SlipStop Stabilizer  (pic #2)

d.)  A person on the extension ladder (Simulated by weights - 2 @ 35lbs, 2 @ 25lbs, one

10 lb chain for a total of 130lbs of weight)  (pic #3)

e.) Slippery membrane under the extension ladder feet  (pic #4)

f.) Slippery membrane on the floor to simulate poor ground conditions (pic #5)

g.) WD40 applied to the membrane to ensure poor bearing of the extension ladder to the

ground

h.) Scale to measure the resistance  (pic #6)

i.) Rope to pull horizontally from the bottom rung of the extension ladder  (pic #7)

j.) Rope at the top of the extension ladder to prevent complete possible collapse of

ladder (pic #8)

kj.) Sling to support the combined weights of 130lbs at 87” above the ground (pic #9)

       

       5. PROCEDURE  A

a.) Attach SlipStop Stabilizer to the extension ladder

b.)  Set-up extension ladder to a vertical height of 153” (3888) and a horizontal distance

of 38 ¼” (972) on the unstable surface consisting of plastic on plastic lubricated with

WD40.  This is the ladder slope of 4:1 or 14 degrees

c.) Adjust the SlipStop Stabilizer to be ¾” off the ground to demonstrate SlipStop Stabilizer NOT being engaged, and to allow for what the scale reading of the ladder fail will be WITHOUT the Slip Stop Stabilizer

d.)  Attach the sling to the ladder rung that is 87” (2210) off the ground

e.) Load sling with the 130lbs (simulating a person standing on a rung 87” up)

f.) Tie the top of the ladder to the structure (leaving some slack) to prevent total collapse when extension ladder slips at the bottom

g.) Attach scale to bottom rung of the extension ladder

h.) Attach the rope to the scale

i.) Pull the rope smoothly, horizontally, until ladder begins to slip away from the wall

j.) The extension ladder FAILED at a resistance of 4.2 lbs on the scale (see graph Pull #A1)

Pull #A2   6.4 lbs (see graph)

Pull #A3   5.7 lbs (see graph)

k.)  The SlipStop Stabilizer is now resting on the ground and engaged, having saved the ladder from continuing it’s fall to the ground

l.)  With SlipStop Stabilizer now fully engaged and resting on the ground, pull the rope attached to the scale smoothly, horizontally, until the ladder begins to move away from the wall 

m.)  Extension ladder DID NOT FAIL at a resistance of 41.4 lbs on the scale (see graph Pull #A11)

Pull #A22    43.3 lbs (see graph)

Pull #A33     47.1 lbs (see graph)

 

      5. PROCEDURE B

a.) Attach SlipStop Stabilizer to the extension ladder

b.)  Set-up extension ladder to a vertical height of 148.5” (3772) and a horizontal distance of 49 1/2” (1257) on the unstable surface consisting of plastic on plastic lubricated with WD40.  This is the ladder slope of 3:1 or 18 degrees

c.) Adjust the SlipStop Stabilizer to be ¾” off the ground to demonstrate SlipStop Stabilizer NOT being engaged and to allow for what the scale reading of the ladder fail will be WITHOUT the SlipStop Stabilizer

d.)  Attach the sling to the ladder rung that is 87” (2210) off the ground

e.) Load sling with the 130lbs (simulating a person standing on a rung 87” up)

f.) Tie the top of the ladder to the structure (leaving some slack) to prevent total collapse when extension ladder slips at the bottom

g.) Attach scale to bottom rung of the extension ladder

h.) Attach the rope to the scale

i.) Pull the rope smoothly, horizontally, until ladder begins to slip away from the wall

j.) The extension ladder FAILED at a resistance of 8.8 lbs on the scale (see graph Pull #B1)

Pull #B2   6.7 lbs (see graph)

Pull #B3   7..5 lbs (see graph)

k.)  The SlipStop Stabilizer is now resting on the ground and engaged, having saved the ladder from continuing it’s fall to the ground

l.)  With SlipStop Stabilizer now fully engaged and resting on the ground, pull the rope attached to the scale smoothly, horizontally, until the ladder begins to move away from the wall 

m.)  Extension ladder DID NOT FAIL at a resistance of 47.9 lbs on the scale (see graph Pull #B11)

Pull #B22    53.3 lbs (see graph)

Pull #B33     57.2 lbs (see graph)

 

      5. PROCEDURE C

a.) Attach SlipStop Stabilizer to the extension ladder

b.)  Set-up extension ladder to a vertical height of 145 (3683) and a horizontal distance

of 58 1/2” (1486) on the unstable surface consisting of plastic on plastic lubricated with

WD40.  This is the ladder slope of 2.5:1 or 22 degrees

c.) Adjust the SlipStop Stabilizer to be ¾” off the ground to demonstrate SlipStop Stabilizer NOT being engaged and to allow for what the scale reading of the ladder fail will be WITHOUT the SlipStop Stabilizer

d.)  Attach the sling to the ladder rung that is 87” (2210) off the ground

e.) Load sling with the 130lbs (simulating a person standing on a rung 87” up)

f.) Tie the top of the ladder to the structure (leaving some slack) to prevent total collapse when extension ladder slips at the bottom

g.) Attach scale to bottom rung of the extension ladder

h.) Attach the rope to the scale

i.) Pull the rope smoothly, horizontally, until ladder begins to slip away from the wall

j.) The extension ladder FAILED at a resistance of 2.2 lbs on the scale (see graph Pull #C1)

Pull #C2   3.1 lbs (see graph)

Pull #C3   5.2 lbs (see graph)

k.)  The SlipStop Stabilizer is now resting on the ground and engaged, having saved the ladder from continuing it’s fall to the ground

l.)  With SlipStop Stabilizer now fully engaged and resting on the ground, pull the rope attached to the scale smoothly, horizontally, the until ladder begins to move away from the wall 

m.)  Extension ladder DID NOT FAIL at a resistance of 45.2lbs on the scale (see graph Pull #C11)

Pull #C22    47.7 lbs (see graph)

Pull #C33     58.1 lbs (see graph)

 

      6. RESULTS

a.)  In all of the results of the Procedures A, B, and C, pulls A1, A2, A3, B1, B2, B3,C1, C2, and C3 using just the extension ladder, the slippage occured between 2.2 and 8.8 lbs.

 

b.)  In all of the results of the Procedures A, B, and  C, pulls A11,A22,A33, B11, B22, B33, C11, C22, C33 employing the SlipStop Stabilizer on the extension ladder, the slippage occurred between 43.3 and 58.1 lbs.  The ladder with the SlipStop Stabilizer attached did NOT slip at all three angles tested. 

 

SEE GRAPH FOR RESULTS

 

NOTE:  The more weight on the extension ladder (eg: a person over the 130lb testing weight) the more difficult it will be to drag the ladder away from the wall while employing the SlipStop Stabilizer on the extension ladder