Easy-Lift Extension Ladder

By Martin Schmidt
Category: Tools, Workshop
Time Required: 15 to 30 minutes
Difficulty: Easy

For me, a big drawback of extension ladders is that it usually takes a lot of effort to extend them to the desired height. This is partly due to the way in which they are rigged. Typically, the ladder is operated by a rope which is fastened to the bottom of the extending part of the ladder. The rope runs through a pulley at the top of the stationary part and back down to ground level for the operator to grasp. This simple arrangement is inexpensive to manufacture but it requires a force on the rope which is equal to the weight of the moving portion of the ladder. If the ladder is large, or if the moving parts have a high degree of friction, the ladder can be very difficult to extend when it is standing upright. This, in turn, makes it difficult to control the ladder and compromises safety.

I recently obtained an old extension ladder for free. Its rope was missing and while I was measuring it to find out how much rope I needed to buy it occurred to me that I could convert the ladder to a double-pulley system which would make it easier and safer to use.

Steps

Step #1: Analyzing the mechanism

In the stock extension ladder, the single pulley simply translates motion from one direction to another. The force required to extend the ladder is equal to the weight of the ladder's moving portion.
In a double-pulley system, additional motion is traded to gain force. The rope needs to be pulled twice as far, but the force required is equal to only half of the weight being lifted.
The second pulley will be installed at the bottom of the moving portion of the ladder. One end of the rope will then be fastened to the top of the stationary portion. The rope will run down the ladder and through the new pulley at the bottom of the moving portion, back up and through the original pulley at the top of the stationary portion and then down to the operator at ground level.

Conclusion

The rope on a stock extension ladder is often polypropylene or something similar. It is tough but not particularly flexible. I selected a woven nylon rope which is abrasion-resistant and very supple.

After finishing the modification I stood the ladder upright and tested it. Extending the ladder was almost effortless. I've used it on numerous occasions since then and I'm very pleased with it.

2 Responses to Easy-Lift Extension Ladder

Martin Schmidt on November 30th, 2012 at 4:06 am said:

The ladder’s new rigging does not affect the catch lugs at all. They still operate exactly as they did before: Pull the rope to raise the ladder halfway from one rung to the next and the little guard pieces on the catch lugs swing into place to keep the catch lugs disengaged as the ladder is lowered.

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Martin Schmidt on January 17th, 2013 at 4:09 am said:

My ladder is on loan at the moment so I can’t measure it precisely for you, but if I remember correctly the pulley I used is closer to the 1″ x 3″ size that you mention. Try to get something that isn’t too large, or you may run into problems with the pulley hitting the rungs of the ladder as it is raised and lowered. Look at the ladder’s existing pulley and get one that’s about the same size. Make sure that both pulleys will accommodate the size of rope that you intend to use. Let me know how it turns out!

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