What is a ladder and how do I choose a ladder?
What are ladders and ladders? Ladders are props that allow people to ascend to work, such as repairing lights, wiping glass, etc. All these things require a ladder.
You have to learn how to properly ladder and purchase ladders that suit you.
Before using the ladder properly, we must understand the four general attributes of the ladder: form, height, load bearing and material and how they affect you.
1. Form
I wonder if you have noticed that no matter what kind of ladder it is, its width is almost the same, almost as wide as your shoulders. No matter how the ladder structure is designed, the final work has two forms:
One is a straight ladder and the other is an A-shaped ladder.
Let's focus our attention on the straight ladder.
Vertical ladders require a set of support points to work up and down separately. Needless to say, below is the ground. The upper part needs to be supported by a wall, such as a gutter.
When setting up a straight ladder, common sense tells us that we can't place it vertically, it will fall down.
The safety angle for installing the vertical ladder is:
The vertical angle is 15, that is, the horizontal angle is 75.
The principle is about 4:1, the ladder rises 4 feet, and the ground is 1 foot outward. Please note that 4 feet is the vertical height here, and the ladder is on the inclined edge, which is actually slightly longer than 4 feet.
If you think this method is not easy to master, you can use this simple technique: stand straight and lean your feet on the ladder. If your arm is straight, you can directly touch the ladder, this angle is correct. If the arm bends when the hand touches the ladder, the ladder frame is too straight.
The ground on which the ladder is to be erected must be level, otherwise the ladder will be slanted and cannot stand. You don’t think that when people go up, the center of gravity moves upward and collapses easily. Try to pick a flat ground, set up a ladder, or use something to cushion one foot of the ladder.
The ladder feet should be fixed correctly, and it is best to support the ladder feet with heavy objects.
When climbing a ladder, you should pay attention to your body and approach the ladder. Some people think they have been tied to the ladder. In fact, their hips are far away, and it is very dangerous to shift their center of gravity. Most people stick their abdomen on a ladder like rock climbing. If their legs are too long to crawl, some people will use their knees to crawl slightly to the side. In any case, keep your ass as close to the ladder as possible.
It is forbidden to climb from behind the ladder.
Don't stand two steps above the ladder. the reason is simple. If you have reached the first two parts, where should you put your hands?
Another type of ladder is the A-type ladder.
If the ceiling lamp in the house is broken, the vertical ladder cannot be erected, because the ceiling lamp is in the middle of the house, and there is no wall around it to stand. In this case, an A-shaped ladder will be used. The deployment of the A-type ladder is a fixed safety angle and can be directly installed on the ground.
The "A" ladder is relatively stable in the direction of the "A" bracket, but it is still easy to flip in the lateral direction, even easier than a straight ladder. Some people mistakenly believe that the A-type ladder is stable. In order to save trouble, they stood on the ladder and moved the ladder, causing an overturning accident.
Even if you find that many A-shaped ladders have flat tops, they cannot stand on top.
2. Height
If you want to climb the roof, that is to say, you are not satisfied with just standing on the ladder and temporarily leaving the ladder after climbing, then your ladder needs to be 3 feet or 1 meter higher than the eaves. The reason is that when you return to the ladder, you need to press and hold the ladder with your hand, otherwise there will be an embarrassment of not going up, remember.
Let's do a small exercise to see how long the ladder will take if you are going to climb the roof.
Suppose the eaves are 20 feet from the ground and the eaves are 1 foot from the wall. If we install the ladder on the eaves, according to the 4:1 principle, the safety distance from the foot of the ladder to the wall is 15 feet = 6 feet. The trigonometric function calculates that the right-angle sides are 5 feet and 20 feet, respectively. The hypotenuse of a right triangle, that is, the length of the ladder needs 20.6 feet, plus the extended 3 feet, it needs about 25 feet of ladder to reach the roof.
There is another sentence, when you go to the store to buy a ladder, you should clearly see the description of the height of the ladder. Is it the physical length of the ladder itself? Or is it the height at which one can climb the ladder? The two "heights" usually differ by 3 feet or more than 1 meter. The two heights of the ladder manufacturer can sometimes seriously mislead you.
The internal height of the house is about 8-10 feet. In most cases, a 6-foot A-shaped ladder can meet indoor needs. If you need to clean the fallen leaves in the gutter, you need a higher vertical ladder to hang colored lights on the eaves. The above-mentioned 25-foot-long ladder, even a 25-foot-long double telescopic ladder, is a large ladder. Please note that a 25-foot ladder has two parts, not only 25/2=12.5 feet high, but also a sufficiently long overlapping area between the two parts to ensure strength.
It is not safe to stand on a higher ladder. This is simple because the center of gravity is high, but the width of the ladder has not changed. Don't try the dangerous moves you often do on a 6-foot ladder or a 12-foot ladder! If conditions permit, ask another person to help you get the ladder. Only a little force is needed to stabilize the ladder, which can greatly reduce the occurrence of accidents.
3. Bearing
Load-bearing refers to all the weight on the ladder, including the sum of people and items carried by people. An experienced roofer will not climb too many tiles at once, even if he can move them.
Fourth, the material
At present, most ladders are made of aluminum or fiberglass, both of which are very light and have high strength. In most cases, you can choose one of them. However, if you are operating electricity, fiberglass is the first choice.
2020/06/29
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