Polyspasty. Travel Tips

TOURIST ADVICE
Free library / Directory / Tourist tips

Polyspasty. Travel Tips

Tourist tips

Lotspast - a system of blocks and ropes, designed to lift heavy loads or pull ropes, using the principle of leverage in its work (we win in strength - we lose in distance). Blocks are rarely used directly in hikes (climbing), carabiners are more often used (they are more versatile) (not "IREMEL" !!! Dural "IREMEL" are quickly rubbed with loaded ropes and become unsuitable for further use). Friction on carabiners greatly reduces the gain in strength. To reduce friction at the turning points of the rope, two carabiners (preferably of the same type) are placed. Putting three carabiners is useless: two carabiners will squeeze out the third one and everything will remain the same. (In all the figures, one carabiner is shown at the turning points of the rope).

In climbing, the chain hoist is used mainly in rescue practice, or in pulling ropes when organizing crossings.

On fig. 40 shows the so-called "long loop". This is the simplest pulley. One end of the rope (root) is attached to the relief, the middle of the rope is fastened into a carabiner attached to the "cargo" so that it can freely slide through the carabiner. For the second (working) end, the rope is pulled. In this scheme, half the weight of the "load" is on the anchor point of the rope, and the other half is on those who pull the rope. In rescue work, this scheme is usually used to lift a lightly injured person. If the rescuers accidentally release the working end of the rope, the victim will fall down. To prevent this from happening, the working end of the rope must be secured with a grasping knot (not shown in Fig. 40). The same scheme is often used as a belay system for a grasping knot in carabiner brake.

Fig. 40.

On fig. 41 shows the chain hoist itself.

Fig. 41

In space, the letter “z” is “written out” with a rope: the rope from the “cargo” goes to the attachment point of the chain hoist, there it unfolds in the reversal block (carbine), returns to the “cargo”, unfolds on its block or carbine, goes to the attachment point of the chain hoist, where and is stretched by pullers. In this scheme, 3/4 of the weight of the "load" falls on the attachment point of the chain hoist (load point) and only 1/4 of the weight falls on the pullers. (Friction on the carabiners, and even more so on the terrain, as shown in Fig. 42, significantly reduces this gain in strength).

Fig. 42

If the pullers let go of the rope, it will slip through the blocks and the "load" will fall again. To prevent this from happening, between the "load" and the attachment point of the chain hoist on the cargo rope, a grasping knot is knitted, which is fixed either directly on the attachment point of the chain hoist, or at a separate point (in Fig. 42-43 the grasping knot is fixed at a separate point). This grasping knot will be called the holding grasping knot, or simply the holding knot. When the rope is pulled out, the knot holding the knot carried by the rope will be pulled into the reversal block (carabiner), so it must be regularly displaced from the block.

Fig. 43

The length of the ropes used in modern climbing rarely exceeds 50 meters. As can be seen from fig. 41 rope passes three times between the "load" and the attachment point of the chain hoist. That. the maximum lifting depth is only 16 meters, which is clearly not enough in large mountains.

It is possible to increase the lifting depth if the second turn of the rope is organized not on the “load” itself, but on the second grasping knot located between the “load” and the holding one (Fig. 42). This grasping knot will be called a pulling grasping knot, or simply a pulling knot. The rope is selected until the puller approaches the holder. The rope is gradually released. The load will move to the holding one, the pulling one will weaken. It is dismissed and shifted to the "cargo". Again begin to choose the rope. The load passes to the pulling one, the holding one weakens, it is dissolved and they begin to be displaced from the block so that it does not become pulled into the block.

It is more convenient to work, faster to assemble, and has a number of other advantages, a scheme in which the gripping units are replaced by mechanical clamps. But a mechanical clamp cannot be a means of insurance. Therefore, during rescue operations, while lifting the victim, only the pulling one is replaced with a mechanical clamp, for example, a jumar (Fig. 43). When installing a hinged crossing, where there is no person on the tensioned ropes, both grasping ones can be replaced with mechanical clamps.

Authors: Rastorguev M.V., Sitnikova S.A.

We recommend interesting articles Section Tourist tips:

▪ Prime Meridian

▪ camel knot

▪ Grasping knot

See other articles Section Tourist tips.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Lithium-sulfur batteries for electric vehicles 02.12.2013

Employees of the Lawrence Berkeley National Laboratory (USA) have created a laboratory prototype of a lithium-sulfur battery (Li-S), which has twice the energy density compared to lithium-ion batteries.

The new battery provides more than 1500 charge-discharge cycles with minimal capacity loss. This is the longest life cycle for this type of battery to date. The demand for high-capacity batteries for hybrid and all-electric vehicles is driving scientists to look for new types of batteries that could provide vehicles with a longer range than today's popular lithium-ion batteries.

In order for an electric car to be able to cover at least 450 km on a single charge, the specific energy produced by the battery must be from 350 to 400 W h / kg. However, modern lithium-ion batteries provide only half of this energy. Another important requirement: batteries must provide about 1000-1500 charge-discharge cycles without significant power loss.

Prototypes of batteries created in the laboratory. Lawrence, potentially provide the possibility of creating electric vehicles with a range equivalent to the range of cars with gasoline units. At the same time, electric vehicles are fundamentally different in that they have zero emissions. Under laboratory conditions, the lithium-sulfur battery generated more than 500 Wh/kg during the initial testing phase and provided energy production of the order of 300 Wh/kg after passing 1000 charge/discharge cycles.

Currently, the development team is looking for support to continue the work on the improvement of lithium-sulfur batteries. Scientists also need to solve the issues of more complete utilization of sulfur, issues of extreme operation of batteries, etc.

Other interesting news:

▪ 32/64-bit processor from Intel

▪ LED in oil

▪ Internet addiction is hidden in the genes

▪ Energy from paper

▪ Hybrid electric boost

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Application of microcircuits. Article selection

▪ article Pathological anatomy. Lecture notes

▪ article Who is a Mormon? Detailed answer

▪ article by Cleome the bird-legged. Legends, cultivation, methods of application

▪ article Electric pumps. Encyclopedia of radio electronics and electrical engineering

▪ article Electric machine rooms. Scope, definitions. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews