What Are the Advantages And Disadvantages of Hydraulic ...

What are hydraulic tools?

Hydraulic tools organically combine the hydraulic system with ordinary tools into a whole. Convert powerful hydraulic power into reciprocating linear motion, rotational motion, cycloidal motion and other mechanical motions. A complete hydraulic tool system consists of five parts, namely power components, actuating components, control components, auxiliary components and hydraulic oil.

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What tools are hydraulic tools?

1. Hydraulic wrench

Hydraulic torque wrench generally refers to a bolt-tightening tool that can output and set torque. It is a high-pressure hydraulic tool and is widely used in equipment maintenance and installation in many heavy and chemical industries. There are two types of hydraulic torque wrenches: drive shaft and hollow type.

2. Hydraulic wrench/tensioner/jack pump

Hydraulic wrench/tensioner/jack pumps include three types of pumps, namely wrench pumps, tensioning pumps and jack pumps. Their main function is to provide power for hydraulic wrenches, bolt tensioners, and hydraulic jacks. Each type of pump has subtle differences compared to other pumps, but their working principles are the same.

3. Hydraulic jacks

Hydraulic jack refers to a jack that uses a plunger or hydraulic cylinder as a rigid lifting member. It has the characteristics of compact structure, stable operation, large supporting force and self-locking. Hydraulic jacks have a strong support capacity, and heavy-duty hydraulic jacks have a support capacity of more than 100t.

4. Hydraulic bolt tensioner

The bolt hydraulic tensioner uses a hydraulic boost pump (ultra-high pressure hydraulic pump) to provide hydraulic power.

The tensile force is determined based on the tensile strength, yield coefficient and elongation of the material, and the tensile force generated by the ultra-high pressure oil pump is used to elongate the applied bolt in its elastic deformation zone.

The diameter of the bolt is slightly deformed, making the nut easy to loosen. In addition, it can also be used as a device for applying axial force to the hydraulic interference connection for top-pressure installation.

The biggest advantage of the tensioner is that multiple bolts can be tightened and disassembled at a fixed value at the same time with uniform force. It is a safe, efficient and fast tool and the best way to tighten and disassemble bolts of various specifications. It is used in the petrochemical industry, nuclear power, wind power, hydropower, thermal power, shipbuilding, railway, aerospace, mining, heavy machinery and other fields. According to different working conditions, application conditions and user requirements, special tensioners can be designed.

5. Hydraulic flange separator

Flange separator is a device for separating large industrial machines. It is divided into an integrated hydraulic flange separator and a split flange separator. Mainly used for pipeline maintenance, pipeline construction, testing and flange replacement, maintenance of gaskets, pressure vessels, cylinder head opening, power plants, bearing disassembly, oil and gas drilling, motor rotor disassembly, offshore platforms, jacking work, shipbuilding, industrial equipment, horizontal movement of workpieces and other industries.

6. Hydraulic nut splitter

Hydraulic nut splitters are used when the nuts on industrial equipment are exposed to the open air, high temperature, or corrosive environment, and are corroded and seized, and the threads are damaged due to collision.

Where the nut needs to be removed, it is usually very difficult to remove the rusted nut. The usual method is to use gas welding to cut off the nut and bolt together.

However, in some special working environments, electric welding is sometimes strictly prohibited, such as underground coal mines, pulverized coal bins of thermal power plants, oil pipes and high-pressure and high-temperature pipelines, etc., making it even more difficult to replace nuts and bolts.

7. Hydraulic puller

The hydraulic puller moves forward directly with the hydraulic starting rod, so the push rod itself does not rotate. The hook seat can directly adjust the distance forward and backward along with the thread. During operation, as long as the handle swings back and forth slightly, the hydraulic starting rod moves forward, the hook correspondingly retreats, and the pulled object is pulled out.

The hydraulic puller is easy to operate and labor-saving. The three-claw type and the two-claw type can be replaced according to the needs of on-site work. You can freely rotate and press the puller to move away from the center point of the piston, and quickly touch the center point of the workpiece being pulled. Optional pumps are available.

8. Other

In addition to the above common hydraulic tools, there are many other hydraulic tools. Such as hydraulic splitting machines, hydraulic presses, hydraulic punching machines, hydraulic pipe bender, hydraulic nut crushers, hydraulic clamps, hydraulic cutters, etc.

Advantages of hydraulic tools

1. Mineral oil is generally used as the working medium. The relative moving surfaces can be self-lubricated and have a long service life.
2. Light weight, small size, small movement inertia and fast response speed.
3. Various components of hydraulic transmission can be arranged conveniently and flexibly according to needs.
4. Overload protection can be automatically realized.
5. It is easy to operate and control and can achieve a wide range of step-less speed regulation (speed regulation range up to :1).
6. It is easy to achieve linear motion.
7. It is easy to realize the automation of the machine. When electro-hydraulic joint control is adopted, not only a higher degree of automatic control process can be achieved, but also remote control can be achieved.

Disadvantages of hydraulic tools

1. It is prone to leakage. The oil pressure of the hydraulic system is high, and the hydraulic oil can easily leak through seals or gaps, causing the consumption of hydraulic media and causing environmental pollution.
2. Low transmission efficiency: During the energy transmission process of hydraulic transmission, there are often more energy losses (pressure loss and flow loss, etc.), which makes the transmission efficiency low.
3. Inaccurate transmission ratio: Due to factors such as the compressibility of the transmission medium, leakage, and elastic deformation of the pipeline, the hydraulic system cannot strictly guarantee fixed-ratio transmission.
4. Sensitive to temperature. The viscosity of oil changes with temperature. Changes in viscosity cause changes in flow, leakage and resistance, which can easily lead to unstable movement of the working mechanism.
5. High manufacturing costs. To reduce leakage, hydraulic components require higher manufacturing precision, thus increasing manufacturing costs.

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At Last

Hydraulic jacks play a very important role in various large-scale engineering projects, such as building jacking, and it will be very effective to use together with a PLC synchronous jacking system. Therefore, TorcStark will introduce the common problems and solutions of hydraulic cylinders to you in detail to help you use it more easily.

(1) Why does the return speed of the hydraulic jack slow down?

The advantage of hydraulic jacks is that they are easy to operate, labor-saving and efficient. Its high efficiency is mainly reflected in one point, that is, the hydraulic transmission speed is fast, which ensures that the hydraulic jack has advantages unmatched by general mechanical jacks whether it is lifting or returning.

Of course, after a long period of use, the hydraulic jack is not as smooth as it used to be. With the increase of use time and frequency of use, some small problems will also occur with hydraulic jacks, such as the slow return speed of the jack, which naturally affects work efficiency.

The slow return of the hydraulic jack may be caused by the following reasons:

First, the state of hydraulic oil has changed under special circumstances. For example, extremely cold weather leads to an increase in the viscosity of hydraulic oil, which leads to a decrease in the fluidity of hydraulic oil, which naturally leads to the slow transmission of the entire hydraulic system, and the return speed of the hydraulic jack also decreases.

Second, there is a problem with the sealing ring of the hydraulic jack. Once the sealing ring is defective, it will lead to internal leakage or external leakage of the hydraulic jack, and the leakage of hydraulic oil will naturally seriously affect the transmission of the hydraulic system. When the transmission is stuck, the return speed of the jack will decrease.

Third, the return stroke of the hydraulic jack is by twisting the pressure relief valve, so that all the hydraulic oil in the main oil tank flows back to the oil storage tank. If the pressure relief valve is not fully opened, or even if there is a blockage of impurities, the hydraulic oil will not be able to flow back to the oil storage tank through the oil circuit smoothly.

Any occurrence of the above three points will seriously affect the return speed of the hydraulic jack, so everyone who uses the hydraulic jack must do maintenance work well, so that the hydraulic jack can work effectively for a long time.

(2) Is the hydraulic oil of the hydraulic jack universal?

The lifting principle of the hydraulic jack is the classic Pascal principle. By increasing the pressure and increasing the contact surface of the piston, the pressure of the large piston is doubled, and then the heavy object is lifted. In the whole hydraulic system, hydraulic oil plays a very key role, and it is the key to the transmission force. The hydraulic oil will show different states under different environments and temperatures, and the different states of the hydraulic oil will directly affect the performance of the hydraulic jack.

The lifting effect of the hydraulic jack will also be different due to the different types of hydraulic oil, so hydraulic oil is not a casual choice. When we choose a hydraulic jack, there will be a clear description of which hydraulic oil should be used for the hydraulic jack, that is, the original hydraulic oil from the original factory is more suitable. If a different type of hydraulic oil is replaced, there may be a series of poor operations such as insufficient pressure and slow lifting speed. This situation is mainly caused by differences in the pressure value, viscosity level and transferability of different hydraulic oils, which will have a huge impact on hydraulic jacks.

(3) What is the effect of damaged sealing on hydraulic jacks?

Most of the mechanical equipment containing fluids needs to be sealed by a sealing ring to ensure the normal operation of the mechanical equipment. This sealing ring type sealing design is the most typical in hydraulic equipment, especially hydraulic jacks, from which we can see the importance of sealing for hydraulic jacks.

Once the sealing ring of the hydraulic jack is damaged, its airtightness will naturally be seriously affected. Since the sealing ring is generally placed around the lifting sleeve, the hydraulic oil in the hydraulic system will no longer be 100% bound by the sealing ring. Under huge pressure, the hydraulic oil will overflow along the gap around the sleeve.

When the hydraulic oil overflows, the entire closed hydraulic oil circulation of the hydraulic jack will no longer be transmitted according to the normal route, resulting in a huge change in the internal pressure. As the number of uses increases, the amount of hydraulic oil will become less and less, which will eventually lead to the loss of the rated load of the hydraulic jack.

Therefore, in order to ensure the sealing of the hydraulic jack, we must always pay attention to whether there is hydraulic oil overflowing around the sleeve. If there is an overflow, then it must be stopped immediately and it must be inspected and repaired.

(4) Frequent use of hydraulic jacks can lead to &#;excessive fatigue&#;

Mechanical fatigue refers to the phenomenon in which materials, parts and components are locally permanently damaged at a certain point or at certain points under cyclic loading, and after a certain number of cycles, cracks are formed, or the cracks are further extended until they are completely broken. Overuse of hydraulic jacks can cause this problem.

If the hydraulic jack is used for a long time, the continuous and repeated lifting of heavy objects is prone to mechanical fatigue, resulting in the phenomenon of equipment friction and overheating, and the hydraulic oil will deteriorate after the temperature rises, and the lubrication and jacking capacity will be much worse than before. In this case, if you continue to use it, the accessories will be worn, and the gears, piston rods and sealing rings will be damaged. In severe cases, the equipment will be scrapped and cannot be used.

Therefore, after using the hydraulic cylinder for a long time, the operation should be stopped to ensure the heat dissipation and mechanical recovery of the hydraulic cylinder. The specific use time of the hydraulic jack depends on the brand and the different manufacturing materials, so you need to ask its manufacturer. Different hydraulic jacks have different limited usage times.

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