Hydraulic jacks differ from their mechanical counterparts primarily in the amount of physical effort applied by a person to perform the same work. So, when working with hydraulics, these efforts are many times less, even if their drive is powered by human muscular strength.
The capabilities of hydraulic jacks are strikingly different from the capabilities of both mechanical and pneumatic counterparts. Key Features:
- carrying capacity from 1.5 to 200 tons (in some cases - up to 1000 tons);
- high efficiency - close to 80%;
- small working force;
- smooth running;
- high structural rigidity.
The disadvantages of most hydraulic jacks include the initially large height of most devices and the need for maintenance during operation.
We will consider the device and principle of operation of a hydraulic jack using the example of their most common type - a bottle plunger hydraulic jack. They come in different lifting capacities -3t, 5t, 10t, etc.
Everything is quite simple: there is a piston in the cylinder and either in a separate reservoir or in the same cylinder above the piston there is hydraulic oil - the working fluid of the jack.
The hydraulic jack is actuated by a plunger - a small pump that pumps oil through the bypass valve into the cavity under the piston. Due to the difference in the diameters of the plunger and the cylinder of the jack, the applied force is minimized. The fluid pumped under the piston pushes it out, lifting the load above it.
Lowering the jack is done by slowly bleeding the hydraulic oil from under the piston into the top of the cylinder or reservoir.
This is the principle of operation of all hydraulic jacks.
Another thing is that not all of them are equipped with a plunger pump, and both a separate hand-held device connected to a jack and a hydraulic station can act as a plunger.
And now is the time to consider in more detail the types of hydraulic jacks, places and methods of their application.
Varieties of hydraulic jacks, their advantages and disadvantages
The first of these, the most common and well-known, are bottle-type jacks, they are often (according to the most classic application) called automobile hydraulic jacks.
Their line for most manufacturers starts from one and a half tons and reaches 15 - 20-ton modifications. They are simple in design, compact in laying and unpretentious in maintenance, they are able to faithfully serve a zealous car owner for many years.
Actually, maintenance, in most cases, comes down to checking the oil level, topping it up if necessary, and periodically idling the jack so that during operation all its parts can be lubricated, the springs work and the balls of the bypass valve turn, which will prevent them from sticking due to for rare use and will not lead to the inoperability of the device in a critical situation.
Just because of the possibility of oil leakage, it is better to store bottle hydraulic jacks in an upright position.
Repair of such jacks is extremely rare, but if the jack is worn out - for example, at a service station or in another production, then it most often comes down to replacing the piston and plunger cuffs, rubber seals, less often - springs and bypass valve balls.
Advantages of the hydraulic bottle jack:
- compactness;
- stability;
- durability;
- low applied force;
- versatility of use - in addition to vehicles, such jacks are used in construction, on railway transport, as a power unit for pipe benders and pipe cutters;
- ease of repair.
It is these jacks that are the main and practically uncontested on trucks.
Their disadvantages include:
- high initial height;
- low lift height
- inability to work in a non-vertical position.
Now automobile hydraulic jacks are produced in a convenient compact package, which makes their packing and storage in a car, especially on long trips, very convenient and neat, preventing damage to things carried in the luggage compartment by possible oil ingress.
By the way, the shape of the drawers and the location of the handles transparently hint at vertical storage bottle jacks. But rolling hydraulic jack it is devoid of these shortcomings, although it is both more expensive and less compact, but as a car jack it is not inferior to a bottle jack, and in some cases even surpasses it, in particular:
- when working on sites with a slope;
- has a significantly lower pickup height;
- easier to move and install under the car thanks to the wheels;
- has a higher lifting height (from 300 to 400 mm).
Another, in our opinion, interesting model car jack was created on the connection of two types of this device: rhombic screw and hydraulic. This is, of course, a hydraulic jack, but its force is transmitted with the help of levers to a rhombic lifting device, which has undeniable advantages:
- low pickup height;
- no deviations in vertical plane when lifting;
- high lifting height.
We will be wrong if we do not mention some of the less well-known, but no less useful representatives of hydraulic jacks.
Choosing a hydraulic jack for your purposes
In addition to purely automotive, or rather, predominantly automotive, there are other hydraulic jacks that not only push the piston, but also retract it.
Moreover, they can do this both on one side and on both sides. These, and similar ones, jacks are most actively used in body repair automobiles or similar industries.
They usually do not have their own plunger and are used with an external oil pump, either manual or electric.
The same external device is also needed for hydraulic jacks with stepped lifting height or with fixation with a nut.
These are specific jacks, more often used in production, but in the conditions of a car repair shop, occupied incl. repair of trucks, they can become indispensable assistants considering them:
- exceptional reliability and durability;
- high (significantly greater than that of bottle hydraulic jacks) load capacity;
- no need for additional fixation of the cargo;
- no need for human effort when lifting at all.
It remains in this section to mention one more, somewhat specific and not particularly familiar to most users, the type of hydraulic jack - a hydropneumatic jack.
Actually, it often also has a plunger for purely mechanical work, but it is also equipped with pneumatic drive for pumping oil. It is convenient to use it either in a garage equipped with a compressor, or on a car equipped with the same device.
In addition, our Chinese friends already offer an attachment to a conventional bottle hydraulic jack, which turns it into a hydropneumatic one.
As you can see, both the scope of hydraulic jacks and the choice of options for their execution are more than wide. Therefore, finally, about one of the most common homemade products using a hydraulic jack - the press.
Technically simple and easy to use self-manufacturing accessories will help turn your hydraulic jack into a very useful tool. household installation. In the garage, she will help you press in and out bearings and silent blocks, in the home workshop - glue wooden bars into a strong canvas and bind an old, but very valuable book.
She can even squeeze the juice from the fruits from your garden if you have the appropriate containers.
There may be other design solutions for your home press, but the main mover is a hydraulic jack. And it also seems to us that the design of such a simple pipe bender can lead a thoughtful reader with an engineering mindset to very productive thoughts.
And if this happens, we hope you will share this with the subscribers of our site.
Dear readers, if you still have questions, ask them using the form below. We will be glad to communicate with you;)
Today it is impossible to imagine carrying out a car repair, whether it is a wheel replacement or suspension repair, without the use of jacks - special devices, which are designed to lift the load and fix it at a certain height. And today, hydraulic jacks are considered the most popular, in which force is created using a piston and working fluid.
Hydraulic jack device
Main elements in the design of the hydraulic jack are:
- metal case;
- hydraulic piston;
- working fluid.
The hydraulic jack can have a regular or extended body made of hardened metal. The housing performs the following functions: it is a container for working oil and acts as a guide cylinder for the piston.
This type of unit is equipped hydraulic pump with air, foot or manual drive. The design of the jack contains safety valves and other devices to maintain trouble-free and long operation.
Retractable hydraulic cylinder and lifting mechanism , which raises a special platform, are located in the openings of the body. Lowering occurs by turning the T-handle. The design has built-in wheels that provide mobility to the device. The elongated body of the shooting gallery is usually used to work with heavy vehicles and buses.
Principle of operation
Any hydraulic lifting mechanism works with the use of liquid according to the principle of communicating vessels. Before work, you need to install the unit on a hard and even surface under the machine and, with the valve closed, hold down the lever until the car reaches the required height. The descent of the machine occurs by opening the valve located on the body of the jack.
Working hydraulic oil pumped by a drive pump using a lever. The liquid moves into the cylinder through the valve, squeezing it out. The return flow of oil is prevented by two valves - suction and discharge. In order to lower the jack, you need to open the valve on the pump, in this case, the liquid passes from the cylinder back into the housing.
The presence of threads on the body, protected by a special casing, threaded holes in the base and threads on the stem, guarantees unlimited work of jacks and the possibility of using for bending, clamping and crimping. A sturdy support made of hardened metal and mounted on the stem protects the lifting mechanism from damage. The corrugated part of the base prevents the car from slipping.
Advantages and disadvantages
hydraulic jacks are considered the most unpretentious. The main feature of hydraulics is an incompressible working fluid. The result is smooth lifting of the load, precise braking and fixation at the required height. Hydraulic jacks have excellent efficiency - up to 85% and high load capacity - over 250 tons with little effort, due to high gear ratio between the surfaces of the cylinder and the pump plunger.
But with hydraulic lifting devices, the initial lifting height is much higher, in contrast to mechanical devices. Another difficulty is the impossibility of precise adjustment of the lowering height. To support the jack in the working position, it is necessary to constantly monitor the tightness of the seals and valves, as well as monitor the oil level. These units can only be stored and transported in an upright position, otherwise the liquid may spill out of the housing.
Disadvantages of hydraulic jacks:
- They are rather slow.
- Have big sizes and mass.
- High price.
- Small stroke for single plunger jacks.
Bottle (vertical) jacks
The design of the hydraulic vertical jack is the simplest. The area of use of these jacks is quite extensive due to the significant range of lifted loads - from 3 to 200 tons. Bottle jacks are used in trucks. In addition to the main advantages of a hydraulic jack, bottle models have several more - a large footprint, compactness and versatility of use.
Vertical jacks may be double or single. The single-rod device is distinguished by ease of use and simple design, which expands the scope of its use and makes it possible to perform work of varying complexity:
- dismantling and installation in construction and mechanical engineering;
- repair of wheels of wagons and cars;
- use as a power unit of a pipe cutter, pipe bender, press and similar tools.
The two-rod telescopic jack has a similar design with the vertical one, the principle of operation of the bottle mechanism is based on the installation of several rods. The piston is located at the base of the telescopic device. It can be used in vertical and horizontal position. It fits most cars and has a small size. Lifting occurs with the help of a lifting lever, which is brought into working position by a cylinder.
Rolling jacks
This type of jack works on the same principle as the vertical one, but with the difference that the cylinder is not in a vertical position, while the piston is not directly aligned with the pickup. This device is called rolling due to the fact that it is a cart on wheels that can be rolled over the surface. The jack moves or "rolls" under the load.
This jack is set in motion, like bottle machines, by swinging the lever, it is also lowered by unscrewing the valve screw. If it is necessary to lower the load, then you need to put a tubular handle on the valve screw, then the partition enters the groove of this screw. Turning the handle around the axis, the operator also rotates the screw, thus reducing the pressure in the cylinder and lowering the car to the desired height.
As a rule, a rolling jack is used at a tire changer, as it is ideal for lifting one side of a car, quite fast in installation and operation. The disadvantages of this design come from the name - for the rolling lifting mechanism to work, a solid and Smooth surface, asphalt or concrete. In addition, the large weight and size complicate the transportation of the device in the car.
Rolling jacks divided according to purpose:
- For personal use cars, with a carrying capacity of up to three tons.
- For tire shops and car shops, up to four tons capacity and with pre-lift arms to quickly reach the required pick-up height.
- For special vehicles and maintenance of heavy machines with a load capacity of up to twenty tons and with the installation of pre-lift levers.
hydraulic lifting devices need periodically maintenance, therefore, it is necessary to add oil to the working cylinder, which flows out during operation through various seals and seals. In addition to the question of how to pump a hydraulic jack with your own hands, problems can also consist in jamming while lifting the car to the required height, as well as the inability to lift even a light load or the inability to lower the piston after lifting.
Oil leak
To test or repair a jack with your own hands, you need purchase the required repair kit. Before repair, you must first disassemble the unit. To do this, you may need a wrench extension to get more leverage and considerable force. Also be sure to prepare a container for used oil and prepare a new one.
Then you need to get the pistons and check them for corrosion. All corrosion and dirt must be removed. Make sure the stem is not bent. If the deformation nevertheless occurred, then it is unlikely that you will be able to align it again, so you can finish the repair with your own hands.
It is also worth checking the valve that transfers oil. Why is it unscrewed and checked for dirt or deformation. If the valve is broken due to mechanical deformation, then it simply needs to be replaced. At the same time, it can simply become clogged, and the ball begins to sit loosely in its place. This is the reason for the oil leakage.
Pour out the old working fluid completely. This is a fairly simple procedure, although it will take you a long time while the liquid flows through the cylinders. Oil is drained by pumping the system by moving the lever up and down. Wash all elements thoroughly from oil and dust residues. Fully replace all seals and cuffs.
Another reason for the breakdown of the jack is the dirt that got into the working mechanism. To remove it, you need to unscrew the body head, pour kerosene into the base and pump the jack with the locking needle unscrewed. At the end of the operation, kerosene must be removed and new oil should be poured into the working part.
Entry of air bubbles
During prolonged operation, air bubbles accumulate in the working part of the jack, significantly reducing its performance. Repair of this breakdown occurs in this way.
First, unscrew the bypass valve and the oil tank cap, and then at a fast pace pump the pump several times. So, the air will come out of the working part into the oil tank. After that, you can close the hole that leads to the oil tank and bypass valve. If everything is done correctly, then the air will come out, and the device will again work in normal mode. If the attempt fails, repeat these steps.
So, you got acquainted with the device of a hydraulic jack, studied its advantages and disadvantages, figured out the classification and know how a hydraulic jack is repaired with your own hands. The main thing to remember during its operation is the periodic addition of the working fluid and maintenance.
Man has invented many devices for lifting weights. Briefly describe the principle of their work - the transformation of the distance traveled into effort.
Consider examples of such transformations:
- Lever arm. On the long side, the distance traveled is greater and the effort is less. On the short side, the opposite is true;
- Block system. The cable, passing through a certain number of blocks, loses distance with each loop, proportionally acquiring additional traction;
- Gears with different gear ratios. The small gear turns quickly and with less effort. Large - on the contrary;
- Chain (belt) pair. A smaller diameter pulley rotates effortlessly and faster. Pulley larger diameter develops a high torque on the shaft at a lower rotation speed;
- Communicating vessels. Two piston pairs connected to each other operate on the principle of a lever. A piston of a smaller diameter with a small force moves with a large span. While its larger "brother" moves a short distance with a proportionally increased effort.
A hydraulic jack works on the principle of communicating vessels.
Relatively compact dimensions (compared to the force that the tool can develop) make it indispensable when working with large weights. Portable bottle jacks (this is their second name) develop a force from 1 to 20 tons. Larger specimens can take a weight of 200 tons.
At the same time, it is hydraulics that is one of the safest devices for lifting weights.
Device, features of the use of a bottle-type jack
The illustration shows the components of the hydraulic lift. 
The whole structure fits inside the reservoir with the working fluid. The lifting rod in the lower position is completely recessed into the body. The handle-lever is removable, and in the transport position does not take up much space. Therefore, jacks of this type easily fit in the trunk of a car.
IMPORTANT! Store hydraulic bottle jacks in an upright position. Otherwise, the operating fluid may leak out.
A device capable of lifting a solid SUV (force 5 tons) - has dimensions (taking into account the unfastened handle) not more bottle wine volume of 0.7 liters. One person can handle such a jack.
Hydraulic jack device and principle of operation is based on physical properties liquids that retain their volume during compression.
The hydraulic jack is a portable lifting device designed for heavy objects.
The purpose of the hydraulic jack
A hydraulic jack is a stationary, portable or mobile lifting device designed for heavy objects. It is used when performing repair and construction work and as part of cranes, presses, hoists.
Modern designs of hydraulic devices are used at the enterprises of the oil refining industry, facilities of the energy sector of the industry, in agriculture. High level productivity and efficiency index, ease of operation and maintenance allow the use of hydraulic jacks in the domestic sector.
This type of equipment is able to easily operate both in horizontal and vertical positions, which has found its application on sites for installation and construction work. The unit is used for tensioning reinforcing structures made of stressed concrete.
The structure of the hydraulic lifting device
The unit is set up as follows:
- frame;
- working fluid;
- working piston.
The design of the device can have an elongated or short body, for the manufacture of which hardened special steel is used. The body of the device is assigned to perform several functions. It is a guide cylinder for the working piston and serves as a reservoir for storing the working fluid.
A screw with a lifting heel is capable of being screwed into the plunger using a special thread. By unscrewing it, you can change the maximum height of the jack heel. Hydraulic devices are equipped with working pumps that have a manual, foot or air drive. The design provides for the installation of safety valves and some structural elements ensuring long and trouble-free operation of the lift.
The hydraulic pump and the cylinder with the piston are arranged in such a way that they provide the extension and lifting of the special platform. After the extension of the stem, return to initial position carried out using a bypass valve.
There are several different modifications of lifting hydraulic units, which have their own areas of application.
The most common are:
- bottle type devices;
- rolling type devices;
- hydraulic jacks of hybrid design;
- hook-type units;
- diamond aggregates.
Various designs of hydraulic jacks have their own characteristics in the device, which are determined by the scope of the device.
Each of the types of hydraulic jacks is designed in its own way, however, the principle of operation is the same for all.
The principle of operation of the hydraulic jack is based on the use in the design of the apparatus of communicating vessels with a working fluid, the role of which is played by a special oil. Before use, the device must be placed on a flat, solid surface and the bypass valve closed. After installation and preparation of the unit, you can use it in operation.
The rod is lifted from the fifth by means of a pump that injects the working fluid into a special cylinder.
Due to the property of the liquid to resist compression with increasing pressure, the piston moves in the working cylinder. This leads to the movement of the rod with the lifting heel. The descent of the latter occurs by opening the bypass valve counterclockwise.
Pumping of working oil is carried out by a drive pump and a lever mounted on it. The oil moves from the pump to the working cylinder through special valve.
The return of liquid during the operation of the device is prevented by two valves: discharge and suction.
To install the lift in its original position, a special valve is provided in its design, when opened, the working fluid flows from the cylinder to the pump of the unit.
The presence of a screw under the working heel in the jack device allows you to expand the possibilities of using the device.
For lifting, a special heel is made of high-strength steel. The force of the hydraulic jack is regulated by a built-in pressure gauge.
Advantages and disadvantages of hydraulic jacks
The physical features of the liquid allow for a smooth lifting, lowering of the load and fixing it at a certain height. Hydraulic jacks provide high efficiency, which reaches 80%. The carrying capacity of the unit is due to the presence of a large gear ratio between the cross-sectional indicators of the pump and working cylinder, plunger.
It is necessary to regularly flush the hydraulic jack, as well as change the oil and pump it.
Hydraulic lifts have a number of disadvantages. First of all, it should be noted that any model of this equipment has a certain starting height for lifting the load, below which the device cannot be operated. The disadvantage of this equipment is also the inability to accurately adjust the height of the lowering. In order to ensure trouble-free operation of the device, it is recommended to constantly monitor the cleanliness, quality and level of oil in the jack reservoir. The normal operation of the device is ensured by the tightness of the valves and glands used in the design of the unit. Transportation and storage of the device is carried out exclusively in a vertical position, if this requirement is violated, the working fluid can flow out of the device reservoir.
One of the disadvantages is the slowness of the units in operation. The disadvantages also include the weight of the device, its large size and high cost. In addition, single-plunger devices have a small stroke of the working rod, which is another drawback.
Possible malfunctions in the operation of the hydraulic jack
In any case, hydraulic jacks require care and maintenance, which consists in adding oil to the working tank of the unit. In addition, after a certain period of operation, it is required to flush the fixture, change the oil and pump it. Oil from the working reservoir can leak through the seals and various seals used in the design of the device. In addition to leakage during operation of the device, malfunctions such as jamming during lifting and the impossibility of lowering the rod may occur.
To eliminate oil leakage during the operation of the device, seals and seals are replaced. For this purpose, specially designed repair kits are used. During the repair process, the unit is disassembled, the seals are replaced, the hydraulic jack is assembled, after which the working fluid is filled and pumped.
To eliminate jamming, the device is disassembled and its components are inspected for corrosion and contamination. If the first one is detected, special processing and the dirt is washed away.
How to pump a hydraulic jack is a very common question among car owners. But it is also worth knowing about the device and types of the unit.
Many car owners want to assemble a rolling jack with their own hands. This greatly simplifies the processes of repair, car maintenance, eliminates the need to visit service stations and spend money on the purchase of factory jacks.
The jack itself is a device designed to lift a load to the required height. Such units are widely used in everyday life and industry, while differing in size and power.
The load lifting device is used for:
- Fixations;
- moving;
- Lifting heavy parts;
- in the construction industry;
- When disassembling a car, changing wheels, etc.
At the same time, the main distinguishing feature is the carrying capacity. Some models are designed to lift several tons, while others are designed to lift hundreds of tons of weight.
Hydraulic jack device
To make a calculation of a hydraulic jack for its purchase or self assembly, it is recommended to find out which scheme, device and design features at this device.
The lifting device consists of three main components:
- Movable piston;
- Corps. It is made of high-strength metal, has the shape of a cylinder. In addition to the functions of the body, it plays the role of a container where the oil is located;
- liquid environment. Engine oil acts as it;
- Levers;
- valves;
- Plungers.
- Force is applied to the lever, and the use of valves makes it possible to increase it tenfold.
- The plunger allows you to move the piston device by transferring the working fluid, which acts as oil, into a container under the plunger.
- Due to the valve, the oil does not flow back into the housing.
- Gradually, the plunger transfers more oil under the piston, which helps it rise.
- To lower the load, it is necessary that the oil returns to the hull device. Here you need to open the valve.
A similar principle of operation is relevant for all hydraulic jacks. Therefore, the diagram, drawings, video manuals for the assembly and operation of these devices are approximately the same.
Advantages and disadvantages
If you decide to assemble a bottle-type lifting device, thereby creating a hydraulic jack, or you want to buy factory equipment, you should first learn about the strengths and weak sides that characterize the device.
Let's start with the benefits, which include:
- High power ratings;
- Ease of operation;
- High efficiency, reaching 80 percent;
- The device works when moving loads weighing up to 200 tons. So the hydraulic jack raises a decent mass.
But this type of jack has its drawbacks. They should be known before starting work on it.
- The device cannot lift a load from a low height.
- Inability to set the level of lowering parts.
- A device of this type requires close attention, periodic maintenance. The service maintenance scheme provides for the need to fill in oil, change oil seals, gaskets.
- The hydraulic jack can only be transported and stored if it is vertical arrangement. Otherwise, oil flows out, it has to be refilled for normal operation. Refueling the unit is not difficult, but no one wants to do it all the time.
- The principle of the device does not allow it to quickly perform the functions of lifting and lowering.
- The rise is carried out cyclically.
- This type of device is quite expensive.
- Breakdowns for hydraulic jacks are not uncommon, and they are quite expensive to maintain.
Types of hydraulic jacks
Take the factory or collect homemade - you decide. Hydraulic jacks on the market different type. Each of them has its own characteristics, which you should know about before buying the device.
- bottle type unit. The most common and at the same time the most structurally simple variation of the hydraulic jack. Bottle lifts lift loads up to 100 tons, have an impressive footprint and a compact body. Widely used for work at car services. The bottle hydraulic jack has two modifications - single-rod and two-rod. The former have simple design, are used in the construction, repair of railway cars, in the manufacture of pipe bending, pipe cutting units. The two-rod mechanism can work in vertical and horizontal position.
- Rolling. The rolling device looks like a trolley moving under a lifted load. The control is carried out by a hand lever, the adjustment is carried out by oil valves. It shows itself perfectly when lifting a load on one side, it is important to use it when replacing wheels on a car. But for work, a flat, hard surface is required. It happens to be homemade.
- Hybrid. It combines a bottle and rolling hydraulic jack, is widely used in car services. Management is carried out by levers and foot pedals.
- Diamond. Relevant for car service. Its supporting structures are connected by hinges and form a rhombus, which influenced the name of the device. Compact, relatively light, easy to transport.
- Toe. They are used where it is necessary to lift a load from a small height. For its work, a bottle scheme is used. May be homemade.
Assembling a home-made unit with your own hands, or buying a bottle-type hydraulic factory jack is your personal decision.
Repair and pumping
The principle of operation is clear. It remains to figure out how to repair and pump the device. What kind of oil you will fill in when changing or topping up, rely on the manufacturer's factory instructions.
The most common breakdowns of hydraulic jacks include the following:
- lack of oil;
- Excess air inside;
- Formation of rust, dirt;
- Deformed stock.
In this case, you will need to repair and pump your hydraulic jack.
- As operation progresses, oil will flow out of the hydraulic jack, resulting in the need to periodically add hydraulic fluid. Topping up is done with a repair kit.
- Before starting maintenance, prepare a container where the old oil will be drained, prepare fresh liquid for filling.
- Unscrew the fasteners with wrenches, remove the drain valve, the jack piston.
- Clean the pistons, remove dirt, rust, check them for integrity.
- From outside to inside, frequent the bleed valve. The presence of defects on it indicates the need for replacement.
- When inspecting the valve, do not lose the metal ball. If it does not fit snugly, the jack will not work properly.
- Drain the old oil by bleeding. To do this, move the lever up and down until all the oil flows into the master cylinder.
- Clean all parts after draining, replace cuffs, gaskets.
- It is advisable to wash with kerosene. Pour it inside the jack, pump it, after removing the locking needle. Remove the kerosene by pumping, fill the container with new oil.
- If an air lock has formed in the jack, remove the oil tank cap, open the valve and pump several times. Then open drain valve and replace the plug.
The principle of pumping, maintenance does not cause problems, because each user can repair the hydraulic jack with his own hands.
