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What does a hydraulic jack consist of in everyday life? What is a jack?, description of a jack, device of a jack, types of jacks

What does a hydraulic jack consist of in everyday life? What is a jack?, description of a jack, device of a jack, types of jacks

GENERAL INFORMATION

Older cars were equipped with screw and rack and pinion jacks with a load capacity of 500 kg or more. For such jacks with a folding support, special lug sockets must be provided on the car body, which are often clogged with dirt and ice or deformed, which makes their use difficult. Incorrect installation results in damage to the side surfaces of the fenders, doors or sills. In addition, if the sills and sockets are weakened by corrosion, there is a danger of the car falling, and not all jacks supplied with the car have acceptable stability and adaptability to various situations.
Today, from a huge variety of modern jacks, you can choose devices that meet the requirements of both a motorist who intends to carry it with him and use it only for his car, and a large car service center that constantly services cars of different classes.

MAIN CHARACTERISTICS

Load capacity(indicated in kilograms or tons) - the maximum force that the jack can develop. It must be no less than the lifting capacity of a standard jack or half the curb weight of the vehicle.
Support platform– lower support part of the jack. Its dimensions should ensure minimal indentation into the ground at a given load capacity, and the protrusions (shape) of the surface should prevent lateral sliding of the jack.
Pickup– part of the jack designed to rest against the vehicle or the load being lifted. On screw or rack jacks for older models of domestic cars, it is a folding rod; on others, as a rule, there is a rigidly fixed bracket (lifting heel).

Minimum (initial) pickup height(Н min) – the smallest vertical distance from the supporting platform (road) to the pickup in its lower working position. The initial height should be small so that the jack fits between the road and the suspension or body elements.
Maximum lift height(Н max) – the greatest vertical distance from the support platform to the pickup when lifting the load to its full height. An insufficient H max value does not allow the jack to be used for lifting vehicles or trailers in which the places intended for installing the jack are at a high height.
Maximum stroke jack (L max) – the largest movement of the pick-up vertically from the lower to the upper position. If this parameter is insufficient, the jack may not “tear off” the wheel from the road.
Force on the drive handle– the force that must be applied when lifting a load. Depends on the weight of the vehicle being lifted and the type of jack. In some species it changes during ascent.
Sustainability– the ability of the jack to maintain its working position under the influence of forces tending to move the car in the longitudinal or transverse direction. These forces arise when the jack itself is tilted, due to a gust of wind, road slope, etc. Stability mainly depends on the size of the supporting platform and design features.
Versatility– the jack is suitable for lifting cars of all types under various road conditions, as well as during repair work: as a power element, for removing a tire, etc.

HYDRAULIC BOTTLE JACKS

They have a load capacity from 2 to 100 tons or more, and come in single- and multi-plunger (telescopic) types. The load-bearing elements are not only the body and the retractable plunger (piston), but also a special liquid (working fluid). The housing is both a guide cylinder for the plunger and a reservoir for the working fluid. The lifting heel of jacks with a lifting capacity of up to 20 tons is located in the upper part of the screw screwed into the plunger. This allows, if necessary, by turning out the screw, to increase the initial height of the jack.
The force from the drive handle is transmitted through the lever to the injection pump. When it moves upward, liquid from the reservoir enters the pump cavity, and when pressed, it is squeezed into the cavity of the working cylinder, pushing out the plunger. Backflow of liquid is prevented by valves. To lower the load, the locking needle opens and the working fluid is forced out of the cavity of the working cylinder back into the reservoir.
There are designs of hydraulic jacks, where an electric motor connected to the vehicle’s on-board network or a pneumatic drive is used to drive the pump.
When choosing a hydraulic bottle jack, it is necessary to take into account not only its load capacity, but also the pick-up and lifting heights, since the working stroke with sufficient load capacity may not be enough to lift the car. They require monitoring the fluid level, condition and tightness of the seals. If such jacks are not used frequently, it is recommended not to fully tighten the locking mechanism during storage. Their operation is only possible in a vertical position and only, as with any hydraulic jacks, for lifting, and not for holding, a load.

(+) Low force on the drive handle, rigidity of the structure.
(-) The complexity of the device, large weight and initial height, often insufficient stability, small stroke (for single-plunger ones).

ROLLABLE HYDRAULIC JACKS

They are a low housing on wheels, from which a lever with a lifting heel is raised by a hydraulic cylinder. Convenience of work is facilitated by removable platforms that change the pick-up and lifting heights. In compact models, the handle is foldable and is not multifunctional.
Rolling hydraulic jacks can be divided into three groups.

FOR PERSONAL USE

Their carrying capacity is up to 3 tons.
(+) Fast lifting, long stroke.
(-) Fragility of the structure.

FOR CAR SERVICES AND TIRE WORKSHOPS

They have a lifting capacity of up to 4 tons. They can have a pre-lift pedal to quickly obtain the desired pick-up height.
(+) Structural rigidity, good stability, quick lifting, long stroke.
(-) Ability to work only on flat and hard surfaces.

FOR SERVICING HEAVY VEHICLES AND SPECIALTY EQUIPMENT (INCASHMENT, AUTO-LOADERS, ETC.)

They have a carrying capacity from 2 to 20 tons.

They can also be equipped with a pre-lift pedal and allow the use of additional devices, such as a sliding crossbar to raise the side of the car. On some models, you can use the drive handle to raise or lower a load, as well as transport a jack.

(+) Structural rigidity, good stability, lifting height when using additional devices can reach up to 1 m.
(-) Heavy weight (from 60 to 225 kg), prompt preparation of the jack for work is difficult.

ROLL-OUT SCISSOR JACKS

Lifting is carried out by extending the piston from the hydraulic cylinder, while changing the angle between the hinged levers. Sometimes they have two lift levels, which makes it possible to lift cars with low ground clearance to a considerable height. They can be equipped with a cardan control system, a pressure valve and a carrying handle. The lifting capacity of such jacks is usually from 4 to 7 tons.
(+) Structural rigidity, mobility, low force on the drive handle, small initial height, significant lifting height.
(-) Heavy weight, high cost, ability to work only on flat and hard surfaces.

PNEUMATIC JACKS

The load is lifted by supplying compressed air. These jacks can be made in a rolling version, have a low initial pick-up height and a load capacity of 2 to 40 tons. They are used only as auto service equipment.
(+) Good stability, no lifting effort on the part of a person, small initial height, significant load capacity.
(-) Heavy weight, high cost, ability to work only with compressor equipment.

RHOMBIC HYDRAULIC JACKS

The lifting capacity of such jacks is 1-2 tons. They have four hinged, diamond-shaped levers as load-bearing elements.
Lifting is carried out by changing the angles between the levers, which increases the distance between the supporting platform and the pick-up. For ease of storage and transportation, diamond jacks can be supplied in a plastic case.
(+) Rigidity of the structure, low lifting force, large supporting surface.
(-) Considerable weight.

TWO-STAGE JACKS

They have two levels of pickup - one is located at the upper end of the cylinder, and the second is provided by a platform connected to its lower boundary. Such jacks are designed to work with heavy equipment and have a lifting capacity of 5 to 25 tons.
(+) Rigidity of the structure, good stability, low force on the drive handle, low initial height, significant lifting height.
(-) Heavy weight, high cost.

HIGH JACK RACK JACKS

The design of these jacks dates back more than 100 years. The main load-bearing element of this design is a rail with holes. A mechanism with metal fingers moves along the rail, which snap together and raise the grab handle, as if on a ladder.
The “up-down” switch allows you to move in the desired direction by one rack hole with each stroke of the drive handle, and step-by-step lowering under load is also possible. Using an extended handle reduces the effort when lifting.
To operate safely with jacks of this type, you must comply with the relevant operating instructions (must be supplied with the jack). Such devices with a high lifting height are popular among off-road driving enthusiasts, since its instability is used to free a stuck vehicle from a rut, and the design of the jack allows it to be used as a winch. High Jack rack and pinion jacks have a lifting capacity of 3 tons.
(+) Large working stroke and maximum height, constant force throughout the entire working stroke, ease of use, versatility.
(-) Large weight and dimensions.

INFLATABLE JACKS

They are an airtight shell (cushion), which is filled through a hose with exhaust gases from the exhaust pipe to lift the car.
They can be placed under the car regardless of the location of the jack support points on the body. You only need to be wary of contact with elements of the exhaust system that have a high temperature. The inflatable jack works on any type of road surface, even snow or mud, and has a lifting capacity of up to 4 tons, while lifting the car in less than one minute. They can be left under load for no more than 5-10 minutes, for example to change a wheel.
The kit includes two mats that improve protection against dirt and damage to the pillow, as well as a bag for compact storage of the device.
(+) Good stability, ease of use, compactness in transport position, minimum initial height, low weight (2-3 kg), quick lifting (up to 1 min).
(-) Requirements for the absence of leaks in the exhaust system. After working on a dirty road, part of the surface of the cushions and mats become dirty and require cleaning.

When working with jacks, you must follow basic safety rules.
When replacing a wheel or carrying out repair work with the vehicle suspended, the following is required:
fix the wheels on the side opposite to the jack in both directions; for this you can use special shoes;
after raising the body to the required height, regardless of the design of the jack, install a reliable stand under the load-bearing elements of the body (sills, side members, etc.). Never work under a car if it is only supported by a jack!
install the jack in such a way that when the car is raised, the possibility of slipping or falling off is minimal.

Cranes, etc.) is the fact that the jack is located below, and not on top of the load being lifted, which makes it possible to do without various auxiliary structures, chains and ropes.

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Types of jacks

Screw jacks

Screw jacks are used for repair work when it is necessary to install a load both on top of the rotating heel and below on the foot. Usually these are standard jacks for various types of cars. Load capacity - up to 15 tons.
Such a device consists of a cylindrical base and one or two lifting screws placed inside it, which extend or retract depending on the direction of rotation of a special gear nut with a trapezoidal thread.
In most cases, a screw jack is reliable in operation. This is due to the fact that the load is fixed by a trapezoidal thread and when it is lifted, the nut rotates idle. In addition, the advantages of these tools include strength and stability, and the fact that they can work without additional stands.
Combined lever-screw jacks have such advantages as low price, high lifting height, small dimensions and low weight, and balance out some of the disadvantages of the tool (poor stability and inconvenient drive handle).

Rack jacks

Rack jacks are widely used when performing repair, installation and dismantling, construction and other work. They come in lever and gear types. Devices of the first type are equipped with a swinging drive lever, which extends the rack. In gear jacks, instead of a drive lever, a gear is installed; it rotates using a drive handle. To hold the load in the desired position, a ratchet with a pawl is provided on the axis of one of the gears. In both types of jacks, the main part is a load-carrying rail with a support cup, on which the load is held using locking devices. The lower end of the rail is bent at an angle of 90°, which allows you to lift loads with a low supporting surface. An important feature of the rack jack is the low location of the lifting platform. In some models the distance from it to the floor is 90 mm
Rack and pinion jacks have one-, two- or three-stage transmission - for lifting loads weighing up to 6 tons, from 6 to 15 tons and over 15 tons, respectively. These devices operate in both vertical and horizontal positions.
These devices are simple and easy to maintain, their maintainability is high, and their load capacity ranges from 2 to 20 tons.

Hydraulic jacks

Hydraulic jacks, as the name suggests, operate on liquid. The principle of their operation is based on moving the piston (plunger) of the jack with the help of the pressure-creating working fluid (hydraulic oil) of the drive pump, due to which the load is lifted. The weight is lowered when liquid is pumped from the glass into the pump reservoir.
Hydraulic jacks are distinguished by: high load capacity combined with low working force due to the high gear ratio between the cross-sectional areas of the cylinder and the pump plunger; high efficiency, smooth running, rigidity and compact design. However, their initial lifting height is much higher than that of mechanical jacks. Another difficulty is that it is impossible to accurately adjust the lowering height. In addition, these tools can suffer significantly more serious damage than mechanical lifting devices. The lifting capacity of hydraulic jacks ranges from 1 to 1000 tons. There are many variations of the mentioned devices - these are classic bottle jacks (single-rod and telescopic), rolling jacks, and special jacks - diamond-shaped, two-level and hook-type. The bottle-type hydraulic single-rod jack is distinguished by its simplicity of design and ease of operation, which expands its scope of application and allows it to effectively perform work of any complexity. It is actively used for installation and dismantling in any industry (mechanical engineering, construction, etc.), it is suitable for repairing cars, wheelsets of railway cars, and also as a power unit for presses, pipe benders, pipe cutters and other similar tools. It should be remembered that in order to prevent the leakage of working fluid from the reservoir, the bottle jack must be transported and stored in a vertical position, since in a different position oil leaks may occur during transportation. The design of a hydraulic double-rod (telescopic) jack is similar to the design of a single-rod device; it differs only in the presence of a telescopic rod. This feature allows you to lift the load to a greater height, compared to a classic bottle-type jack.

Pneumatic jacks

Pneumatic jacks are designed for lifting (moving) loads during installation, repair and rescue work. They are indispensable in the case of a small gap between the support and the load, for small movements, for precise installation, and if there is work to be done on loose, uneven or swampy soil. Pneumatic jacks are used for joining pipelines of large diameters (up to 1200 mm), centering them in casings and when installing supports, as well as for installing and leveling large-capacity tanks, carrying out repair and construction work at any facility.
A pneumatic jack is a flat rubber-cord shell made of special reinforced fabric, which increases in height when compressed air (gas) is supplied to it. The source of compressed air (gas) can be stationary or mobile compressors, as well as automobile compressors (pumps) or cylinders with compressed air or inert gas.
The main disadvantage of pneumatic jacks is their high cost. It is influenced by: the relative complexity of the design, associated mainly with sealing the joints, the expensive technology for manufacturing hermetic shells and, finally, small industrial batches of production. It should also be noted that the pneumatic jack cannot be used when the engine is stalled and it is unsafe when deflated; the load capacity of this device is determined by the operating pressure in the pneumatic drive.

There is a legend that in ancient times the jack was used in military operations as a tool that was used to break down the gates to a besieged city. For this reason, the design of the jack was classified. According to legend, the jack's design was sold (one of the first cases of espionage known to history). According to another version, a wandering artist painted a portrait of a nobleman who was leaning on a jack. After which the artist reproduced the drawing and gave (or sold) it to the warring party.
The idea of creating the world's first automotive hydraulic lift was born by chance. Its author, Peter Lunati, who was engaged in car repairs, during a visit to the hairdresser saw how the master easily fixed the chair at the desired height. Less than a year later, in 1925, Lunati produced an automobile platform lift with a central hydraulic rack, powered by a hydraulic unit with a manual

Car enthusiasts have different attitudes towards jacks: some consider it an ordinary piece of iron, some see it as an assistant who has helped out more than once in critical situations, some see it as an “instrument of torture,” they say, “...it’s hard to lift it up and it’s hard to put it down.” , and you’ll rip your hands off on the asphalt...”
To each his own, but a lot depends on the type of jack and the ability to handle it correctly.

For example, my first acquaintance with an ordinary screw jack did not bode well. The “harmful tool” tried to rip off the sides of the car, which he eventually achieved, leaving another “battle scar” on the wing of the already battered Zhiguli. But after a while, either his conscience woke up in him, or I became more careful, but the relationship between us improved and there was complete “mutual understanding.” Now, “pumping up my muscles” with a diamond jack, I increasingly remember my “old friend”, who easily raised and lowered the car.
But from nostalgia to action.
First, let's look at the main characteristics, advantages and disadvantages of individual types of jacks, that is, everything you need to know when choosing this important automotive accessory.

MAIN CHARACTERISTICS OF JACKS

Load capacity - the maximum force developed by the jack (indicated in kilograms or tons).
The catch is the part of the jack designed to rest against the car. It can be made in the form of a folding rod (for screws and most rack and pinion ones) or a rigidly fixed bracket called a lifting heel (hydraulic, rhombic, etc.).
Support platform - the lower supporting part of the jack. There are two requirements for it. The first is to prevent lateral slip (achieved through the shape of the surface). The second is to ensure minimal indentation into the ground at a given load capacity.
The minimum (initial) pick-up height is the smallest vertical distance from the support platform to the pick-up in its lower working position.
The maximum lifting height is the greatest vertical distance from the support platform to the pickup when lifting the load to its full height.
The maximum working stroke is the greatest movement of the pick-up vertically from the lower to the upper position.
Handle force is the force that must be applied when lifting a load. This parameter depends on the weight of the vehicle being lifted and the type of jack. In some species it changes during ascent.
Stability is the ability of a jack to maintain its working position under the influence of forces tending to move the car in the longitudinal or transverse direction. These forces can occur if the jack is not properly installed (tilted), due to the slope of the road or a strong gust of wind.
Stability mainly depends on the area of the supporting part and how rigidly it is connected to other parts of the jack.
Versatility - the jack is suitable for lifting cars of all types with various ways of installing them.

TYPES OF JACKS

Screw jacks

Most car enthusiasts call them “Zhiguli”, since for more than 30 years rear-wheel drive VAZs have been equipped with screw jacks, and since 1977, the “extended” version has been included in the Niva tool kit.
Loading capacity of screw jacks is from 0.5 to 1 ton. The role of load-bearing elements is performed by a steel body and a small-diameter screw. The torque from the drive handle is transmitted to the screw through bevel gears. Depending on the direction of rotation of the handle, the screw raises or lowers the folding arm.
For lifting, there are special lugs on the bottom of the car, which, due to their unfortunate location, are constantly clogged with dirt, and in winter they also freeze, which makes it impossible to lift the car.
After several “salty” winters, the lugs can become so weakened due to corrosion that when the car is lifted, they simply burst along the seam and the car crashes to the ground. We think it’s not difficult to guess what this threatens the driver with. Take care of your hands, gentlemen!
When choosing a screw jack, the owner of the Niva should pay attention to the markings: jack for the “classic” - 2101-3901250 (maximum lifting height 470 mm), for the Niva and its modifications - 2121-3901250 (maximum lifting height 510 mm). Otherwise, using the standard Zhiguli jack on the Niva, it will be possible to replace only the front wheels. This is due to the fact that the rear suspension of the VAZ SUV has greater free play, and the jack 2101-3901250, raised to the maximum height, will not be able to lift the rear wheels off the ground.
ADVANTAGES screw jack: small and stable force on the drive handle, significant stroke and maximum lifting height, light weight and low price.
FLAWS screw jack: small support area and, as a result, insufficient stability, large overall dimensions.

Old car models, for example GAZ-21 Volga, were equipped with such jacks; their load capacity was 0.5 tons or more. The main load-bearing element of the structure is a one-sided toothed rack along which the body of the ratchet mechanism with a folding catch attached to it moves. You can change the direction of movement using the up-down switch.
Modern models with a lifting capacity of 2-2.5 tons or more are capable of lifting a car to a height of 1 meter (and this is not the limit!), in addition, thanks to the presence of special loops, they can be used as a hand winch. All this was appreciated by off-road enthusiasts who have come to terms with a weight of one and a half to two dozen kilograms and meter-long dimensions of rack and pinion jacks.
ADVANTAGES: large stroke and maximum lift height, constant force throughout the entire stroke.
FLAWS: impressive weight and dimensions (especially in modern models).
Post-screw jacks

Such jacks are mainly equipped with Gazelles and UAZs, and their load capacity ranges from 0.8 to 3 tons.
There are two load-bearing elements: a body and a large-section screw. According to their design, rack-screw jacks are divided into single-screw and double-screw.
The operating principle of single-screw jacks is as follows: the drive handle, through a pair of bevel gears, rotates the support nut relative to the body, extending the screw with the lifting heel. For double-screw ones, the supporting nut is the body itself. A second screw with a larger thread in a different direction is screwed into the inside of a large-diameter screw. The rotation of the drive handle is transmitted through a ratchet mechanism to a large diameter screw, and it extends out of the housing, while another screw extends out of it, increasing the lifting height.
ADVANTAGES: structural rigidity, good stability.
FLAWS: large weight and initial lift height, low lift height (for single-rotor ones).

They are equipped with front-wheel drive VAZs of the “eighth” family. Although such jacks can be called universal, since they can be used to lift almost any car whose weight does not exceed 1 ton (load capacity no more than 0.7-0.8 tons).
Load-bearing elements: power screw and two levers (upper and lower).
On the top there is a catch and a screw nut, and on the bottom there is a hinged stop for the screw and a support platform.
The principle of operation is as follows: rotation of the drive handle increases the angle between the lower arm (with the support platform) and the upper arm (on which the pick-up is located), thereby providing lifting.
ADVANTAGES: low weight and initial lifting height, long stroke.
FLAWS: poor stability and insufficient structural rigidity, increased force on the handle at the beginning of the lift.

Hydraulic jacks

They can be called “heavy artillery” - their carrying capacity is from 1 to several hundred tons. This determines their use in the repair of trucks and other heavy equipment. By design they are divided into single and multi-plunger.
The main load-bearing elements: a housing, a retractable piston (plunger) and a working fluid (usually oil). The housing performs two functions: it is a guide cylinder for the piston and a reservoir for the working fluid. A screw with a lifting foot is screwed into the plunger, thus, by turning out the screw, you can, if necessary, increase the maximum lifting height.
The force from the drive handle is transmitted through the lever to the injection pump. When moving upward, liquid from the reservoir is sucked into the pump cavity, and when pressed, it is pumped into the cavity of the working cylinder, pushing out the plunger. The reverse flow of liquid is prevented by valves (suction and discharge). To lower the load, it is necessary to unscrew the shut-off needle, and the liquid is forced out of the pump cavity back into the reservoir.
Hydraulic jacks, for all their power, are among the most demanding. For example, to maintain the jack in working condition, it is necessary to regularly monitor the oil level and monitor the tightness of the seals and valves. Such a jack can only be transported and stored in a vertical position, otherwise the working fluid (oil) may leak out of the tank.
ADVANTAGES: rigid structure, good stability, low force on the drive handle
FLAWS: large mass and initial lift height, complex device, small stroke (for single-plunger ones), high cost.

You can find two types in stores: mechanical (screw) and hydraulic. At one time, front-wheel drive Moskvich cars were equipped with mechanical jacks of this type.
Loading capacity ranges from 0.7 to 2 tons.
As load-bearing elements in this design, four hinged levers are used, forming a rhombus (hence, in general, the name).
The load is lifted by changing the angles between the levers, which accordingly leads to an increase/decrease in the distance between the pickup and the support platform.
ADVANTAGES: structural rigidity, large supporting surface, versatility.
FLAWS: small stroke, increased force on the drive handle (for mechanical ones), high cost and large weight (for hydraulic ones).

This is a kind of symbiosis of lever and rhombic jacks. Currently, they are used to equip the VAZ “ten” family. Compared to lever jacks, these jacks have a slightly higher load capacity - about 1 ton, and the operating principle is almost the same.
ADVANTAGES: small initial height and weight, compactness (if desired, the jack can fit into a 13-inch spare wheel).
FLAWS: poor stability, increased force on the drive handle, low structural rigidity.

This is purely garage or service equipment; it is not worth using it on the road (and especially on a slope), as there is a high probability of the jack breaking. Load capacity from 2 tons or more.
In fact, it is a hydraulic jack of a modified design: a low steel body on small wheels, from which a lever with a lifting heel is extended by a plunger. As a rule, for ease of operation, they are equipped with a long drive handle, due to which the applied force is reduced and it becomes possible to perform all operations with the jack while standing.
ADVANTAGES: good stability, small initial height, structural rigidity, low force on the drive handle.
FLAWS: high cost, the ability to work only on flat and hard surfaces, large mass.
It is worth considering that we have considered only the basic designs of jacks, and if we talk about professional equipment, there are also the following: pneumatic rolling jacks (well suited for work in tire shops), combined bottle jacks (hydraulics/pneumatics), two-level rolling jacks, hydraulic hook ones, carriage ones etc.

TEST PROCEDURE

We decided to test the jacks according to the “full program”. First, we determine the main geometric characteristics: the minimum (initial) pick-up height (H min), the maximum lift height (H max) and the maximum working stroke (L max). Secondly, we measure the force on the drive handle (kg) at the beginning/middle/end of the lift. Next, we will evaluate the stability of the car on each jack (on a five-point scale). Finally, we weigh and determine the overall dimensions (length/width/height) based on the maximum values.
The tests were carried out on a VAZ-2112 car (kerb weight 1.01 tons), GOODYEAR Ultra Grip 400 tires, size 175/70R14. The surface under the support platform is hard and level (concrete).
It is worth considering that some models of jacks were installed directly under the “flanging” of the bottom of the car, which increased H max by 10-15 mm, while the design of the lifting heel of others did not allow this.

USEFUL TIPS

And finally, some useful tips that will help you avoid troubles when working with jacks and forced repairs on the road.
. If a malfunction catches you on the way (for example, a flat tire), then turn on the hazard lights and, gradually reducing your speed, look for an area with a flat and hard (as far as possible) surface for repairs. In the city, do not park your car near an intersection or traffic light; it is better to drive a few meters on a flat tire than to cause an accident. After stopping the car (in accordance with clause 7.2 of the Russian Traffic Regulations), it is necessary to place an emergency stop sign behind the car at a distance of at least 15 m in populated areas and at least 30 m outside populated areas. After this, you can safely begin troubleshooting.
. It is advisable to begin dismantling a flat tire by preparing the necessary tools, a jack and a spare wheel. Then, having secured the wheel located diagonally from the one being replaced with wheel chocks in both directions, install the jack (without lifting the car!) and make sure that it is level, without distortion. Next, loosen the wheel fasteners (nuts or bolts) and begin to smoothly lift the car, while monitoring the longitudinal displacement of the body, and at the slightest hint of it, lower and reinstall the jack. When the distance between the suspended wheel and the ground reaches 30-50 millimeters, unscrew the fasteners, remove the deflated one and install a new wheel. Having completed the repair and put the car on all fours, do not forget to finally tighten the fasteners and measure the tire pressure.
. If you are working with a jack in the garage, then after raising the car, be sure to place additional supports (tripods, bars, etc.) under the load-bearing elements of the body.
Working under a car that is standing only on a jack is strictly prohibited!
. When you become the proud owner of a car trailer, make sure that your car jack has a sufficient maximum lifting height and can, if necessary, hang its wheel.

Diamond jack

In our opinion, this is a worthy representative of the family of diamond jacks, devoid of many of the shortcomings of its “relatives”.

The strength elements of the design inspire confidence, while the jack is compact and lightweight, so there will be no problems with its placement in the car. The profile of the lifting heel makes it possible to substitute it under the “flanging”, increasing the maximum lifting height. The length of the removable drive handle is 470 mm, and the length of the lever is 150 mm, which significantly reduces the applied force and allows you to avoid injuring your hands during operation (which is usually the case with rhombic jacks with a folding non-removable handle). The jack lifted the front wheel of the car by 70 mm (with the required 30-50 mm). We gave it a solid “B” for stability, and although testing took place in almost “ideal” conditions, this hero will not let you down on the road.

The jack is packaged in a cardboard box, which will likely not last long. There are no instructions in Russian. A sticker on one of the levers reads (English): “When changing wheels, you must put the handbrake on the vehicle and block the wheels on the opposite side of the one you are changing. Do not exceed the permissible load - 1 t."

PRICE: Moscow average $9.5.

A worthy replacement for the standard jack of Zhiguli, Samar and Lad. It is more convenient, more stable and more beautiful. If handled correctly, it will last you for many years, the only pity is that there is no transport bag or case.

Combined lever-screw jack

A combination jack should combine all the advantages of a lever and diamond jack, and it is, but it would not hurt to get rid of the shortcomings. Well, for now...

The support platform and the heel are made on hinges, therefore, by rotating the handle, it is necessary to control their position. On uneven surfaces, proper installation poses problems. When raising and lowering the car, you need to monitor the level of the handle, otherwise your fingers will meet the asphalt, and this is unpleasant. The maximum lifting height is 400 mm, the suspended wheel lifts off the ground by 105 mm! However, this is not all that this jack is capable of; if desired, it can be “tightened” to 420-430 mm. But we do not recommend experimenting - there is a high probability of the car falling. Already in the middle of the climb, vibrations from the rotation of the drive handle rock the car quite strongly. Another nuance - when the lift height reaches 430 mm, the rear wheel (from the side of the suspended front wheel) will lift off the ground by 50 mm. And given the poor stability of the combined jack, this is very dangerous; a gust of wind or careless installation of the wheel will cause the car to fall to the ground.

The advantages of the jack include its compactness (fits into a 13-inch spare tire) and lightness. The design is quite rigid and, if the jack is not overloaded, it will cope with its task.

PRICE: Moscow average $4.5.

The large maximum lifting height, small dimensions and weight are balanced by poor stability and an inconvenient drive handle. The jack has a carrying case, but no instructions. One of the main advantages can be considered a very low price.

Hydraulic bottle jack

In fact, the jack can lift the car by 380 mm, but it had to be installed in a place under the bottom, where the “paws” of lifts at service stations usually go. And they are in a recess, so the lifting height has decreased. We do not recommend installing a jack directly under the flange - the area of the lifting heel is the same as that of a five-ruble coin. However, even at the same time he raised the suspended wheel to the required 35 mm from the ground. Despite the miniature size of the lifting heel, the car is not in danger of falling - the jack is as stable as a tank. It is convenient and simple to use. The folding telescopic handle, approximately 310 mm long, also serves as a key to the control valve. The only requirement is that the jack must be stored and transported in a vertical position; to do this, just put it in a compact plastic case with a comfortable handle and put it in the trunk.

PRICE: Moscow average $18.5.

The disadvantages of a hydraulic jack are the need for maintenance and a large initial lifting height. But even a schoolchild can easily cope with maintenance, especially since the whole process is described in detail in the instructions in Russian. It also provides detailed explanatory diagrams, symptoms, causes and troubleshooting methods. Such a jack will fit under most domestic cars with a margin of several millimeters.

Excellent stability, comfortable handle, large load capacity (with small dimensions), convenient case - all these are the advantages of this jack.

Hydraulic rolling jack

This hydraulic rolling jack is ideal for use in garage conditions (namely, in a garage, not in a service station). Four metal wheels make it easy to move without lifting. The handle rotates 360 degrees, allowing you to operate the jack from any convenient side. The model under test has a so-called pre-lift lever, which allows you to set the lifting heel within 1-2 seconds directly to the height required to start lifting (i.e., in our case, under the bottom of the car). After this, you can begin to work with the pump plunger. The maximum lifting height can be increased by 93 mm (543 mm) by installing a special spacer (supplied) under the lifting heel. We didn’t use it, and in general we raised the car only by 410 mm, while the hanging front wheel rose by 115 mm, and the rear one almost lifted off the ground. Although here there is no need to worry about the stability of the car - it stands like a glove. The 625 mm long drive lever is equipped with an anatomical rubberized handle; it also functions as a key for the control valve. With sufficient dexterity, you can install a jack under the rear beam or axle and hang two wheels at once; fortunately, the lifting capacity of three tons allows this to be done. But this is inconvenient to do with a standard drive lever.

PRICE of a hydraulic rolling jack: average in Moscow $79.

If you like to repair your car or just try to monitor its technical condition, then this hydraulic rolling jack will be your reliable assistant. Of course, you can carry it with you in the car, but, firstly, it is quite large (in terms of the trunk), secondly, it is heavy, and thirdly, it is difficult to install it correctly on the side of the road. So on the road it’s better to use something simpler.

Bottle jack combined pneumatic/hydraulic

The ease with which the car “soared up” was simply amazing (this is easy to explain, since the pneumatic jack is designed for 12 tons, but only 1010 kg had to be lifted). But it is inconvenient to use such a jack as a road jack. Its destiny is to work in stationary conditions, where its main advantage will be revealed - the ability to use compressed air energy for lifting. You just need to connect the pneumatic jack through a special connector to the compressor and press the lever for supplying pressure to the receiver - the air will do the rest for you. In this case, you can forget about the drive handle of the hydraulic pump, especially since the shape of the control valve allows you to open and close it by hand, without a key.

PRICE of a pneumatic jack: average in Moscow $127.

Ideal for tire shops and service stations. There is no point in buying one for a car enthusiast, since in an ordinary garage it will not be possible to realize all the capabilities of the jack.

Hydraulic jacks are stationary, portable or mobile devices designed to vertically move a load resting on them. The force required for lifting is created by the action of the working fluid, which, as a rule, uses special brands of oils. The liquid exerts uniform pressure over the entire area, providing high lifting force. Thanks to this, hydraulic jacks are the most load-lifting of all devices and have many operational advantages.

Design

The main structural elements are the plunger and the working cylinder. In the small piston, through the injection system, uniform pressure is formed, which is transmitted to the large one. Due to this, the total pressure on the plunger increases and its vertical movement begins. Thus, with the application of a small force, it is possible to obtain a significant lifting force over a large area of the rod.

In its simplest form, a hydraulic jack consists of the following components:

The drive is a piston with hydraulic oil and a pressure injection system of mechanical or electrical type.
The hydraulic distribution device directs the generated force in the required direction.
Oil filter. Cleans oil from contamination to ensure uniformity of the environment.
Pressure regulation system. Includes a reset valve to return the plunger to its original position.
Pump for injecting working fluid.

The lifting capacity of the jack can range from 1.5 to 1000 tons or more, which is the best indicator among this class of devices.

Application, advantages and disadvantages

The scope of application of hydraulic jacks covers many areas of activity - from domestic use to the construction of multi-ton structures. First of all, this is a car service, where diamond-shaped and rolling jacks are widely used. This type of device is widely used in the installation and repair of industrial equipment and the installation of metal structures. Lifting jacks are also used in construction, in particular during the repair and reconstruction of buildings. Generally speaking, a hydraulic jack is used wherever it is necessary to lift or move a heavy load and secure it for a long time.

The main advantages of a hydraulic jack are:

high load capacity;
efficiency is about 80%;
low working effort;
smooth running and precise positioning, independent of the screw pitch;
high structural rigidity.

The main disadvantages are the relatively high height of the rod, which makes it difficult to work with loads with low clearance, as well as the complexity of maintenance and repair.

Device classification

There are various types of hydraulic jacks, both universal and specialized, designed to perform a narrow range of work. Of the most commonly used types, we note the following:

Basic selection rules

When choosing a hydraulic jack, you need to decide on its design depending on the purpose of the device. The maximum weight and area of the load to be lifted should be taken into account; several devices may be needed to solve the problem. The carrying capacity is selected based on the maximum weight of the cargo with a 10-15% margin in order to avoid extreme loads.

The following parameters must also be taken into account:

load lifting height;
the working height of the jack is the smallest distance from the top of the rod to the base;
composition of hydraulic oil and its resistance to high and low temperatures;
the force that must be applied to the drive;
type of drive;
pressure release speed - affects the return of the rod to the lower position. The best performance is for devices with two-way valves;
dimensions and weight of the jack.

All these parameters are in the device passport and are indicated in the manufacturers' catalogs. The variety of design solutions available on the modern market allows you to freely choose a jack that fully meets your technical and operational requirements.