How to choose a car jack

Most people know what a jack is for. With it, you can lift a load with a very significant mass to a certain height. Unlike other lifting mechanisms, the jack is always placed from below. You can’t do without it if you need to replace a wheel or do some work under the bottom of the body. Such a device must be included in the configuration of any new car, and it should always be kept in the trunk, because anything happens on the road. But the jack can break or get lost. It happens that you need a second copy or the existing device is simply inconvenient to use. The question of choosing a new jack can be confusing, especially if such a purchase is made for the first time.

Almost all existing jacks fall into three main categories - mechanical, hydraulic and pneumatic.

According to the design, five most common types of jacks can be distinguished:

1. Screw.
2. Rack and pinion.
3. Bottle.
4. Rolling.
5. Inflatable pillows (Selson air jack).

Screw and rack and pinion lifts are purely mechanical devices, while bottle and rolling lifts use hydraulics.

In most cases, the devices are operated manually - using a lever or turning a handle. But there are models that run on an electric internal combustion engine.

There is a set of varieties of screw jacks, but first of all, these are diamond-shaped models, which are most often equipped with cars, and therefore such devices are well known to many motorists.



consists of four levers and a screw connecting the side tops of the rhombus. The principle of operation is extremely simple - when the screw is rotated, the side peaks approach each other, and the top and bottom diverge, due to which the load resting on the platform in the upper part of the device is lifted.

The carrying capacity in most cases does not exceed 2 tons. For passenger cars, this is quite enough. The maximum lifting height is within 470 mm, and the minimum pickup is from 50 mm.

Such jacks are very popular among drivers due to a number of advantages:

• light weight and dimensions allow you to carry it in the trunk of any car;
• simplicity and quality of design determine a long service life (unless, of course, the product is of good quality);
• low pick-up height and a sufficiently large maximum lifting height makes such a device suitable for many car models;
• low price.

The diamond-shaped jack also has enough disadvantages:

• relatively small load capacity;
• a small area of ​​\uXNUMXb\uXNUMXbsupport and, as a result, not very good stability, therefore it is better to additionally insure the lifted load with props;
• not very convenient screw rotation mechanism;
• the need for regular cleaning and lubrication.

On sale there are also light and compact lever-screw devices.



Such jacks are very cheap, but it is better to refrain from buying them, because they have big problems with stability, especially on uneven ground. The fall of the car will not do her good, but the main thing is the risk of serious injury to a person.

, also known as a hijack (high-jack) or high-lift (high-lift), is distinguished by a low pickup height, a large lift height - up to one and a half meters - and simple controls. The lifting platform is located in the upper part of the rail, which has a number of holes for the latch along its entire length. Moving the rail with the platform is carried out using a lever. The ascent and descent modes are switched by flipping the lock lever.

There are also rack and pinion type jacks. They use a worm gear with a ratchet, and it is driven by the rotation of the handle.



Hijack has a fairly large size and weight. Such devices are especially popular among owners of SUVs, as well as those who operate agricultural machinery. A rack jack helps to pull a similar technique out of the mud. And for owners of ordinary cars, this is not the best choice.

A rack and pinion jack requires a solid base. Otherwise, it is necessary to substitute a special platform, otherwise the heel of the jack will sink into soft ground. It must be installed strictly vertically, and the ascent and descent should be carried out smoothly, making sure that there are no distortions.

A rack jack is not a very stable stand because it has a relatively small footprint. Therefore, the lifted load must be secured, for example, with a log or bricks. And in no case do not climb under the car! Of all types of jacks, rack and pinion is the most traumatic.

Hijack is not recommended to be lubricated, as dirt sticks to the oil, which can cause the mechanism to jam.

operates hydraulically. The drive pump creates oil pressure in the working cylinder, which acts on the plunger, which pushes the rod up. A rod with a special platform in the upper part presses on the load, lifting it. The presence of a valve prevents the oil from flowing back. To protect the jack from defects in the design, there is usually an additional bypass valve that opens if the permissible load is exceeded.

In addition to single rods, there are many telescopic models with two, and sometimes with three rods that extend one from the other like sections of a telescopic antenna. This allows you to increase the maximum lifting height to approximately 400…500 mm. Owners of cars with high ground clearance should pay attention, for example, to a 6-ton truck.

The pickup height of such devices starts from 90 mm (for example, model), and the load capacity can reach 50 tons or more.

Bottle jacks have many advantages that have made them widely used. Among them:

• high carrying capacity;
• smooth running;
• stop height accuracy;
• autofix;
• low labor costs;
• small size and weight allow you to carry it in the trunk.

The main disadvantages are a small lifting height, low speed, difficulties with lowering height accuracy.

Storage and transportation of hydraulic jacks should be carried out only in a vertical position to prevent leakage of the working fluid.

also applies to hydraulic lifting devices. The principle of its operation is not fundamentally different from the bottle. The payload is the same. The pickup height is mainly 130 ... 140 mm, but sometimes less than 90 mm. Lifting height 300…500 mm.

All the advantages of bottle jacks, listed above, are typical for rolling hydraulic lifts. Except for dimensions and weight. Rolling devices, with rare exceptions, are too large and heavy for permanent transportation in a passenger car.

Additional advantages of this type of jacks include maximum stability, quality, safety and ease of use. The rolling lift has a platform with wheels, due to which it drives under it in the process of lifting the load. At the same time, unlike all other types of jacks, the deviation of the device from the vertical is excluded.

However, the use of rolling jacks requires a level and firm surface free of stones and other foreign objects. They are ideal for tire shops and workshops. For a personal garage, it makes sense to purchase such a device if you often have to change wheels (for yourself, relatives, friends) or perform certain repairs. If the jack is used occasionally, it is better to buy a cheaper bottle or diamond jack.

It is also necessary to take into account the dimensions of the garage, a narrow box may be too cramped for a rolling lift. For such conditions, you need to choose a model with a swivel arm so that it can function parallel to the car and the wall. An additional convenience can be a foot pedal, which speeds up the process of lifting the load.

in fact, it is an inflatable pillow made of high-strength polymer material, which is placed under the car body. The hose is connected to the exhaust pipe, and the exhaust gases fill the air jack chamber, which inflates and raises the car. Existence of the check valve excludes arbitrary blowing off of a pillow. You can also fill the chamber with a compressor or a cylinder of compressed air. To relieve pressure, there is a valve that opens by pressing a special lever.

Filling occurs quite quickly, and physical effort is practically not required, so women will certainly appreciate this jack.

A large footprint allows the use of an air jack to pull the machine out of mud, snow or sand. A small pickup height - about 150 mm - makes it possible to use the device for cars with low ground clearance.

Many models of pneumatic jacks are equipped with a rolling device with wheels, which, firstly, increases the pickup height, and secondly, is not very convenient in snow or sand. This must be taken into account when choosing a specific model.

It is also worth paying attention to the presence of special grooves on the lifting platform of the jack, which prevent the machine from slipping during lifting or lowering. it is also worth having a metal platform under the pillow from below, this will increase the overall stability of the structure.

The service life of a pneumatic jack is determined primarily by the aging time of the chamber material, so its quality should be given special attention.

The disadvantages include not too high stability and the difficulty of maintaining a fixed height of lifting the load, since due to the compressibility of the gas, the pressure in different parts of the chamber may differ. There is also a risk that the camera will be damaged by sharp objects during use or storage.

But, perhaps, the main drawback of this type of device is a rather high price, which is why many will prefer cheaper options.

If the car has two exhaust pipes, the airbag will not inflate. You will have to use other methods of pumping.

You can choose a jack according to different criteria, but three main technical parameters are critical, which are always indicated on the body and packaging of the jack. These are the carrying capacity, the height of the pickup (hook) and the maximum lifting height.

1. The load capacity is the maximum weight that the jack is designed to lift without the risk of defects. Usually stated in tons. It should be borne in mind that the total mass of the car after it is jacked up is distributed over three wheels and a jack. To have a margin of safety, it is better to choose a device that can withstand at least half the weight of the loaded car. Excessive load capacity will not affect functionality, but the price may be higher. You should not get carried away with savings either - such devices should not be operated at the limit of their capabilities.
   
   The passport weight of cars rarely exceeds one and a half tons, SUVs can weigh 2 ... 3 tons.
2. Pickup height. This is the minimum possible distance between the base from below and the jack support platform from above. This parameter determines whether it will be possible to slip the jack under a specific car with a certain clearance. In this case, it is necessary to take into account the possible situation with a flat tire, when the real ground clearance is less than the passport one. Completely let the air out of the tire and measure the resulting clearance - the height of the jack should fit into the obtained value. Excess stock is useless here, since this parameter is related to the maximum lift height that should be enough for the wheel to come off the ground.
   
   If you have a car with low ground clearance, you should pay attention to the so-called. hook models. They have a pickup height of 20 ... 40 mm.
3. The maximum lift height is the distance from the jacking point that the vehicle can be raised. It should be sufficient to hang the wheel.
4. Weight and dimensions. They are important for a device that will always be in the car.
5. The force required to be applied to a lever or operating handle. In other words, how much will you have to sweat to lift the load.
6. The presence of a rubber gasket is required if the machine does not have special places for installing a lift.

Having bought a jack, do not rush to put it in the trunk. It is better to test it right away and make sure that it is serviceable, reliable and will not let you down when the need arises for its possible use.