All about screw jacks

A screw jack is one of the main tools that even a novice motorist must have in the kit. With the help of a jack, you can quickly and efficiently change a wheel, easily raise the car for further maintenance. The tool is compact and not particularly heavy, which reduces the cost. There are many models on the market today, each motorist will be able to choose something that is most suitable for himself, or you can assemble the necessary copy with your own hands.

The screw jack is a car lift designed mainly for passenger cars. It is compact, stable and has a number of features:

• the design provides for a plane that, when lifted, makes the load stable and reduces the risk of emergencies during repairs;
• the jack can last much longer than the minimum period, subject to the recommended level of loads;
• the tool is resistant to adverse environmental influences.

The design of the jack is simple, its main purpose is to lift and fix the load in one position at a strictly defined height. The tool works on the basis of elementary laws of physics, the torque creates a translational motion that allows you to lift and fix the load. The main parts in the design are: nut, screw and gearbox.

There is also a hydraulic jack with its own characteristics: it is more reliable due to the presence of a mechanical brake in the design... The gearbox transmits torque to the nut, thereby lifting. And at the right time, when the maximum height level is reached, the braking mechanism is triggered, and the position of the car is fixed.

A modernized manual jack has also appeared on the market, the design of which provides for the presence of special lifting rollers. This makes the structure more reliable as the frictional force is reduced. As a result, the tool lasts much longer and more efficiently than its counterparts.

There are various types of screw jacks with a worm gear, but the main task of each tool remains the same - lifting and fixing the load in a certain position during the repair. The presence of a screw helps to lift the car without additional devices in the form of ropes or chains.

Most often, in the conditions of Russian roads, a vertical lever-screw jack is used. Vehicle weight can be up to one ton.

Levers and a screw are the main ones in the design. The angle between the levers is changed using a special handle. Such tools are small-sized, have a small height and a working stroke. The structure is rigid, the support is wide. Their plus lies in the simplicity and versatility when carrying out repair work.

This type of long stroke design can have multiple screws, which increases the lifting capacity. Additionally, the mechanism has a rigid body and thread, one screw is screwed into the other, which guarantees a certain lifting height. The only drawback of such structures is their weight and low lifting height (with one screw).

The type of jacks working due to the presence of a cylinder and a pivot point, which guarantees the fixation of the load in a given position. Sometimes in such models, a spacer mechanism is provided, which increases the performance. In the cylinder, a special piston occupies a key place, which provides a connection with the rest of the mechanism. If the design is hydraulic, then the presence of a pump with a liquid is also provided. The difference in liquid level is what gives the work efficiency.

In this case, the piston performs the function of pumping by means of valves. One of them is located near the cylinder and prevents oil from entering the key parts of the mechanism. The position of the liquid in the reservoir is maintained under pressure. The pressure when lowering the load decreases evenly, and the working fluid returns to the reservoir during operation.

The myth that jacks are used only to change wheels has long ceased to hold up to scrutiny. On the road, the tool is used precisely for this, but this is far from its only purpose. It all depends on the type of tool and design features.

The cable jack is designed for lifting drums. It is used as a pay-off device in the process of cable rewinding and laying. Using it, it is much easier to rewind or rewind the cable completely.

The jack axis is threaded through the central hole of the drum and is fixed between the bushings and the cones. The structure additionally receives protection in the form of frames and, only after that, it is the turn of work for the lifting mechanism. Lift in conventional models can be carried out up to 100 mm. The design of cable jacks can be screw, lever or hydraulic. It all depends on what kind of tool the user needs to work.

Industrial jacks are lifting devices of a completely different class, designed for professional maintenance of a wide range of vehicles. Their designs can be with ratchet or screws, but the main thing that distinguishes them is their high technical characteristics.

For example, mechanical jacks of industrial type have a lifting capacity of more than 20 tons. And the performance of hydraulic models of the same line can reach up to 200 tons. All this is combined with strength and a fixed lifting height. It is clear that this option is not suitable for a home workshop.

Despite their name, such jacks are quite capable of autonomous operation; they do not have to be constantly connected to the outlet. The on-board electrical system will also do, the jack will work even if the engine is out of order. The work algorithm is quite simple:

• the device connects to the network;
• the required height is created using the remote control;
• the jack lifts the load on its own.

If we talk about other types of tools, then a mini plastic jack is more suitable for self-production, this is the option that is completed today for most Russian-made cars. Typically, these devices are classified as rack jacks and have a simple threaded screw design. There are two screws in the design. It is with their help that the car is lifted, and then the load is securely fixed. The ease of use of such a design is individual for everyone, many drivers find it easier and more accustomed to resort to using hydraulic models. But the mechanical model is easier to transport.

When buying a jack for a car, you should consider not only the best models and reviews, but also the main parameters. On the modern market, there are specimens with a carrying capacity of 2-3 tons and up to 16-20 tons. More powerful models also have a higher rate. For example, you can purchase a jack with a lifting capacity of 50 to 100 tons inclusive. Such tools have a narrower range of uses, but they are more resistant to negative external influences throughout their entire service life.

Different jacks have a different design, the threaded jack will differ accordingly in the thread in the key nodes, and in the design of the rhombic jack there will be several levers connected by hinges. The hinges are attached to a support or platform that serves as the base for the entire mechanism. Outwardly, all this very much resembles a rhombus, hence the instrument got its name.

In addition to the main characteristics, you should pay attention to the brand and dimensions of the tool. Among the known models with a minimum carrying capacity, we will consider a number of products.

• "Zubr 43040-1" - suitable for monophonic cargo. The lift height is 383 millimeters, which is sufficient for most passenger cars.

• STVOL SDR2370 already lifts 2 tons, but the maximum height is 13 cm less than that of the previous model. Small-sized cars of the middle class can easily be serviced with this tool.

• Inforce T10202 also has a lifting capacity of 2 tons, but the lifting height is 395 mm.

Depending on the intended goals, the criteria for choosing jacks for cars also change. A novice user needs to immediately decide whether a manual jack or an electric jack is needed for work. In both cases, the weight of the vehicle and the level of load that the device must withstand during operation are taken into account.

In addition, there are a number of basic characteristics that you should pay attention to when buying a jack.

1. Carrying capacity - a parameter that is taken into account depending on the brand of the user's car. For universal use in this case, the rule "the more the better".
2. Lifting height - similar to the first case. But here it is important to take into account the design features of the car, since its bottom can be equipped with grooves and cells.

The electromechanical jack, which combines the advantages of several models, is especially popular on the market. Sometimes such a tool or its simple mechanical counterpart comes with the machine. When buying, special attention should be paid to documentation, power and weight indicators. This will help you select the right lifting tool.

How to "jack" correctly is one of the first questions that novice motorists invariably ask. Problems with the wheel can overtake everyone at the most unexpected moments, so it is worthwhile to figure out the algorithm of the main actions in advance.

The jack is a tool not only for lifting a log house, but also for completely changing wheels. But before replacing them, it is imperative to unload the car, otherwise this can lead to overweight and damage to the tool. The machine must be stopped on a level surface and the wheels must be blocked. When repairing the front wheels, the rear wheels must be locked and vice versa.

Install the jack carefully. Usually the places of "connection" are marked with a stamp, so it is difficult to make a mistake here. The side pads are removed before this. It is possible to work with the jack only in a strictly vertical position relative to the fulcrum. The machine must be lifted evenly, without unnecessary jerking. Then block and make sure that the vehicle is firmly in place.

Then it remains only to replace the wheel and lower the car in the reverse order. If you follow the instructions, then even the most inexperienced user can handle it.

For an overview of the ZUBR 43040-2 screw jack, see the following video.