Since ancient times, people have been faced with the problems of lifting a large load to a height, for this, many people were usually involved, and bulky structures were erected, which did not always have super strength, and therefore often broke, provoking human casualties. A way out of the situation appeared with the invention of such a machine as a hydraulic jack, which is still widely used today. Such an installation, unlike winches, has greater reliability and is capable of lifting large loads at lower costs..
Today it is impossible to imagine carrying out repair work on a car, whether it is a suspension repair or a wheel change, without the use of jacks – special mechanisms that are designed to lift a heavy load and fix it at the required height. The most effective are hydraulic jacks, where the working force is created using hydraulic oil and a piston..
The first mechanical jacks appeared in antiquity. And the idea of creating a hydraulic jack scheme specifically for a car arose unintentionally. Repairman Peter Lunati spied on this idea in a hairdresser, surprised how easy it is for a haircutter to fix a hydraulic chair at a certain height. In 1925, a sophisticated platform lift with a hydraulic strut for a car was made.
Hydraulic jacks differ in carrying capacity, which ranges from one to several hundred tons, which allows them to be used in the repair of trucks and other heavy equipment.
The weights used are machine bodies or flooring, foundation slabs and columns. Depending on the purpose of application, such equipment has different dimensions and design..
A hydraulic jack is used for moving, lifting and securing loads. The device is used in the field of general locksmith and tire fitting, and is also indispensable when preparing a car for a long trip to create balancing: the wheel is removed with a jack and balanced using special equipment.
Modern hydraulic jacks are widely used not only in service stations and car services. They are successfully used in oil refineries, power plants and other industrial complexes. The highest level of productivity and ease of operation allowed this technology to be introduced into the domestic environment, so many owners have a hydraulic jack in their garage..
This equipment is capable of working in horizontal and vertical planes, therefore it is widely used at construction and assembly sites and for tensioning reinforcing structures made of pre-stressed reinforced concrete..
The main bearing elements of a hydraulic jack are the body, the working fluid, usually oil, and the retractable piston. The hydraulic jack has a long or short body, which is made of hardened steel. The body performs the following functions: it acts as a guide cylinder for the piston and is a reservoir for working oil.
A screw with a lifting heel is screwed into the plunger, unscrewing the screw, therefore, if necessary, it is possible to increase the maximum lift height. This type of jack is equipped with a hydraulic pump with manual, foot or air drive. The hydraulic jack device is equipped with safety valves and other devices to create a long trouble-free operation.
The lifting mechanism and the retractable hydraulic cylinder, which is lifted up by a special platform, are located in the holes of the body. The descent takes place by turning the T-shaped handle. The equipment has polyamide wheels that provide the jack with maneuverability. Long range body is mainly used for working with buses and heavy vehicles.
Any hydraulic jack works according to the principles of communicating vessels using a liquid. Before starting work, place the jack on a flat solid surface under the car and press the lever with the valve closed until the machine rises to the required height. The descent of the car is carried out by smoothly opening the valve of the apparatus counterclockwise.
The working hydraulic oil is pumped by the drive pump using the lever. Liquid enters the cylinder through the valve and squeezes it out. Backflow of liquid will be prevented by valves – delivery and suction. To lower the jack back, it is necessary to open the valve on the pump, then the oil will flow from the cylinder back to the pump.
The presence of a thread on the body of the jack, which is protected by a dust cover, threads on the stem and threaded holes in the base guarantee unlimited use and operation of hydraulic jacks for crimping, clamping and bending. The high strength support, which is made of hardened steel and mounted on the stem, is able to protect the hydraulic jack from damage. The grooved support surface prevents the sliding of weights. The force of the hydraulic jacks is regulated by the built-in pressure gauge.
Hydraulic jacks are among the most unpretentious for all their power. An important feature of hydraulics is an incompressible working material. Hence – the smoothness of lowering and lifting, fixing the load at the desired height and braking accuracy. Hydraulic jacks demonstrate a high level of efficiency – up to 80% and significant lifting capacity – up to 200 tons with low effort due to the large gear ratio between the cross-sectional surfaces of the pump plunger and cylinder.
But hydraulic jacks have a much higher initial lift than mechanical models. Another difficulty is the impossibility of precise control of the lowering height. To maintain the jack in working order, it is necessary to constantly monitor the oil level, control the tightness of valves and oil seals. Such jacks can be transported and stored exclusively in an upright position, since otherwise the liquid may leak out of the tank..
The disadvantages of hydraulic jacks stem from the advantages. They are relatively slow – one pump cycle corresponds to a not too high lift. Disadvantages include large weight and size, high cost of hydraulic jacks, and short travel for single-plunger models. In addition, these tools often have more serious breakdowns and malfunctions than mechanical devices..
There are several types of hydraulic jacks..
The design of the bottle (vertical) hydraulic jack is the simplest. The scope of use of such jacks is quite wide due to the large range of lifting weights – from 2 to 100 tons. “Bottles” are used in trucks. In addition to the main advantages of a hydraulic jack, vertical models have several more – versatility of use, compactness and a large support area.
There are single-rod and double-rod bottle jacks. The hydraulic single-stem device is distinguished by its simplicity of design and ease of operation, which expands the scope of its use and allows you to perform work of any complexity: installation and dismantling in mechanical engineering, construction, repair of cars, railway car wheels, use of a press, pipe bender, pipe cutter and similar tools as a power unit.
The telescopic double-rod jack has a similar design to the bottle apparatus, the principle of operation of the bottle-type hydraulic jack is based on the use of several working rods. The piston is at the base of the telescopic jack. It can be applied horizontally and vertically. It is compact and fits most machines. Lifting is done using a lifting arm driven by a hydraulic cylinder.
The rolling jack works on the same principle as the bottle jack, but with the difference that the axis of the working cylinder is not located in the vertical axis, moreover, the piston is not directly aligned with the pick-up and the lifting lever is activated. This unit is called trolley because it is a cart on wheels that can roll on a flat surface. When lifting the pick-up and the lever, the jack “rolls up” or moves under the load.
Such a jack is set in motion by the same swing of the lever as in the bottle models, it is lowered in the same way – by turning the valve screw. If it is necessary to lower the load down, it is necessary to put the tubular handle on the valve screw, after which the partition will go into the groove of this screw. By rotating the handle around its axis, the user also rotates the screw, respectively, relieving the pressure in the working cylinder and lowering the weight to the required height.
Most often, a rolling jack can be found at a tire fitting station, because it is ideal for lifting one side of the machine, it is fast enough to work and install. The disadvantages of this design stem from the name – a rolling jack needs a flat solid surface, concrete or asphalt to work. In addition, the substantial size and weight make it difficult to transport the unit in a car..
Rolling jacks are classified by purpose, as in the photo of hydraulic jacks:
- For personal use by motorists, carrying capacity up to 3 tons;
- For car services and tire shops, with a carrying capacity of up to 4 tons and with the presence of pre-lift pedals to instantly reach the required pickup height;
- For servicing heavy machines and special vehicles (forklift trucks), with a lifting capacity of up to 20 tons and with the presence of pre-lift pedals and a sliding traverse, which is designed to lift one side of the machine.
The transmission jacks are equipped with a special swing frame. This is where the smoothness and precision of the hydraulic jacks are shown in all their glory. The gearbox of the car, which is mounted or dismantled, can be precisely fixed in a horizontal or vertical plane in the desired position.
Two-level jacks are needed mainly in car services, where they work with different cars. The features of this device include two lifting platforms. The drawing of a two-level hydraulic jack as a whole is a hybrid of a rolling and bottle jack. To be more precise, a two-level jack is used at a height of 65 – 375 millimeters from the ground as a rolling jack and at a height of 375 – 687 millimeters as a telescopic one. When working with the lifting mechanism, a hand lever and a foot pedal are used..
The pneumohydraulic jack combines hydraulics and pneumatics. It can be manufactured in a rolling solution and has a lifting capacity of 2 – 80 tons. The initial pick-up height is low. It is used exclusively as equipment for a car service.
Low-grip hooking jacks are widely used wherever a low pick-up height is needed: for installing and dismantling various equipment, for lifting the track on the railway, as well as in auto repair shops. It is such a low pick-up height, which is from 15 millimeters, with the possibility of its step-by-step adjustment, which is very convenient when assembling mechanisms and acts as a hallmark of the hook jack. But at the heart of this jack is a simple bottle-type device.
The hydraulic rhombus jack is mainly required for lifting machines when repairing. It is characterized by high reliability when compared with a screw relative, and is practically not inferior to it in ease of use..
In a diamond jack, four levers act as load-bearing elements, which are connected by hinges. The scheme of operation of a hydraulic jack and lifting of loads is based on changing the angles between the levers. The advantages of rhombus jacks include small dimensions, which provides convenient storage, transportation and, at the same time, a significant supporting surface and structural rigidity. Relatively low pickup height.
When a car enthusiast independently maintains his entire fleet, one of the most essential tools is a press. We suggest you make a press from a hydraulic jack with your own hands, which will become a reliable companion when performing a whole list of works. With its help, you can punch holes in different materials, press in inserts and bushings, press metal waste.
Assembling a hydraulic press is not that difficult. For this you need a welding machine with the required number of welding electrodes, a hand saw, an angle grinder with a disc for metal, a steel thick-walled profile to complete the design of the press. The functions of the power unit, providing the required working pressure, are performed by a hydraulic jack.
The first unit of the hydraulic press is the support platform for the jack. Since the resulting pressure will be proportional to the pressure applied to the base and the upper working nodes, the strength of the base should be maximized. This can be achieved by making several stiffeners on the basis. To make the base, take a steel square or rectangular profile that has a size of 40 by 50 or 50 by 50 millimeters and cut 4 parts about 250-300 millimeters long using the above tools.
After that, it is necessary to lay these parts with the side walls to each other and weld the joint seams at the top and bottom to increase the rigidity of the press base. To ensure high stability of the hydraulic jack, weld a steel plate to the resulting structure, the sheet of which has a thickness of 8 -12 millimeters and a size of 250 by 200 millimeters.
The next step in making a homemade press from a jack is the production of a stop and racks. To do this, it is necessary to saw off 2 parts from a profiled thick-walled rectangular or square pipe of the required length. To calculate it, you need to clarify the maximum stroke of the rod according to the attached instructions for the jack and add the height of the hydraulic jack itself and the support platform to the resulting size.
Make an emphasis from the material that the racks are made of. The length of this part must be equal to the width of the support platform in order to maintain the overall geometry of the structure. Connect the stop and the resulting racks to each other with a weld and weld the U-shaped structure to the base.
When performing such assembly operations, it is recommended to use a simple device that ensures the perpendicularity of the parts to be joined. On a steel sheet that has a thickness of at least 10 millimeters, two trims of a steel corner 40 by 40 millimeters should be welded at an angle of 90 degrees. Place the parts to be connected in the future in this device and weld.
This way you can achieve the desired connection angle. For additional convenience, this impromptu square can be additionally equipped with clamping devices that fix the parts to be joined and prevent the connection angle from breaking through thermal changes during welding in metal.
The next mandatory element of our press is a removable stop, which is able to move along the guides and transfer pressure from the central working rod of the hydraulic jack to the workpiece. Prepare for its manufacture several pieces of steel strip, which has a thickness of about 1 centimeter. Make the length of the parts less than the resulting distance between the posts. Connect the resulting parts in several places by welding on both sides.
To ensure a quick replacement of this part when performing any hydraulic work and to fix the element when moving on vertical racks, it is necessary to drill two through holes in the resulting block of steel strips and saw off two plates, their length should be 100 millimeters longer than the block length. Also drill two holes in the plates, which are tolerable with the holes in the block..
When installing the block on the press frame from a hydraulic jack with your own hands, select two bolts of the required length with nuts and washers and connect the resulting plates to the block so that they are located from the racks on both sides. If the need arises to achieve a smaller free stroke of the hydraulic jack piston, it is possible to reduce the space between the moving stop and the upper beam of the structure with the additional installation of an intermediate square profile.
For this, cut off a piece of a square profile, which has a length that is equal to the distance between the posts, and at an equal distance of welds, attach it. This will significantly reduce the working distance of the hydraulic press and reduce the time spent on performing certain types of work..
To further reduce the stroke of the hydraulic jack working rod, additional replaceable inserts can be used, which are made of solid or hollow steel profiles or replaceable anvils. To create them, you should saw off several parts of different thicknesses and additionally mark them for quick and careful selection of the desired element.
Hydraulic jacks periodically need maintenance, therefore, it is necessary to add liquid to the working cylinder, which flows out during operation through the oil seals and various seals. In addition to oil leakage, jack malfunctions consist in jamming when lifting a load to a certain height, the impossibility of lowering the jack after lifting, or the inability to lift even a light load.
To repair and test a hydraulic jack at home, you should buy the necessary repair kit for the equipment. Disassemble the unit first before carrying out repairs. An extension to the wrenches may be required to provide more force and more leverage. Be sure to prepare a container for draining the old oil and prepare a new working fluid.
After that, the pistons should be removed and checked for corrosion. It is customary to remove all dirt and corrosion. Check for a bent stem. If deformation takes place, then it is unlikely that it will be possible to make it even again and you can no longer repair anything..
Check the oil bypass valve. For this, the valve is unscrewed and checked for deformation or ingress of dirt into the valve. If the valve is defective due to mechanical deformation, then it should simply be replaced. In addition, it can simply get dirty, and the ball will sit loosely in its saddle. This is the reason for the transmission of the working fluid..
Drain the old oil completely. This procedure is quite simple, although it takes a long time as the oil flows from one to another cylinder. The liquid is drained by pumping the system, moving the lever up and down. Rinse all parts thoroughly to remove dirt and oil residues. Replace all cuffs and gaskets completely.
Another reason for hydraulic jack failure is dirt that has entered the working cavity. To remove it from there, it is necessary to unscrew the head of the case, pour kerosene into its base and pump the jack with the unscrewed locking needle. At the end of the operation, kerosene should be removed and clean oil should be poured into the working cavity..
Air bubbles accumulate in the working cavity of the jack during long-term operation, significantly reducing its efficiency. This is usually caused by air that has entered the hydraulic system due to a lack of working oil. You can eliminate this problem as follows.
First, open the oil tank cap and bypass valve, and then quickly bleed the hydraulic press pump several times. In this way, air will be forced out of the working cavity into the oil container. You can then close the bypass valve and the hole leading to the oil tank. If you did everything correctly, then the air will be removed, and the jack will work in normal mode again..
If your attempt is unsuccessful, repeat all of the above steps. However, this method is not the only one for removing air from the working cavity. It is not difficult to determine the presence of air in the working cavity: the jack does not work at all, or the load is lifted slowly.
First of all, unscrew the shut-off needle one and a half to two turns, then lift the plunger by hand by the screw to the extreme upper point and release it so that it is again in the lower position. Repeat these steps twice or three times. To prevent a similar problem from arising in the future, it is worth periodically checking the oil level in the hydraulic jack and, if there is a shortage of it, add working fluid..
Thus, you familiarized yourself with the design of a hydraulic jack, studied its advantages and disadvantages, figured out the classification of such equipment and understood how a hydraulic jack works. Now you can start assembling the device yourself. And don’t forget about periodic maintenance and adding operating oil..