In detail: do-it-yourself repair of a Chinese hydraulic jack from a real master for the site my.housecope.com.
Every self-respecting motorist knows at least a dozen ways to use a good jack. And the fact that with its help the wheels are changed is understandable. One of the most reliable jack designs remains hydraulic, and it became available to a wide mass of motorists not so long ago. The fact is that the industry previously produced only hydraulic jacks of large carrying capacity, which could only be used stationary or transported in trucks. For light vehicles, these mechanisms were simply unsuitable. Large weight, dimensions and large initial lifting level made their use possible only in boxes and at special service stations.
Now the situation has changed dramatically and jacks with hydraulics have become much more, and they have become different, both structurally, and in size and carrying capacity. Now everyone can choose a jack in their weight category and in accordance with their needs. Now you do not need to buy a huge five-ton mechanism in order to raise the front end of a small Daewoo. Such small models are compact, lightweight, fit in the trunk and can serve as a small press and a whole bunch of work.
There are many types of hydraulic jacks, but if our beloved and the only one broke down, we absolutely don't care what you can buy in stores:
rolling hydraulic jack;
bottle;
single-plunger or double-plunger;
with electric or manual drive.
The principle of operation is the same for everyone and do-it-yourself repair of a hydraulic jack should be carried out on the basis of knowledge of its fundamental design, regardless of the brand and carrying capacity.
Video (click to play).
Any hydraulic jack has a working fluid, oil, which has a very low compression ratio. For uninterrupted and stable operation of the hydraulic mechanism, periodic fluid changes and system cleaning are required.
Depending on the class of lifting capacity, the jack can have a two- or three-stage telescopic stem design. Jacks are often equipped with threaded extensions that allow the initial lifting height to be adjusted.
The working hydraulic part consists of:
a cylinder with a polished surface in which the working fluid is located;
piston with O-rings;
power rod, which can be telescopic and have several steps;
a plunger pump supplying liquid to the sub-piston space;
bypass valve and needle systems, they create and maintain pressure in the working chamber;
filler hole;
bleed valve;
cuffs and seals.
It is quite simple to deal with all this economy and we will start with the reasons for the malfunction in the hydraulic part of the device.
The first reason for the failure of hydraulics is damage to the mirrors of the plunger and the working cylinder. In this case, the device does not hold pressure, the oil easily flows from the working chamber to the above-piston one, therefore such a jack simply either does not work or does not hold the load poorly. Damage to mirrors is due to the owner's negligence. Firstly, the jack cannot be stored and transported horizontally if the manufacturer has not foreseen this possibility. The result is a leaked working fluid, airing of the hydraulic system, and where there is air, there is corrosion.
Secondly, when corrosion appears on the mirrors of the working surfaces of the jack, the cuffs and seals instantly wear out - the rubber is not iron. As a result of this story, even more foreign debris, wear products of cuffs, corrosion products appear in the oil, which leads to clogging of the oil passages and valves. Therefore, it is necessary to change the fluid and flush the hydraulic system.
Repair of hydraulics is reduced to draining the old fluid, completely disassembling the jack and replacing the seals and cuffs. There is nothing complicated about this, since the jack does not require any complicated adjustments, only diagnostics, maintenance and, if necessary, replacement. And all sealing elements and cuffs are subject to replacement. We strongly recommend that you do not go to the workshops and, moreover, do not look for original seals - this is practically useless. The fact is that almost all sizes of hydraulic jacks, more precisely, of its seals, are standard and can be sold at any point dealing with consumables for tractor and automotive hydraulics. It will be three times cheaper, the main thing is to measure rubber parts or take them with you.
A sliding hydraulic jack differs from a bottle jack only in a more complex mechanical part and hydraulics, which is designed to work in a horizontal position. If it is completely disassembled, the hydraulic part will have very little change compared to the vertical jack. The mechanical part is repaired as problems appear, and they can be expressed in wear of the lever-lifting system, wear of the hinges and joints, as well as in the adjustments of the support mechanism.
After the jack is repaired and assembled, it is necessary to expel air from the system and pump it with new fluid. The liquid is poured to the eyeballs, after which the structure is pumped several times until the jack stably holds the rated load. The system is then checked for fluid leaks and the jack is ready for use. Lift weights carefully, and good luck to everyone!
A jack is a special device with which a heavy load is lifted and fixed at the required height. This mechanism is simply irreplaceable when performing any car repair, for example, when changing a wheel.
Trolley hydraulic jack.
The most convenient and effective for work are hydraulic jacks, the working force of which is achieved using hydraulic oil and a piston. Assembly and repair of such a device can be done by hand.
The rolling jack belongs to the category of hydraulic ones, only it has a slightly different design. On its body, made of metal, two pairs of wheels are installed. In the holes located on it, a lifting mechanism and a hydraulic cylinder are mounted, which, when extended in the horizontal direction, lifts the platform. The device itself gradually raises the car to the desired height, while it rolls under it.
The jack is set in motion by swinging the lever and lowered by turning the valve screw. During the process of lowering the load, a tubular handle is pushed onto the valve screw, and after that the baffle enters its groove. When the handle rotates around its axis, the screw itself rotates accordingly. In this case, the pressure in the working cylinder is released, and the load is lowered to the desired height.
In order for the jack to serve for a long time, it is necessary to monitor the presence of oil in it and the condition of the oil seal and valves.
There are sliding hydraulic jacks used for personal purposes for vehicles with a weight category up to 3000 kg. Most often, such a device, equipped with the pedals necessary for preliminary lifting, is used in car services and tire stations.It can lift loads up to 4000 kg, doing the job quickly enough.
Jacks, which lift loads up to 20 tons and are equipped with pre-lifting pedals, as well as a sliding traverse, are designed to serve heavy machines and special vehicles. This mechanism also has its drawbacks, which include volumetric size and heavy weight, which makes it difficult to move it in a car. It requires a flat, horizontal surface such as asphalt or concrete to work.
wrench;
container for draining oil;
kerosene;
butter.
During the operation of the jack, its breakage may occur. The malfunctions of this device include oil leakage, jamming when lifting to a height, or, conversely, its refusal to descend. In any case, it should be repaired.
If the cause of the breakdown is oil leakage, then first you need to disassemble the device. Then the pistons are removed from it and checked for corrosion. After that, all dirt and the resulting corrosion are carefully removed. Next, the stock is checked. In the event that it is bent and deformed, the repair of the jack can be considered impractical.
The principle of operation of a hydraulic rolling jack.
When repairing a valve that allows oil to pass through, you need to unscrew it and check if dirt has got inside and if it has been deformed. In the event that it has undergone mechanical deformation, the valve should be replaced. If it gets dirty, then the working fluid will flow due to the fact that the ball has ceased to sit tightly in the seat. Therefore, first, the old working fluid (oil) is drained into the prepared container, while pumping the system with the lever, raising and lowering it.
Then all parts are thoroughly rinsed from trapped dirt, as well as from the remnants of old oil. In this case, it is imperative to replace all the cuffs, as well as the gaskets. If the dirt gets directly into the working cavity, then to remove it, you will need to unscrew the head of the case.
After that, kerosene is poured into its base, and the jack is pumped. In this case, the shut-off needle must be unscrewed. At the end, the kerosene is removed, and a clean working fluid is poured into the working cavity.
The efficiency of the jack may decrease due to the accumulation of air bubbles in its working cavity, which get there due to a lack of oil.
Repair in this case is carried out as follows. First you need to open the plug at the oil tank and the bypass valve. Then, at a fast pace, the pump of the hydraulic press is pumped several times so that the air from the working cavity moves into the container in which the oil is located. The oil tank opening and the bypass valve are then closed. If the whole process is done correctly, the jack will start working normally. With the remaining air in it, all actions are repeated again.
If this device does not work or raises the load very slowly, then air can be removed from the working cavity in another way. To do this, the shut-off needle is turned one and a half or two turns. Then, with the help of a hand, the plunger rises by the screw, reaching the extreme upper point.
