The hydraulic jack doesn’t lift under load

Why does the jack not lift all the way up?

Sturdy and simple helper in lifting heavy loads, it has a reliable construction, which serves as a guarantee of safe work. The high criterion of durability is considered to be the main indicator of the jack efficiency, however, even this level, does not exclude the possibility of the device breakage. In this topic, we have listed all the possible causes of failure of hydraulic jacks of all kinds, parsed them and compiled step-by-step instructions on how to fix those or other malfunctions.

To determine the exact cause of the failure and its subsequent elimination, it is necessary to have a clear understanding of the principle of operation of the device. Fortunately, hydraulic jacks are constructed quite simply and most of their faults can be repaired on their own. Contact the service may be necessary in cases of serious defects or a complete lack of desire to read the repair manual. The basics of understanding the operation of the device should be started by taking apart the main components of its mechanism.

Before describing the functional elements, it’s worth noting that hydraulic jacks have several subtypes and are divided into jacks, bottle jacks and lozenges. To the classic type of hydraulic lifting mechanism, the bottle type, which includes devices with telescopic, hollow, hitch and standard rod is the closest. To form a proper basic idea, let’s take apart the original model without additional modifications. So, the hydraulic bottle jack, consists of the following components:

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  • Casing base. Supporting pad for mounting the device on a flat surface.
  • Housing. The outside of the hydraulic jack and, by extension, the oil reservoir.
  • Plunger cylinder. Sealed chamber where the fluid pressure exerted by the ram is created.
  • Working plunger. Extendable element with a stop at the end.
  • Port for filling up the oil. Located in the upper, lateral part of the body of the device.
  • Screw. Retractable element for increasing the jack lift height. Screwed into plunger.
  • Body head. The threaded joint that locks the body in relation to the cylinder.
  • O-ring. Seals the oil reservoir, preventing fluid leakage.
  • Screw nut. Upper part of the housing head with six faces for easy unscrewing.
  • Lug. Handy element for manual jack transport. Not found on all models.
  • Screw head. The end of the rod resting on the weight.
  • Lever. Removable hand pump element that multiplies impact force. In most cases, includes a special groove for unscrewing the shutoff valve (more about it later).
  • Displacement plunger. Main element of the pump, driven by the lever. Pumps fluid from one reservoir to another.
  • Pump cylinder. Pressure chamber and transfer path between reservoirs.
  • Shutoff valve. Used for connecting / isolating the oil reservoir with the ram cylinder.
  • Suction valve. Controls fluid movement within the unit, allowing it to flow in one direction only (suction to pump cylinder only).
  • Relief valve. Opposite of suction. Allows pump plunger to squeeze oil through, but does not let it back out.

The essence of the action of the device is based on pumping liquid from the oil reservoir into the cylinder with a plunger. When the lever is raised, the oil portion is sucked into the pump cylinder, and when lowered, it is squeezed into the main cylinder of the elevator. By doing this, pressure is generated in the main compartment, pushing out the piston.

Most importantly prevents air from entering the compartment, which can reduce stability and overall efficiency. It is for this reason that the hydraulic bottle jack does not work horizontally. However, even in this type of device there are models that allow lifting in different positions.

Repair and pumping jack with his hands

As a rule, all hydraulic jacks are a non-disassembled construction, which cannot be repaired. However, in all cases it is possible to pump. When considering how to pump the hydraulic jack, let us note the following points:

  • A special valve is opened and the plug is removed from the oil reservoir. This is required to drain the old liquid and pour in the new liquid during pumping.
  • Often the jack is pumped because of the presence of many contaminants in the working part of the device.

It is recommended to pump the bottle-type hydraulic jack in accordance with the recommendations placed by the manufacturer. Removal of the waste is carried out until there is no air in the working cylinder. This is due to the fact that bubbles significantly reduce the effectiveness of the device, since the gas has a lower density.

The main causes of malfunction of the hydraulic jack and ways to fix them

One of the most common causes of jack failure could be oil leakage. As a result, air enters the working chamber, as a consequence, the lifting mechanism does not work to its full capacity or ceases to function.

It is possible to avoid this problem by periodical hydraulic jack maintenance, which consists in checking liquid quantity and refilling of working cylinder if it is necessary. Reduced oil level in the system may be due to natural attrition, but also due to damaged or faulty seals and packings. In this case, the usual topping up the oil will not solve the problem and the damaged seals and gaskets must be replaced.

Due to a lack of working fluid in the system, air takes its place. you can guess that by the reduced efficiency of the jack. You can get rid of this problem by pumping. To do this, open the oil tank plug and bypass valve and pump the hydraulic pump. If the fault is in this, then if this work is done correctly, the jack will be back in working order. But if this does not help, then either the cause of the malfunction is different, or a more serious repair will be needed. Sometimes the problem can be solved by unscrewing the locking needle two turns, simultaneously raising the piston to the upper point and then releasing it to reach the lower point. This action should be repeated 2-4 times.

It is not uncommon for corrosion to attack the retractable pistons (rods or rams) and the inside of the jack to be the cause of malfunctioning of the hydraulic jack. But in order to find out the cause, you need to disassemble the machine. For this you can go to a service shop or perform the work yourself. You will need a set of wrenches, a repair kit, a container to drain the old oil and a canister with new oil to pour into the system after the repair.

The bent rod also often becomes the reason of jack failure, in this case, if it is provided by design features of the model, it can be replaced for a new one, but often it means that the jack cannot be repaired even in a service shop.

Sometimes dirt gets into the working chamber, which can also cause the jack to malfunction.

It is possible to remove the dirt by washing it with kerosene. The bypass valve is also quite often the culprit. It may have some deformation, or dirt may get into it, which causes the ball not to be seated tightly in the seat and, consequently, fluid leakage. This problem is mostly solved radically. by replacing the bypass valve.

Design and principle of operation

The structure of hydraulic jacks is almost similar to that of jacks, as well as of bottle jacks. The main parts of the roll-ups:

When you lift the handle up the shutoff valve is triggered, the oil flows into the chamber through the suction valve. The piston is raised by pumping oil from the reservoir into the operating cylinder cavity. Next, to lower the piston with the rod, the bypass valve opens, then the pressure of the load will lower the piston.

The main faults and their causes

Among all the reasons why a hydraulic jack jack does not work, bottle jack or lozenge jack, there are 3 main options: system clogging, valve failure or rod damage. The most common malfunctions associated with a decrease in efficiency or complete failure of the system are based on these 3 pillars. For clarity, let’s look at each case in more detail.

System clogging can be caused by air, dust, or dirt getting into the fluid. In consequence of the first variant, the jack stop can be not lifted, strongly spring or even lowered under load. The accumulated clumps of dirt, can limit the movement of valves that will no longer tightly close the channels, allowing the fluid to pass in both directions. In this case, the stop will not stay in one position, gradually lowering to the zero point. When figuring out why the hydraulic jack does not hold, the first thing to look at is the cleanliness of the system.

Valve failure, in addition to mud clogging, can be caused by mechanical damage. The ball at the end of the spring resting in the cone shaped groove may become detached or catch on other elements of the structure. In this case, the stem will not rise at all because fluid circulation in the system is impaired and pumping is not performed. This failure is more complex and requires disassembly of the device. It is not advisable to consider it before checking the system for clogs.

Stem damage can be caused by improper maintenance or storage, by handling heavy loads or by poor operation practices. In the first case, the piston can be covered by corrosion, which will reduce the tightness of its adherence to the cylinder, as a result of which the fluid will leak. If you lift weights, heavier than the allowable norm, the stop can bend. Chances of such breakage increase with maximum extension of screw and uneven installation of jack on the ground. Deformation of the stem is considered to be the most serious failure, which is not always repairable even in special centers.

Having highlighted the main causes of failure, let’s move on to specifics. Let’s look at the main problems and suggest solutions.

Not holding under load

Piston rod failure when resting on the load, even without a lot of pressure, can have two causes: insufficient oil or faulty valves. It is better to find out for sure, why the hydraulic jack is going down, from the simple to the complex. Let’s look at each option individually, in terms of complicating the repair procedure.

  • Lack of oil is connected with trivial leakage in the absence of sealing. This can be caused by storing the tool for a long time with the stop valve unscrewed or by worn gaskets. The problem is solved by refilling the liquid and pumping jack. It is better to use special hydraulic oil, but a simple industrial oil will do. If after filling the fluid leaks, even when the valve is closed tightly, it is worth buying a repair kit and replace all gaskets.
  • Failure of valves may be caused by clogged system or mechanical damage. If it does not hold the hydraulic jack, do not disassemble it at once. It would be more rational to first flush the internal passages, which may be clogged with dirt. To do this we drain all oil from the system and fill with flushing fluid (kerosene or gasoline can be used). Pump and drain a few times and repeat the procedure a couple more times with clean fluid.
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If flushing did not work, you will have to disassemble the body and inspect the valves. They may be loose due to loose springs or worn balls. The first option is more likely and can be repaired by replacing the spring or placing a small washer under it to increase the pressure force by reducing the distance to the bolt. A worn or chipped ball needs to be replaced. These can be found in the repair. kits available at auto dealers or from a suitable bearing.

Does not lift firmly

One of the most common problems with hydraulic jacks is that the rate of advancement of the hydraulic ram is reduced to a minimum or to no advancement at all. This failure is often caused by a decrease in lift height and a decrease in maximum load. The main reason for this malfunction is due to air entrapment in the system resulting from a drop in the oil level. To restore the effectiveness of the device, in this case, is not very difficult. You will need some oil (150-300 ml) and flushing fluid (if the tool is more than 2 years old).

  • First unscrew the stop valve one turn from the tightened position. Then lower the pump piston and the stopper to zero point.
  • Unscrew or remove (if rubber) the plug on the fill hole and drain the old oil into any container.
  • If the device is several years old, it is likely that its internal channels could be clogged with dirt, which can be just as good a reason why the hydraulic jack won’t lift properly. It is recommended to flush the device, preferably several times. For this, kerosene or gasoline can be used. Simply pour the fluid through the hole where you drained the oil, close the valve, raise the stop by pumping, open the valve, lower the stop and repeat the process two times. Then drain off the rough liquid, pour in a new clean portion and proceed as described above at least 1 time (look at the cleanliness of the drained mixture).
  • When you are sure the system is clean, you can fill it with oil. Almost all varieties can be used here, except for brake fluid. The main thing is that the consistency should not be too thick. It is desirable to use a special hydraulic or synthetic industrial.
  • Before pouring in the oil, lower the pump piston and stop to the zero position and screw in the valve. If the jack is a bottle-type jack, set it in vertical, working position while filling (a rolling jack is filled horizontally).
  • It is best to fill the jack with a syringe, smoothly pouring the liquid consistency until it fills the whole volume of the reservoir and starts to flow out of the hole.
  • After filling is completed, it is necessary to pump the system, to expel excess air from it. To do this, with the filler opening open, pump oil from the reservoir into the cylinder. When the stopper reaches maximum height unscrew stop valve and lower it. Repeat this procedure 2 or 3 times.
  • There is another way to pump without using a pump if the previous one did not work. You should unscrew the shutoff valve for 1-2 turns, then pull out with your hand and dip the rod into the cylinder, each time reducing the height of elevation by 1 cm until you reach the zero mark.

Briefly about the main faults

Most often on forums you can meet complaints that the hydraulic jack does not lift.

Why the bottle jack does not work?

Little oil in the tank, the rod does not rise to the height specified in the technical documentation. To repair with our own hands, we just need to add oil. Open oil fill cap, pour, then pump the jack, how to do it is described at the end of the article.

Oil is leaking. It happens so that oil leaks in the places, rubbers and seals, it is the first sign of that it is necessary to make overhaul, replace all gaskets and seals, to flush. To make a repair of the hydraulic bottle jack by yourself you will need a repair kit.

Under load, it sags. It occurs because of the air inside, one of the rubbers or gaskets passes the oil and instead of it gets into the working chamber air, which has the property to be strongly compressed under load. To correct the fault it is recommended, to repair the jack, change all gaskets and refill with new oil.

Ways of troubleshooting

Oil leakage is the main problem that causes the jack to not lift up to the end (with a small leakage) or at all (with a significant). Because of this air gets into the cavity, then the hydraulic jack works at a low force or refuses to work at all. Leakage in the hydraulic system can be prevented by routine maintenance, checking the oil level. In the case of a low level, simply fill up the fluid to the normal level.

Oil level drop can occur naturally or as a result of wear and tear or damage of oil seals and oil seals. In this case you won’t get away with just adding oil, you will need to change the o-rings.

Air is leaking into the hydraulic system because of the lack of fluid. This problem is solved by pumping: you need to unscrew the plug of the oil tank and overflow valve, and then just pump the system, that is move the lever up and down until the fluid flows into the main cylinder.

Corrosion on the pistons, rods and cavity of the hydraulic jack is often the cause of malfunction. To find out the cause and repair in detail, you will have to disassemble the device.

The bent rod is also a frequent reason why the jack does not lift or works with jerks. In this case, you can change the element by taking an analogue from an older model, or buy a new part. In most cases such faults can’t be repaired at all, even in a workshop or service center. This is because the stem usually bends under impact loading and there is damage to the main body components. In this case, it is cheaper to buy a new unit, not involved in the restoration or replacement of individual parts.

Better to remove dirt with kerosene.

When the diverter valve becomes deformed or just has a build up of dirt in it, the valve ball sits tightly in the seat and hydraulic fluid leaks through it. In that case, you will simply have to replace it and change the old (contaminated) oil with new.

Oil change

Bottle products

Bottle jacks have the ability to lift loads, ranging from 3 to 200 tons. This is ensured by a large support plane.

Single rod. Because they’re easy to use, they’re used in mechanical engineering and construction. The jack is adopted by car enthusiasts. for lifting cars. Used as an assembly in a pipe bender or press.Bipods. Works both vertically and horizontally. The device includes 2 stems. They are raised by the cylinder.

How to Repair a Bottle Equipment?

The repair of the bottle mechanism consists of steps:

The cause of the problem is determined. If the product is not holding the load. the seals are worn out. Difficult movement of the rod indicates that it is deformed and jammed.2. The assembly is disassembled. Particular attention is given to the fasteners. It is carefully removed. Any damage can lead to oil leakage.3. Each part is inspected. Often at this stage, the reason lies on the surface. Wear on the seals is clearly visible. Deformation of some parts can be easily identified.4. Worn out parts that cannot be repaired must be replaced. Repair those that can be repaired. After that, the jack is assembled.

After determining the cause of the failure, the repair process begins. It can be carried out with your own hands:

Worn seals are removed and new ones are installed in their place.2. A bent rod must be replaced.3. If there is corrosion on the mirror surface of the cylinders, they must be replaced. It is not economical to send it for sanding.

The assembled device is checked for proper operation: it is important to properly install the rubber rings, otherwise the unit will not hold pressure.

Sometimes you just need to add oil to the jack, which has dropped below the level. The work consists of the following steps:

3 The jack is lowered by turning the screw.2. The plug is unscrewed.3. Pour oil into the hole up to a fixed mark.4. The plug is screwed in and the unit is pumped several times.5. The oil level will then drop.6. The next priming follows and pumping is done again.7. The process is repeated several times.

After longer periods of use the machine needs to be flushed. It is carried out in the following sequence:

The first step is to drain out the old fluid.2. A flushing solution is poured in.3. After it has been drained off, the oil filling procedure is proceeded as usual.

The following tips should be observed during work:

The oil change procedure is conducted on the equipment that is standing unloaded.2. Any brand of filler material is used. In winter time more synthetic additives are added.3. It is not advised to use the machine for a long time in winter.4. The oil change interval is half a year. In the case of frequent use, this period is reduced to 1 month.

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Do not store the tool in sub-zero temperatures because the oil can freeze.

Repair and maintenance.

In order to service the bottle jack it must be disassembled. No need to worry about splashing yourself with oil from the high pressure. It is quite possible to do this operation by yourself. The first thing to do is to drain the oil. Drain through the filler hole, and if it is absent through the bypass valve, to do this unscrew the upper hex nut and completely unscrew the lower cock. We remove the body, check its tightness and evaluate the condition of the bottom rubber ring. These parts do not bear any load, this is just a reservoir for liquid. Then we unscrew the operating cylinder and remove the piston. All carefully inspected for rust. If it is found, get rid of it as carefully as possible. Unscrew the plug, check its working condition, examine the o-rings. There must not be any iron chips inside, nor any dents. Replace worn seals with new ones. Don’t forget to thoroughly wash all valves from dirt and various deposits. We reassemble it, and that’s it, the repair is done.

The first mentioned, the most widespread and well known are bottle jacks, they are often (by the most classical use) called car hydraulic jacks.

Most manufacturers start with one and a half ton jacks and reach 15 to 20 ton modifications. They are simple in design, compact in packing and unpretentious in service, they are capable to serve a diligent car owner faithfully for many years.

Actually, maintenance in most cases is reduced to checking of oil level, its refilling if necessary and periodical idle running of the jack so that during the operation all its parts could be lubricated, springs could work and balls of bypass valve could turn, which would prevent them from sticking due to rare operation and would not lead to inoperability of the device in emergency situation.

Just because of possibility of oil leakage bottle jacks are better to store in vertical position.

Repair of such jacks is very seldom, but if the jack is working hard, e.g. at a service station or in other industry, it usually comes to replacement of the piston and plunger seals, rubber seals, more seldom. springs and balls of the overflow valve.

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Advantages of the hydraulic bottle jack:

compactness; stability; durability; low applied force; universality of use. except for transport vehicles such jacks are used in construction, railway transport, as a strength unit for pipe benders and pipe cutters; easy to repair.

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These jacks are the main and practically non-alternative jacks on trucks.

high initial height; low lifting height; work in a non-vertical position is impossible.

Nowadays car hydraulic jacks are made in convenient compact package which makes their stowage and storage in the car, especially on long journeys very convenient and tidy and prevents from spoiling the things transported in the luggage compartment by possible oil leakage.

By the way, the shape of the drawers and the location of the handles hints transparently at the vertical storage of bottle-type jacks. A hydraulic jack has neither these disadvantages, but it is more expensive and less compact, but it is not inferior to the bottle-type jack and in some cases excels it:

when working on sites with a slope; has a much lower lifting height, it is easier to move and is installed under the car thanks to the wheels, has a higher lifting height (from 300 to 400 mm).

We would recommend to equip cars driven by women with bottle jacks.

Another, in our opinion, interesting model of car jack is created on connection of two types of this device: rhombic screw jack and hydraulic jack. It is certainly a hydraulic jack, but its force is transmitted by levers to the rhombic lifting device, which has undeniable advantages:

Low lifting height; absence of deviation in the vertical plane when lifting; high lifting height.

We would be wrong if we did not mention some of the lesser known, but no less useful hydraulic jacks.

Ways to eliminate faults

Oil leakage is the main reason the jack does not lift all the way (with a small leakage) or at all (with a significant leakage). Because of this air gets into the cavity, then the jack works at a low force or refuses to work at all. Leakage in the hydraulic system can be prevented by routine maintenance, checking the oil level. In case of low level you just need to add liquid to the norm.

Air leaking into the hydraulics due to lack of fluid. This problem is solved by pumping: you need to unscrew the plug of the oil tank and bypass valve, and then simply pump the system, that is, move the lever up and down until the liquid flows into the main cylinder.

Corrosion on the pistons, rods, and cavity of the jack is often the cause of malfunctioning. To determine the cause and repair in detail, the unit will have to be disassembled.

A bent piston rod is also a common cause of why a jack does not lift or jerks. In this case it is possible to change the element by taking an analog from an old model or buy a new one. In most cases such malfunctions cannot be repaired at all, even in a workshop or service center. This is because the rod usually bends under shock loads, and in this case the main body elements are damaged. In this case, it is cheaper to buy a new unit and not have to rebuild or replace individual parts.

When the bypass valve becomes deformed or simply has dirt accumulated in it, the ball of the valve sits tightly in its seat and hydraulic fluid leaks through it. In this case, it is necessary to simply replace it and change old (contaminated) oil with new one.

How to fill up the oil?

The hydraulic oil is poured through the neck on the side of the housing. It is also a level. There is no load on the plug and no pressure inside the body. Then the hydraulic jack must be pumped. This is a simple but responsible procedure.

After filling it is necessary to raise the rod to the maximum height (without load). Then the jack is placed horizontally, with the priming plug up. The plug is loosened and the piston rod is forcefully pressed into the cylinder. Most of the air is forced out into the reservoir of liquid.

Then the plug tightly closed, and make a few (up to 20) full cycles of raising to a maximum height with a load of 30-50 kg and the lowering of the rod. After that the test lift under increased load (100-500 kg) should be performed. If the jack “does not hold” the load. repeat pumping.

What kind of oil to use?? As specified in the data sheet or manual. If you have lost the paperwork, check the manufacturer’s website for information. Masters with experience advise to use t.н. the spindle. This is only true for older models.

There are still questions? Watch a video about repairing a 12-ton hydraulic bottle jack.

Without a jack, the motorist is literally left “without hands”. And you need it not only to change the wheel on the road. A good jack is indispensable for some repairs. especially in a regular garage, not equipped with an elevator. For example, when assembling a suspension after a repair, when it is necessary to do a final tightening of arms. There is no need to lower the car on the wheels for the silentblocks to take the “working” position. it is enough to jack up the arm to give it the right position. The hydraulic jack is especially handy. thanks to its design it can be placed under the part that is located low. so that no other jack will be able to get under it. But, like any other mechanism, the jack can fail. Repair of the jack is available to anyone who independently repairs a car. Let’s tell only about what in the first place you should pay attention to when repairing a jack with your own hands. First of all, let’s take a look at its structure.

How to troubleshoot and pump the jack with your own hands

Using a jack is effective, if you know how to pump the jack. Today it is impossible to repair a car without a jack. This is a special device, with the help of which you can lift loads of great weight. In providing the working force of such a mechanism involves a piston that has a hydraulic fluid.

Design and operating principle of a hydraulic jack.

hydraulic, jack, doesn, lift

Using the jack, wheel replacement is done, it allows you to repair the suspension of the car. There are the following types of jacks: retractable (rack) or jacking. The column jacks are pulled out vertically with one or more cylinders. Height of extension of the rack jack may be different.

The hydraulic car jack has a different design. The metal body of the device is mounted on four wheels, which are necessary for movement of the mechanism. A hydraulic cylinder, which has a lifting mechanism, is fixed in its holes. The platform is raised by having a special cylinder that extends horizontally.

What features are included in the hydraulic jacks?

The lever of the device provides actuation of the pump pumping hydraulic fluid into the cylinder through a special valve. The hydraulic or working fluid is the oil pressed into the cylinder. The jack is lowered back down with the valve located on the pump open so that the hydraulic fluid flows into the.

Hydraulic jacks are easy to use. They must be located on a level surface on the ground beneath the vehicle. After closing the valve of the device, its lever is pressed until the vehicle is raised to the required height from the surface.

To lower the car back to the ground when the wheel is already replaced, the valve opens smoothly counterclockwise. When the device is in its original position, close the valve back by turning it in the opposite direction.

How to Properly Pump a Jack

The jack, like any mechanism, requires periodic inspection and maintenance. Liquid can be refilled in the cylinder, as the use of the device is associated with oil leakage through the seals as well as the oil seals. When using the jack to repair the vehicle, use the safety jack stand. Adjusting the device with its help, you may not let the car fall to the ground in case the jack is defective.

Storage of the device in places where there is high humidity, leads to the appearance of rust on the cylinder. For the same reason, the working cylinder is capable of failing. However, the drawback of the hydraulic jack is the slow speed and low lifting height. Some models have sufficiently high own weight, so it is not too convenient to transport it in the trunk.

Instructions for properly pumping the jack device

Filling scheme of the hydraulic jack with oil.

Among the advantages of the jack are the rigid design, as well as the height of the lifting load from the ground, the greatest lifting capacity with smooth running, the minimum pick-up height. All these advantages give high efficiency.

Varieties and causes of breakdowns

Repair of the hydraulic jack is carried out with their own hands. For this purpose, all possible malfunctions and rules of their elimination are studied. Parts are prepared in advance. to replace the defective ones. The main causes of failure and the rules for their removal are known. To do this, please have a suitable tool at hand.

Hydraulic cylinder failure

If the hydraulic cylinder is defective, the oil reservoir must be removed. The piston must be unscrewed first. To do this, use wrenches to unscrew the screws located in the upper part. Protective rings are removed, the reservoir is pulled out. If the cylinder is damaged, it must be replaced. In the process of installation it is required to have a clamp. The screws unscrewed from the jack are replaced with new ones. They are of the same size. If sleeves are worn out, replace with new sleeves. Some models may be of the round type.

Upper and lower ring protrusion

If top ring is worn out, top plate must be unplugged. It must first be inspected for faults. The screws are unscrewed with wrenches. It is important to inspect the piston to make sure that a broken ring has not damaged it. After that, fit a new one to the piston rod. In order to improve the fixation, you should use a sealant.

If the lower ring is knocked out, the lower frame is removed. The hydraulic cylinder is inspected. Its integrity is checked. It is important that the piston moves smoothly, without jamming.

To remove the frame, the jack is turned over and fastened securely. The cover is removed only after the O-ring is inspected. Using a screwdriver, dismantle the retractable extension cord. It also needs to be inspected, as there is a risk of damage by the ring.

In the case of its replacement, specify the markings that are stamped on the body or written in the documentation.

Lubricate the rod with machine oil during installation. A new ring is also mounted.

Breakage of the pulling lever

The complexity of such repair is that it will require removal of both the traction device and the cylinder. First remove the top cover and inspect the cylinder. There may be scratches on it. Sometimes the movable plate also needs to be replaced.

The cylinder is removed using a clamp and the top plate is held by the rods. If there are several pistons in the construction, the coil must also be removed.

The traction device with the connected lever is on the bottom plate. To remove the lever, use a hammer to loosen the rod. As the last step, the lever is fixed to the pulling mechanism.

Wedge clamp breakage

If this fails, the top plate is removed. There are 4 screws that can be unscrewed. Use a screwdriver to pry open and remove the shackle. It is located near the oil system.

Locate the malfunctions

The rod extends to the desired height, but then slowly (without load) descends. in this case, the cause is most likely the bypass valve and damaged o-rings, so the correct pressure is not maintained.

If the jack does not lift up to the end, it means that working stroke decreased. In this moment corrosion on the rod and the mirror of the cylinder surface is the reason If the load to be lifted is greater than the jack’s lifting capacity (given in tonnes on the jack), the piston rod may be damaged or bent.

To keep the jack for a long time and not to break, you need to remember the following rules:

  • The hydraulic fluid needs to be changed twice a year.
  • If you use the jack every day, change the hydraulic fluid every month.
  • In extreme cases any hydraulic fluid can be used, but in winter time it is recommended to use synthetic oils specified by the manufacturer of the device.
  • To keep the oil from thickening in winter, keep the jack in a warm, dry place.
  • It is not recommended to operate the jack in winter in the cold, because it can simply stop working.
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To fix the failure you can lose a lot of time and money, so it is easier to follow the instructions for use of the hydraulic jack, and then it will last a long time and more than once will help to lift the load.

How the hydraulic jack works

To accurately determine the cause of the failure and its subsequent elimination, you should have a clear understanding of the principle of operation of the device. Fortunately, hydraulic jacks are arranged quite simply, and most of their faults can be eliminated by your own efforts. Contact the service may be necessary in cases of serious defects or complete lack of desire to familiarize with the repair manual. The basics of understanding the operation of the device, should be laid with the analysis of the main components of its mechanism.

Before describing the functional elements, it is worth noting that hydraulic jacks have several subtypes and are divided into jacks, bottle jacks and diamond jacks. To the classic type of liquid lifting mechanism, the bottle type is the closest, which includes devices with telescopic, hollow, hitch and standard rod. To form a proper basic idea, let’s take apart the original model without additional modifications. So, the hydraulic bottle jack, consists of the following components:

  • housing base. Supporting pad for placing the unit on a flat surface.
  • Housing. External part of the hydraulic jack and also the oil reservoir.
  • Plunger cylinder. Sealed chamber where fluid pressure is created, pushing out the rod.
  • Working plunger. Extendable element with a stop at the end.
  • Oil filling hole. Located in the upper, lateral part of the housing.
  • Screw. Extendable element for increasing the jack lift height. Screwed into plunger.
  • Body head. The threaded joint that locks the position of the body in relation to the cylinder.
  • O-ring. Seals oil reservoir, preventing fluid leakage.
  • Screw nut. Top of body head with six faces for easy unscrewing.
  • String. Handy element for manual jack transportation. Not available on all models.
  • Screw head. End of piston rod resting against load.
  • Lever. Removable hand pump element that increases impact force several times over. In most cases, includes a special slot for unscrewing the shutoff valve (more about it below).
  • Displacement plunger. The main element of the pump, driven by the lever. Pumps fluid from one reservoir to another.
  • Pump cylinder. Sealed chamber and intermediate element in the transfer of oil between the tanks.
  • Shutoff valve. Serves to connect / isolate oil reservoir with ram cylinder.
  • Suction valve. Controls fluid movement inside the unit, allowing fluid to flow only in one direction (only suction to pump cylinder).
  • Relief valve. Opposite of suction. Allows the pump plunger to squeeze oil through itself, but does not let it back in.

The basic action of the device is based on pumping fluid from the oil reservoir to the plunger cylinder. When you lift the lever, a portion of the oil is sucked into the pump cylinder, and when you lower it, it is squeezed into the main cylinder of the jack. Due to this, pressure is generated in the main compartment, pushing out the piston.

The main thing is to keep the compartment free of air, which can reduce stability and overall efficiency. It is for this reason that the bottle hydraulic jack does not work horizontally. However, even in this type of device, there are models that allow lifting in different positions.

The main malfunctions and their causes

Among all the reasons why a hydraulic jack does not work, we can distinguish 3 main variants: clogging of the system, failure of the valves or damage of the rod. It is on these 3 pillars that the most common failures are based, associated with reduced efficiency or complete failure of the system. For more clarity, let’s look at each case in more detail.

hydraulic, jack, doesn, lift

may be caused by air, dust or dirt in the fluid. In the consequence of the first variant, the jack’s stop may not rise, strongly spring or drop at all under the load. Accumulated clumps of dirt, can restrict the movement of the valves, which will no longer tightly close the channels, allowing the fluid to pass in both directions. In this case, the stop will not be fixed in one position, gradually descending to the zero point. When determining why a hydraulic jack does not hold, the first thing to look for is the cleanliness of the system.

, In addition to the mud clogging, can be caused by mechanical damage. The ball at the end of the spring, which is supported in the cone-shaped groove, may become detached or catch on other structural elements. In this case, the piston rod will not rise at all, because the liquid circulation in the system is not good and pumping is not performed. This failure is more complicated, and requires disassembly of the device. It is not recommended to consider it before checking the system for blockages.

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Can occur due to improper maintenance or storage conditions, as well as from working with large loads and violations of operating rules. In the first case, the piston can become corroded, reducing the tightness of the piston to the cylinder and causing fluid leakage. If you lift weights heavier than allowed, the stop may bend. The chances of such a breakdown increase with maximum extension of the screw and uneven installation of the jack on the ground. Deformation of the rod is considered the most serious breakage, which can not always be repaired even in special centers.

Having highlighted the main causes of faults, let’s move on to specifics. Let’s discuss the main problems and propose possible solutions.

Does not hold under load

Piston rod deflation at the load and even without strong pressure can be caused by two reasons: insufficient oil or defective valves. It is better to find out for sure, why the hydraulic jack goes down, from the simple to the complex. Let’s consider each variant separately, according to complication of repair procedure.

  • The lack of oil is associated with the banal leakage in the absence of sealing. May be caused by long storage of the tool with unscrewed shutoff valve or wear of gaskets. The problem can be solved by adding fluid and pumping the jack. It is better to use a special hydraulic oil, but even a simple industrial oil will do. If after filling, fluid is leaking even when the valve is closed tightly, it is worth buying a repair kit and replacing all the gaskets.
  • Failure of valves can be caused by clogging of the system or mechanical damage. If the rolling hydraulic jack does not hold, it is not necessary to disassemble it immediately. It is best to first flush internal passages which may be clogged with dirt. To do this, drain all the oil from the system and fill with flushing fluid (you can use kerosene or gasoline). Flush and drain a few times and repeat procedure a few more times with clean fluid.

If flushing is unsuccessful, the body must be disassembled and the valves inspected. They may be loose due to loose springs or have worn balls. The first option is more likely and can be corrected by replacing the spring or putting a small washer under it to increase the pressure force by reducing the distance to the bolt. A worn or chipped ball must be replaced. These can be found in. kits available at auto dealers or get them from a suitable bearing.

Doesn‘t lift well

One of the common troubles with hydraulic jacks is that the rate of extension of the rod is reduced to a minimum or to nothing at all. This failure is often connected with a decrease in the lifting height and a decrease in the maximum load. The main reason for such malfunction is due to clogging of the system resulting from a drop in the oil level. To restore the efficiency of the device, in this case, is not very difficult. It requires a little oil (150-300 ml) and flushing fluid (if the tool is more than 2 years old).

  • First unscrew the stop valve by 1 turn from the tightened position. Then lower the pump piston and the plug to the zero point.
  • Unscrew or remove (if rubber) the plug on the filler opening and drain the old oil into any container.
  • If the tool is several years old, it is likely that its internal channels could be clogged with mud, which may be just as good a reason why the hydraulic jack does not lift well. It is advisable to flush the device, preferably several times. For this, kerosene or gasoline can be used. Simply pour the fluid through the hole where you poured out the oil, close the valve, lift the jack stand by pumping, open the valve, lower the jack stand and repeat the process two times. Then pour in new dirty fluid and proceed as described above at least 1 time (look at the cleanliness of the fluid being drained).
  • When you are sure the system is clean, you can fill it up with oil. You can use almost all varieties here except brake fluid. The main thing is that the consistency should not be too thick. It is advisable to use special hydraulic or synthetic industrial oil.
  • Before pouring in oil, lower the pump piston and stop to the zero position and screw in the valve. If the jack is a bottle-type jack it should be set in vertical, working position while filling (a rolling jack is filled horizontally).
  • It is more convenient to fill the jack through a syringe, smoothly pouring the liquid consistency until it fills the entire volume of the reservoir and begins to flow out of the hole.
  • After filling is complete, the system must be pumped to expel excess air from the system. To do this, with the open pouring hole, pump oil from the tank into the cylinder. When the stopper reaches the maximum height, unscrew the stop valve and lower it. Do this procedure 2 or 3 times.
  • There is another way of pumping, without using a pump, if the previous one did not give results. It is necessary to unscrew the stop valve for 1-2 turns, then hand pull out and immerse the rod in the cylinder, each time reducing the height of lift at 1 cm, until you reach the zero mark.

Why won’t the jack go down or up?

Reasons why the jack refuses to work:

  • Cylinder failure. The working plane does not hold the load, as a result the liquid flows from the cavity to the space above the piston.
  • Mirror damage. The hydraulic system loses efficiency or simply fails, this is caused by improper transportation, it can lead to the fact that there is an oil leak and air enters the chamber, in this case, corrosion will definitely begin over time.
  • Corrosion. Rapid wear of oil seals and packings, which can result in contamination of the fluid and clogging of ducts and valves.
  • Dropping the unit. The higher the height from which the jack falls, the more serious can be the deformation of parts, major components.
  • Excessive strain. Causes the bending of the stem. This leads to warping of major components and leaking oil.
  • Improper use of the device, as well as untimely oil changes.

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Twisting of the rod