The hydraulic jack is up and not down

Table of Contents:

The hydraulic jack stops lifting, does not hold under load

Without a jack, the car enthusiast is literally “without hands”. And it’s not just for changing a wheel on the road. A good jack is indispensable for some types of repair work. especially in a regular garage, not equipped with a jack. For example, to reassemble the suspension after repairs, when it is necessary to do the final tightening of the arms. There is no need to lower the car on the wheels for silentblocks to take “working” position. it is enough to jack up the arm to give it the desired position. The hydraulic jack is especially handy: thanks to its design it can be installed under a low-positioned component, so that no other jack will allow to get under it. But, like any other mechanism, the jack can fail. Repair of jack is available to everyone, who repairs cars by himself. Let’s tell only about what you should pay attention to when repairing the jack with your own hands. First of all we shall consider its construction.

  • Stoppage. Happens due to the lack of fluid in the chamber or the presence of dirt in the oil.
  • Insufficient lifting height. Appears due to a limited amount of working fluid.
  • Slow lifting, jerks. Explained by the presence of air, as well as possible leakage in the hydraulic system.
  • Reduced pressure. You need to diagnose the valve or replace it. In this case, the jack also ceases to hold, lift fully, spring, can lower the load on its own.

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

How to properly fill up the oil

It is obligatory that the repair of the jack ends with the renewal of the working fluid. Before pouring oil into the hydraulic jack, you need to check that the air is completely deflated. Otherwise after that the system will not work at its full capacity. How to pump a hydraulic jack?

To do this, turn the exhaust valve counterclockwise. The device should be completely lowered down. To pump the hydraulic jack jack you can independently without using additional tools.

Then find the hole designed for pouring oil. It is located on the tank in which the hydraulic fluid is stored. Remove the bolt from the filler neck, insert the nozzle and pour in the oil. When the fluid starts to flow, you need to stop pouring it out.

Design and repair of a bottle-type hydraulic jack

Devices that lift weights to a certain height have become indispensable these days. Hydraulic bottle jack is a useful tool in construction, but especially in car repair. Car owners can’t imagine car maintenance without this wonderful device. If the jack is out of order. you just need to know how to repair it with your hands.

The design of a bottle jack

As can be seen in the figure the hydraulic bottle jack consists of the following parts:

When you create force on the lever (2), the rod (3) creates pressure which opens the valve (5), and the liquid flows into the working chamber (7). When the lever is pulled up the stop valve (5) closes and the fluid is sucked into the pump cavity from the oil storage tank (6) by the pressure of the suction valve (4). By pumping the fluid from the storage tank (6) into the working chamber (7) the main piston (1) is lifted.

In the working device, the well-known Pascal’s law is used: the pressure exerted on a fluid or gas is transferred to any point without change in all directions.

The bottle jack design is simple enough, we pump liquid from one reservoir to another, and thereby build up pressure in the second, thus raising the working piston.

Types, properties and characteristics of the hydraulic bottle jack

Jacks are divided into several types, the first division goes by the number of rods (half rods):

Fig. 2. Single rod jackFigure 3. Double rod jack

There is also a division according to the operating principle of the pump pumping liquid:

  • Manual, driven by user pressure on the lever
  • Larger pumps, designed for lifting huge weights, are driven by a separate actuator, a hydraulic pump or a hydraulic station.

Carrying capacity, an important parameter that determines the maximum mass to be lifted. Parameter depends on the volume of the working chamber and strength characteristics. Bottle-type devices have a lifting capacity from 2 to 100 tons.

Minimum lifting height, otherwise known as the minimum lifting height. This is the height at which the load should already be located, to be able to set the jack under it. Pay attention to the minimum height if you choose the device for the car. In the event that you have a low clearance (ground clearance), then the device of bottle type, by virtue of the high design will not suit you.

Maximum lifting height. The height to which the load can be lifted. The bottle jacks have a feature on the support platform that has a sliding screw that increases the minimum and maximum lift height.

Why the bottle jack does not work?

Little oil in the reservoir, the stem does not rise to the height specified in the technical documentation. For repairs with our own hands, we just need to add oil. Open the oil fill cap, pour, then pump the jack, how to do this is laid out at the end of the article.

Oil leakage. It happens so that oil leaks in the places, rubbers and seals, it is the first sign that it is necessary to make an overhaul, to replace all gaskets and seals, to make washing. To make a repair of a hydraulic bottle jack on your own will need a repair kit.

Under load, it sags. It is caused by air inside the jack, one of the rubbers or gaskets is leaking oil and instead of it air is getting into the working chamber, which has the property to be highly compressed under load. To fix the problem, it is recommended, to repair the jack, change all gaskets and pour new oil.

Repair and Service

To service the bottle jack it must be disassembled. You need not worry about being splashed with oil from the high pressure. It is quite possible to do this operation yourself. The first thing to do is to drain the oil. Drain through the filler hole, or through the by-pass valve if there is none, by unscrewing the upper hex nut and fully unscrewing the lower cock. We remove the body, check its tightness, and assess the condition of the bottom rubber ring.

These parts do not carry any load, they are simply the reservoir for the fluid. Then unscrew working cylinder and take out piston. Inspect everything carefully for rust. If it is found we need to get rid of it as carefully as possible. Unscrew plunger, check its performance, examine o-rings. There must not be any iron chips inside, and the parts should not have any dents. Replace the worn seals with new ones. Don’t forget to flush thoroughly all valves from dirt and various deposits.

We reassemble it and that’s it, the repair is done.

How to fill up the oil and pump the jack?

Oil is poured through the neck on the side of the body. The neck is also the level. Pour in the oil, then you need to pump the jack.

  • Lift the rod to the highest position without load using the lever
  • Then it’s placed on its side with the oil filler plug on top
  • The plug is loosened and the piston rod is pressed vigorously into the cylinder. The air should be bled from the working chamber.
  • The plug is closed, and 10-15 full raises and lowers the rod with a load of 40. 45 kg.
  • On the last cycle you should give an increased load and if the jack does not hold repeat the procedure.

Design and repair of a hydraulic bottle jack Link to main publication

Hydraulic jack will not lift under load

Sometimes there are problems with hydraulic jacks. Most people throw them out at once. But don’t throw it away, maybe the problem isn’t that big.

But sometimes it happens so. the jack does not raise to the necessary height. It used to be enough, for example, the length of the rod to lift the car, but now it is not. Halfway up and that’s it. Here the oil is to blame. precisely, it is lacking.

If the jack is working properly, it still uses oil. It’s not much, but it does with every lift/lowering. If it’s a good idea to change it from time to time, about once a year. But who in our country is engaged in such nonsense?) Usually works, as long as it works)

Anyway, I had two jacks malfunctioning. One jack, one bottle jack, both hydraulic, of course. The jack is the same as a bottle jack, only installed in a special design. After I lifted the car. they took their time lowering it. I decided to fill it up.

It is generally recommended to fill such jacks with special hydraulic oil. You can go and buy, you can pour spindle oil, which is also hydraulic. It is possible, at your own risk, to refill usual engine oil. Which I did. It’s not recommended, of course, it’s not the right kind of oil, but whatever

First you need to lower the jack completely. We unscrew the nipple, lower the rod (or the elevating part of the car jack), screw the nipple back on. We find the hole through which oil is poured. It’s covered with a rubber plug.

There are many varieties of lifting mechanisms, the most common among car enthusiasts hydraulic type of jacks (bottle, rolling jack). Jacks can fail if not properly maintained, for example, they stop lifting a load. And immediately there will be a question of what to do if the hydraulic jack does not lift. Do not necessarily immediately buy a new one, there is always a way out, often you can fix it, making maintenance of the unit.

Use of hydraulic jacks

Lifting appliances are used for fixing, moving and lifting heavy loads: construction slabs, machines, cars, columns. Capacities in the hundreds of tons. Machine design and dimensions vary depending on the application.

High performance and ease of maintenance make jacks indispensable in production, vehicle repair stations, the processing industry, power plants, warehouses and other industrial applications. Auto enthusiasts cannot do without their own compact elevators either.

And the ability to move loads vertically and horizontally is universally used on construction sites.

The design and operating principle of the hydraulic jack

To better understand why a malfunction occurred and what caused it, you should know how a hydraulic jack is built and how it works.

The design of the jack is quite simple: a body of hardened metal, a rod (or piston rod) and the working fluid. oil. The housing not only serves its intended purpose, but is also a complete working part of the jack. it is a reservoir for the liquid and a guide cylinder for the rod. Depending on the model, operation is by hand, air or foot-operated pump.

The jack works on the principle of communicating vessels. Т.е. due to the fact that the pumped oil from the pump enters the cylinder is squeezed out of the retractable valve and, consequently, raises the weight to the height, and to return it to its original position and lower the load, the release valve opens and the liquid flows back. Some models of hydraulic jacks have built-in pressure gauges to monitor operating pressure.

Design of the hydraulic elevator

The main components of the system are the body, the moving piston and the fluid medium (machine oil). The body is made of durable metal in the form of a cylinder. It serves both as a guide for the piston rod and as a reservoir for the technical fluid. Additional elements that drive the device to work:

The use of valves increases the force exerted on the lever tenfold. The plunger is needed to move the piston by transporting the working fluid into the reservoir below it. A valve prevents fluid from leaking back into the common container. The plunger gradually pumps more and more fluid under the piston, raising it. And for the weight to go down, it is only necessary to let the oil flow back into the reservoir by opening the valve.

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Pluses and minuses of hydraulic jacks

  • high capacity;
  • easy to operate and maintain;
  • high level of efficiency. about 80%;
  • Ability to move loads weighing up to 200 tons.
  • not able to lift loads from low height;
  • it is impossible to set the load lowering level;
  • require constant supervision and service: adding oil, replacement of gaskets and seals;
  • They can only be transported and stored in an upright position, otherwise the working fluid will leak out;
  • operate slowly enough, cyclically, lifting loads to a small height each time;
  • quite expensive;
  • They break more often and repair is more expensive than their mechanical counterparts.

Types of hydraulic jacks

Several types of devices have been created that are convenient for use in different areas:

The bottle jack is the most common and simple design. It can lift from two to a hundred tons, has a large support area and a compact body. Therefore, these mechanisms are commonly used in the repair of various types of vehicles, especially trucks. Bottle jacks can be of double-rod or single-rod design. The single-rod, simpler design is used for servicing railroad cars, in construction, engineering, manufacturing of pipe cutters and pipe benders. Double-rod models operate vertically and horizontally.

The car jack resembles a cart that moves under the load being lifted during operation. Operated by a hand lever and controlled by an oil valve. To open the valve, you twist the valve screw handle. Very good for one-way lifting of loads. So it’s good for changing wheels. But it works only on a rigid and level surface. There is a transmission variant that has a swivel frame in the design.

The hydraulic jack does not lift under load

Sometimes there are problems with hydraulic jacks. Most people throw them out right away. But don’t throw it away, maybe it’s not such a big problem.

Sometimes the jack doesn’t lift to the right height. Before, for example, there was enough rod length to lift the car, but now there isn’t. It goes halfway up and that’s it. It’s the oil. Or rather, the lack of it.

The oil is still used when the jack is in good working order. Not much, but it is consumed with every lift/lowering. It’s a good idea to replace it from time to time, about once a year. But who in our country does such nonsense?) Usually works as long as it works.)

hydraulic, jack, down

Anyway, my two jacks are malfunctioning. One jack and one bottle jack, both hydraulic, of course. A jack is the same as a bottle jack, only installed in a special structure. After I lifted the car, they took their time lowering it. I decided to refill the oil.

Generally it is recommended to fill such jacks with special hydraulic oil. You can go and buy it, or you can fill it with spindle oil, which is also hydraulic. Or, at your own risk, you can refill it with ordinary motor oil. Which I did. This is not recommended, of course, because the oil has different properties, but never mind

First of all, you have to lower the jack all the way down. We unscrew the jack, lower the jack tube (or the lifting part of the jack) and screw the tube back on. Find the hole through which the oil is poured. It’s covered with a rubber plug.

There are many varieties of lifting mechanisms, the most popular among car enthusiasts is the hydraulic type of jacks (bottle jack, jacking jack). With improper maintenance jacks can fail, for example, they stop lifting the load. And the question arises right away, what to do if the hydraulic jack won’t lift? Do not necessarily buy a new one, there is always a way out, you can often fix it by doing maintenance of the unit.

Hydraulic jack applications

Lifting devices are used for securing, moving and lifting heavy loads: construction slabs, machines, cars, columns. Capacities in hundreds of tons. The design and dimensions of the machine vary depending on the application.

High performance and ease of maintenance has made jacks indispensable in manufacturing, vehicle service stations, the processing industry, power plants, warehouses and other industrial applications. Car enthusiasts also do not do without their own compact elevators.

And the ability to move loads vertically and horizontally is universally used on construction sites.

Design and operating principle of the hydraulic jack

To get a better idea of why a malfunction has occurred and what the cause is, you need to know how a hydraulic jack is built and how it works.

The design of the jack is quite simple: a body of hardened metal, a piston rod (or retractable piston) and the working fluid is oil. The housing not only fulfills its direct purpose, but is also a full-fledged working part of the jack. it is a reservoir for the liquid and a guide cylinder for the rod. Depending on the model, operation is by hand, air or foot-powered pump.

The jack works on the communicating vessel principle. Т.е. the oil pumped from the pump enters the cylinder and squeezes the sliding valve and therefore lifts the weight to the required height and, in order to return it to its original position and lower the load, the releasing valve opens and the fluid flows back. Some hydraulic jack models have built-in pressure gauges to control operating pressure.

The design of a hydraulic jack

The main components of the system are the housing, the mobile piston, and the fluid medium (machine oil). Body is made of durable metal in the shape of a cylinder. It serves both as a guide for the piston rod and as a reservoir for the technical fluid. Additional elements that drive the device:

The use of valves allows the force exerted on the lever to be increased tenfold. Plunger is needed to move the piston by transporting the working fluid into the vessel below it. Valve prevents fluid from flowing back into the main tank. The plunger gradually pumps more and more fluid under the piston, raising it. And for the load to be lowered, it only needs to allow the oil to return to the common container by opening a valve.

Pros and cons of hydraulic jacks

  • high power;
  • easy operation and maintenance;
  • high level of efficiency. about 80%;
  • Can move loads weighing up to 200 t.
  • unable to lift loads from low heights;
  • The load lowering level cannot be set;
  • Requires constant monitoring and service: adding oil, replacing gaskets and seals;
  • they can be transported and stored only in an upright position, otherwise the working fluid will leak out;
  • They work quite slowly, cyclically, lifting the load to a small height each time;
  • are quite expensive;
  • They break more often and are more expensive to repair than their mechanical counterparts.

Types of hydraulic jacks

Several types of devices have been created that are convenient for use in different areas:

The bottle jack is the most common and simple design. It can lift from two to a hundred tons, has a large support area and a compact body. Therefore, such mechanisms are usually used in the repair of various types of vehicles, especially trucks. Bottle jacks can have a double rod or single rod design. Single-rod pump units of a simpler design are used for maintenance of railroad cars, in construction, mechanical engineering, in the manufacture of pipe cutters and pipe benders. Dual rod models work vertically and horizontally.

The car jack reminds a design of a cart, which during operation moves under the load to be lifted. Operated by a hand lever and controlled by an oil valve. To open the valve, you need to twist the handle of the valve screw. Very convenient for one-way cargo lifting. So it’s good for changing a wheel. But it only works on a firm and level surface. There is a transmissive variety that has a swivel frame in its design.

Hydraulic bottle jack does not lift all the way, what do I do if it does not lower?

There are many varieties of lifting mechanisms, the most popular among car enthusiasts is the hydraulic type of jack (bottle jack, rolling jack). Jacks may malfunction if not properly maintained, e.g., they stop lifting. And the question immediately arises, what to do if the hydraulic jack does not lift. It is not necessary to buy a new one at once, there is always a way out, often you can fix everything by doing maintenance of the unit.

Briefly about the main faults

The hydraulic jackFailures can be different, but have one common cause.

  • Stopping. Occurs due to lack of fluid in the chamber or contamination in the oil.
  • Insufficient lifting height. Occurs due to insufficient working fluid.
  • Slow, jerky lift. Explained by the presence of air as well as possible leaks in the hydraulic system.
  • Reduced pressure. Requires diagnosis or valve replacement. In this case, the jack also stops holding, lifts fully, springs, can lower the load on its own.

The most common complaint on the forums is that the hydraulic jack does not lift.

Specialists recommend to study well the lifting device, the scheme of its work, because the presence of faults or improper operation of the unit can cause serious injury to man or damage to the lifted load.

Design and principle of operation

The design of the hydraulic jacks is more or less the same for both car jacks and bottle jacks. The main parts of the roll-up devices:

Lifting the load should be done with the unit on a level surface. When a person squeezes the handle, the rod builds pressure, which causes the valve to actuate and the oil flows into the working cavity (chamber).Dirt on the valve

When the handle is pulled up, the shutoff valve is actuated and oil flows into the chamber through the suction valve. The piston is raised by pumping oil from the reservoir into the working chamber. Then, to lower the piston with the rod, the by-pass valve is opened, then the piston is lowered by the pressure of the load.

The jack is designed so that the jack will lower the piston rod with the load by slowly unscrewing the bleeder valve located on the jack body.

Why the jack will not lower or raise

Reasons why the jack refuses to work:

  • Cylinder failure. The working plane does not hold the load and causes the fluid to leak from the cavity into the supra-piston space.
  • Mirror damage. Hydraulics lose efficiency or simply fail, it is caused by incorrect transport, it may cause oil leakage and air penetration into the chamber and in this case corrosion will eventually occur.
  • Corrosion. Leads to rapid wear of sleeves and seals, as a result dirt may get into the liquid and clog channels and valves.
  • Dropping of the machine. The higher the height from which the jack falls, the more serious may be the deformation of parts, major components.
  • Too much load. Can lead to distortion of the spindle. This leads to misalignment of major components and oil leakage.
  • Improper use of the unit and untimely oil changes.

You might also be interested in Selecting and describing car jacksPiston rod warping

Troubleshooting

Oil leakage is the main problem that causes the jack to not lift all the way (with a small leakage) or at all (with a significant leakage). Because of this air enters the cavity, 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 the case of a low level, simply fill up the fluid to the normal level.

Decrease of oil level can occur naturally, and also as a result of wear or damage of seals and sleeves. You won’t get away with simply adding oil, the o-rings must be replaced.

Air leaks 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 the bypass valve, and then just pump the system, that is, move the lever up and down, until the liquid passes into the main cylinder.

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

A bent rod is also a common reason why a jack does not lift or jerks. In this case, you can change the element, taking an analogue from the old model, or buy a new part. In most cases such malfunction cannot be repaired at all, even in a workshop or service center. This is because the piston rod usually bends under impact loading and in that case the main body components are damaged. In this case, it is cheaper to buy a new unit rather than repairing or replacing individual parts.

When the bypass valve becomes deformed or simply has dirt accumulated in it, the valve ball sits tightly in the seat and hydraulic fluid leaks through it. If this is the case, simply replace the by-pass valve and change the old (contaminated) oil for new.

Fault detection

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

If the jack does not lift till the end, it means that working stroke decreased. At this moment the blame is corrosion on the rod and the mirror of the cylinder surface. If the load to be lifted is greater than the jack capacity (indicated in the certificate and on the body in tons), there is a possibility of damage to the rod, its distortion.

The jack does not come up to the end in its initial position, if you open the drain valve. it testifies about stretched springs, or they lost their elasticity.

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A short summary of the main malfunctions

The most common complaint encountered on forums is that the hydraulic jack won’t lift.

Design and principle of operation

The design of hydraulic jacks is about the same for both jacks and bottle jacks. The main parts of the jacking devices:

When the handle is lifted up, the shutoff valve is actuated, and oil flows into the chamber through the operation of the suction valve. Pumping oil from the tank into the cylinder cavity lifts the piston. Then, to lower the piston with the piston rod, the by-pass valve is opened, then the piston is lowered under load pressure.

hydraulic, jack, down

Why won’t the jack go down or up?

Reasons why the jack fails to work:

hydraulic, jack, down
  • Cylinder failure. The working plane cannot hold the load, as a result the liquid flows from the cavity to the space above the piston.
  • Damage to the mirror. The hydraulics loses efficiency or simply fails, this is caused by improper transportation, it can lead to oil leaks and air enters the chamber, in this case corrosion will definitely begin over time.
  • Corrosion. Leads to rapid wear of seals and glands, as a result dirt can get into the liquid and clogging of channels and valves.
  • Dropping the machine. The greater the height from which the jack falls, the more serious may be the deformation of parts, major components.
  • Too much load. Causes distortion of the jack stem. It leads to distortion of main assemblies and skipping of oil.
  • Improper use, as well as untimely oil changes.

Varieties and causes of failure

The hydraulic jack is repaired with your own hands. All possible faults and the rules of their elimination are known. Parts are prepared in advance. for replacement of defective parts. The main causes of failure and troubleshooting are known. For this, it is necessary to have a suitable tool at hand.

Failure of the hydraulic cylinder

In the event of a hydraulic cylinder malfunction the oil reservoir must be removed. First disconnect the piston. Use wrenches to loosen the screws located in the upper part of the jack. Protective rings are removed, the reservoir is pulled out. If the cylinder is damaged, it must be replaced. A clamp is required for installation. Bolts unscrewed from the jack are replaced with new ones. They are of the same size. If the piston sleeves are worn, replace them with new sleeves. Some models allow the use of a round type.

Upper and lower ring protrusion

If the top ring is out, the top plate is disconnected. It is inspected beforehand for any defects. The screws should be unscrewed using wrenches

It is important to inspect the piston and make sure that the broken ring has not damaged it. After that, a new one is installed on the rod

A sealant should be used to improve retention.

If the lower ring comes out, the lower frame is removed. The hydraulic cylinder is inspected. Check its integrity

It is important that the piston moves smoothly, without jamming

To remove the frame, the jack is turned over and secured securely. The cover is removed only after the o-ring is inspected. Use a screwdriver to remove the extension arm. It, too, must be inspected because there is a risk that it will be damaged by the ring.

If it is replaced, the markings on the body or written in the documentation must be checked.

Lubricate the piston rod with machine oil during insertion. The new ring is also fitted.

Breakage of the traction lever

The complexity of this repair is that it is necessary to remove both the traction lever device and the cylinder. First remove the top cover and inspect the cylinder. Scratches may be present. Sometimes the slide plate also needs to be replaced.

The cylinder is removed using a clamp, and the top plate is held on the rods. If the design contains several pistons, removal of the coil is also required.

The pulling device with the connected lever is on the bottom plate. To remove the lever, the rod is released with a hammer. In the last stage, the lever is fixed to the pulling mechanism.

Breakage of the wedge gripper

In the case of such a failure, the top plate is disconnected. To do this, 4 screws must be unscrewed. Use a screwdriver to pry open and remove the cable tie. It is located near the oil system.

What to do if the hydraulic jack doesn’t lift??

Devices that lift loads up to certain heights are indispensable nowadays. The hydraulic bottle jack is a useful tool in construction and especially in car repair. Car drivers can’t imagine car maintenance without this wonderful device. If the jack is out of order you just need to know how to repair it with your own hands.

The design of a bottle jack

As you can see in the picture, the hydraulic bottle jack consists of the following parts:

When the lever (2) is actuated the rod (3) creates pressure which opens the valve (5) and the fluid flows into the working chamber (7). When the lever is moved upwards the stop valve (5) closes and the liquid is sucked into the pump cavity from the oil storage tank (6) by opening the suction valve (4) under pressure. By pumping fluid from the reservoir (6) into the working chamber (7), the main piston (1) is raised.

In operation, the well-known Pascal’s law is used: the pressure exerted on a liquid or a gas is transmitted to any point without change in all directions.

The bottle jack design is simple enough, we pump liquid from one reservoir to the other and thus build up pressure in the second, due to what we lift the working piston.

Hydraulic bottle jack types, features, and characteristics

Jacks are divided into several types, the first division being the number of rods (half rods):

Fig. 2. Single rod jackFigure 3. Double rod jack

There is also a division according to the operating principle of the liquid pump:

  • Manual, actuated by user pressure on a lever
  • Large pumps designed to lift a huge mass, driven by a separate drive, a hydraulic pump or a hydraulic station.

Carrying capacity, an important parameter that determines the maximum mass to be lifted. the size of the working chamber and the strength of the cylinder. Hydraulic bottle jacks have a lifting capacity of 2 to 100 tonnes.

Minimum lifting height, also called the minimum lifting height. This is the height at which the load should be at, to be able to set the jack under it. Note the minimum height if you are selecting a device for the car. If you have a low clearance (ground clearance), then the device of bottle type due to the high design will not suit you.

The maximum lifting height. The height to which the load can be lifted. The bottle ones have a peculiarity, on the support platform there is a sliding screw that increases the minimum and maximum lifting height.

Why is the bottle jack not working??

Little oil in the tank, Piston rod does not rise to the height specified in the technical documentation. To repair with your own hands, we just need to add oil. Open the cap filling the oil, pour, then pump the jack, how to do this is laid out at the end of the article.

Oil leakage. It happens so that oil leaks in places, rubbers and seals, it is the first sign that it is necessary to make overhaul, replace all gaskets and seals, to carry out washing. You will need a repair kit to perform the repair of the hydraulic bottle jack yourself.

Sags under load. It happens because of the air inside, one of the rubbers or gaskets leaks oil and instead it gets into the working chamber of the air, which has the property to be highly compressed under load. To correct the malfunction it is recommended, to repair the jack, change all the gaskets and pour in new oil.

Repair and Service

To service a bottle jack, it must be disassembled. There is 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, or if there is no filler hole, through the bypass valve by unscrewing the top hex nut and completely unscrewing the bottom cock. Remove the housing, check its tightness, assess the condition of the lower rubber ring.

These parts do not carry any load, they are just a reservoir for the fluid. Next we unscrew the operating cylinder and remove the piston. Check carefully for any rust. In case it is found, get rid of it as carefully as possible. Unscrew the plunger and check its performance, inspect the seals. There must be no iron shavings inside and no dents. If the sealings are worn out they should be replaced by new ones. Do not forget to flush thoroughly all valves from dirt and various deposits.

Let’s reassemble it and that’s all the repair is done.

How to pour oil and pump the jack?

the oil must be poured through the neck on the side of the body. The same neck is the level. fill up with oil, then pump the jack.

  • Lift the jack to the highest position without load by operating the lever
  • Then put it on its side, the filler plug should be on top
  • The plug is loosened and the piston rod is pressed vigorously into the cylinder. The operation is made to squeeze the air out of the working chamber.
  • The plug is closed, and made 10-15 full lifts and lowers the rod with a load of 40. 45 kg.
  • On the last cycle, an overload should be given and if the jack does not hold, the procedure must be repeated.

Design and repair of the hydraulic bottle jack Link to main publication

The hydraulic jack does not lift until the end, what to do if it does not descend

There are many varieties of lifting mechanisms. The most popular type of jacks among car enthusiasts is the hydraulic one (bottle jack, car jack). If not properly maintained, jacks can fail, such as they stop lifting the load. And immediately the question arises what to do if the hydraulic jack does not lift. It is not necessary to buy a new one at once, there is always a way out, often it can be corrected by doing maintenance of the unit.

Why the jack doesn’t lift up to the end?

There are many varieties of lifting mechanisms, the most common among car enthusiasts is the hydraulic type of jack (bottle, rolling jack). If not properly maintained, jacks can fail, such as they stop lifting a load. And the question immediately arises what to do if the hydraulic jack does not lift. It is not necessary to buy a new one at once, there is always a way out, often all can be corrected by doing maintenance of the unit.

About repairing 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 squeezed out in the cylinder. The jack lowers back down when the valve located on the pump is open so that the hydraulic fluid flows into it.

Hydraulic jacks are not difficult to use. They should be located on a level ground surface under the vehicle. After closing the flap of the device, the lever of the device is pressed until the car is raised to the necessary height from the ground.

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, the valve is closed back by turning it in the opposite direction.

How to properly pump the 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 a vehicle, use the safety jack stand. Use it to hold the jack in order to prevent the car from crashing to the ground in the event of a jack malfunction.

Storing the unit where there is excessive moisture will cause the cylinder to rust. For the same reason the working cylinder can fail. However, the disadvantage of the hydraulic jack is the slow speed and low lifting height. Some models have a sufficiently large empty weight, so it is not too convenient to carry in the trunk.

How to fill up the oil?

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

After priming, it is necessary to raise the rod to its maximum height (no load). Then the jack is placed horizontally, with the filling plug upwards. The plug is loosened and the piston rod is pressed vigorously into the cylinder. Most of the air is pushed out into the reservoir with the fluid.

Then the plug is tightly closed, and several (up to 20) full cycles of lifting to the maximum height with a load of 30-50 kg and the lowering of the rod. After that you should do a control lifting under increased (100-500 kg) load. If the jack “does not hold the load” repeat the pumping.

What oil to fill? The one that is specified in the product data sheet or in the manual. If you have lost documents. find information on the site of manufacturer. Masters with experience advise using a t.н. spindle oil. This is only true for older models.

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

It is no exaggeration to say that without a jack the motorist remains “without hands”. You need it not only for changing a wheel on the road. A good jack is indispensable for some types of repair work. especially in a regular garage, not equipped with a jack. For example, when assembling the suspension after repair, when it is necessary to make the final tightening of the levers.

There is no need to lower the car on the wheels for the silentblocks to take “working” position. it is enough to jack up the arm to give it the desired position. The hydraulic jack is especially handy. Thanks to its design, it may be installed under a low-positioned component, so that no other jack will allow to get under it. But like any other mechanism, the jack can fail.

Repair of hydraulic jack is available for everyone, who repairs cars by himself

Let’s tell only about what you should pay attention to when repairing the hydraulic jack with your own hands. Let’s consider its construction

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

Oil leakage can become one of the most widespread reasons of jack failure. As a result, the air enters the working chamber, as a consequence, the lifting mechanism does not work in full force or ceases to function.

To avoid this problem, periodic maintenance of the hydraulic jack is to check the amount of liquid and top up the working cylinder as needed. Reduction of oil in the system can be a consequence of natural operational losses, as well as due to damaged or faulty seals and packings. In this case, regular topping up the fluid will not solve the problem, you will need to replace worn seals and packings.

Due to the lack of working fluid in the system, its place is taken by air. this can be guessed from 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 this is the cause, the jack will be back in service if this work is done properly. But if that doesn’t help, either the cause of the malfunction is different, or a more serious repair is needed.

Sometimes you can solve this problem by unscrewing the locking needle for two turns, simultaneously raising the piston to the upper point, and then releasing it so that it reaches the lower. This should be repeated two to four times.

If corrosion is detected and parts are damaged, they must be replaced.

Often the reason of incorrect work of the hydraulic jack may be corrosion, affecting the retractable pistons (rods or plungers) and the inside of the housing. But to find out the cause, you will 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 jack is also often the reason of failure of the jack, in which case, if the design features of the model provide, it can be replaced for a new one, but often it means that the jack can not be repaired even in the service shop.

How the hydraulic jack works

To be able to pinpoint the cause of a malfunction and then fix it, it is important to have a clear understanding of how the tool works. Fortunately, hydraulic jacks are arranged quite simply, and most of their malfunctions can be repaired on their own. Appeal to the service may be necessary in cases of serious defects or complete lack of desire to familiarize with the instructions for repair. The basics of understanding the operation of the device should be laid by taking apart the basic components of its mechanism.

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

  • Body base. Supporting pad for placing the unit on a flat surface.
  • Body. External part of the hydraulic jack and also the oil reservoir.
  • Plunger cylinder. Sealed chamber where pressure is created by the fluid pushing the piston rod out.
  • Working plunger. Extendable element with a stop at the end.
  • Oil filling port. Located on top, side of unit housing.
  • Screw. Retractable element for increasing the jack lift height. Screws into plunger.
  • Body head. Screw joint securing the position of the housing to the cylinder.
  • Sealing ring. Seals oil reservoir, preventing fluid leakage.
  • Screw nut. Top part of the housing head with six faces for easy unscrewing.
  • Earring. Handy element for transporting the jack by hand. Not available on all models.
  • Screw head. The end part of the piston rod resting against the load.
  • Lever. Removable element in a hand pump that increases the force of the pump by several times. In most cases, includes a special slot for unscrewing the shutoff valve (more about it later).
  • Displacement plunger. Main pump element that is actuated by the lever. Pumps fluid from one reservoir to another.
  • Pump Cylinder. Sealed chamber and intermediate element in transferring oil between the tanks.
  • Shutoff valve. Used to combine/isolate the oil reservoir with the ram cylinder.
  • Suction valve. Regulates 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 out, but does not let it back in.

The action of the device is based on pumping fluid from the oil reservoir to the plunger cylinder. When raising the lever, the oil portion is sucked into the pump cylinder, and when lowered, it is squeezed into the main cylinder of the hoist. 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. This is the reason why the hydraulic bottle jack does not work horizontally. However, even in this type of devices there are models that allow you to lift in different positions.

The main malfunctions and their causes

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

A clogged system can be caused by air, dust, or dirt getting into the fluid. In consequence of the first variant, the jack stand may not rise, strongly spring or even sink under load. Accumulated clods 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 jack stand will not stay in one position, gradually lowering to the zero point. The first thing to look for when determining why a hydraulic jack won’t hold is the cleanliness of the system.

Valves failure, in addition to clogging by dirt, may be caused by mechanical damage. The ball at the end of the spring resting in the cone-shaped groove may disengage or get caught in other elements of the structure. In this case, the rod 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 unit. It is not recommended to consider it before checking the system for clogs.

piston rod damage can be caused by improper maintenance or storage, by handling heavy loads, or by improper use. In the first case, the piston can be covered with corrosion, which will reduce the tightness of its adherence to the cylinder, resulting in fluid leakage. If you lift heavier loads than are permitted, the stopper can bend. The chances of this failure increase when the screw is extended as far as possible and the jack is not level on the ground. Deformation of the piston rod is considered to be the most serious breakage, which cannot always be repaired even in specialized centers.

Having covered the main causes of faults, let’s move on to specifics. Let’s break down the main problems and suggest solutions.

Does not hold under load

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

  • Lack of oil is connected with trivial leakage if there is no sealing. May be a consequence of long storage of the tool with unscrewed shutoff valve or wear of gaskets. The problem is solved by refilling the liquid and pumping the jack. It is better to use a special hydraulic oil, but a simple industrial oil will do. If after filling the fluid leaks, even with a tightly closed valve, it is worth buying a repair kit and replace all the gaskets.
  • Valve failure can be caused by a clogged system or mechanical damage. If the hydraulic jack does not hold, it is not necessary to disassemble it right away. It’s better to flush internal passages first, as they might be clogged with mud. To do this, we drain all the 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 few more times with clean fluid.

If flushing does not work, you need to disassemble the body and inspect the valves. They can become loose due to loose springs or 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. Worn or chipped ball needs replacing. You can find them in the repair shop. For this reason, it is best to remove the spark plug from the housing in kits available in specialised dealers or from a suitable bearing.

Does not lift well

One of the most common problems with hydraulic jacks is that the extension speed of the piston rod is reduced to a minimum or to no extension 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 that the system is bled, due to a drop in the oil level. In this case it is not difficult to restore the efficiency of the unit. You will need some oil (150-300 ml) and flushing fluid (if the tool is more than 2 years old).

  • The first thing to do is to unscrew the shutoff valve one turn from the tightened position. Then lower the pump piston and the stop to zero point.
  • Unscrew or remove (if rubber) plug on the fill hole and pour out the old oil into any container.
  • If the device is several years old, it is likely that its internal channels may be clogged with dirt, which can be just as good a reason why the hydraulic jack does not lift well. It is recommended to wash the device, preferably several times. For this, you can use kerosene or gasoline. Simply pour the fluid through the hole where you poured the oil, close the valve, raise the stop pumping, open the valve, lower the stop and repeat the process two times. Then we drain the brake fluid, pour a new portion of clean fluid and proceed as described above at least 1 time (look at the purity of the drained mixture).
  • When you are sure the system is clean, you can fill it up with oil. Here you can use almost all varieties except brake fluid. The main thing is not to make it too thick. It is desirable to use special hydraulic or synthetic oil.
  • Before pouring in the oil, lower the pump piston and stopper 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 better to fill up the jack with syringe, smoothly pouring liquid substance until it fills all volume of the reservoir and begins to flow out of the hole.
  • After completing the refueling, it is necessary to pump the system, kicking out the excess air from it. To do this, with the filler opening open, pump oil from the reservoir to the cylinder. When the stopper reaches the maximum height, unscrew the stop valve and lower it. Do the procedure 2-3 times.
  • There is another way of pumping, without using a pump, if the previous one did not work. You should unscrew the lock valve for 1-2 turns, and then pull out a hand and immerse the rod into the cylinder, each time reducing the height of lift 1 cm until you reach zero.