Strong 3Ton Hydraulic Floor Jack – Model STG3T

Types of hydraulic jacks and how they work

Hydraulic oils are almost incompressible. This feature has led to the use of hydraulic oils as a suitable means of conversion and transfer of work. Therefore, they can be used to design machines that, while simple, with a very low driving force can move an extremely high resistance force.

What is a hydraulic jack?

A hydraulic jack is a device in which a force is applied to the oil contained in a small cylinder. This force causes the incompressible oil to be transferred to the large cylinder. The oil presses on the piston of the large cylinder, causing the load on the cylinder (for example, the machine) to lift. The working mechanism of crane machines, etc. is such that at the same time, it does a lot of useful work with high efficiency.
The construction of the hydraulic jack uses the fact that the oil is almost incompressible and transmits the applied force. The pressure on the small piston is transferred directly to the large piston and pushes it upwards.

Mechanical advantage of hydraulic jack

The pressures on the cylinders, which are the same force on the surface unit, P = F / A, are equal. Therefore:

Pe = Pl

In other words, you can write:

Fe / Ae = Fl / Al

Where F is the same as the resisting and driving forces, A is the cross section of the two pistons. In its simplest form, the mechanical advantage of the hydraulic part of the jack is as follows:

AA = Ml / Ae

The jack handle is also a second type lever and has its own mechanical advantage. The lever handle increases the driving force. A useful force is applied to the hydraulic jack and the jack increases this force. Therefore, the mechanical advantage of the whole device is equal to the mechanical advantage of these two parts.

Does the hydraulic jack increase the amount of work?

There is no device that can increase the amount of work. Each amount of oil that comes out of the small cylinder, the same amount enters the large cylinder. In both cylinders, this volume of oil is equal to the product of the cross section of the cylinder at the distance at which the piston moves. Because these volumes are equal, therefore:

AeΔSe = AlΔSl

If we consider the car without friction, we have:

MA = Al / Ae = ΔSe / ΔSl

And because MA = Fl / Fe so:

FlΔSl = FeΔSe

Which shows that ideally the output or useful work is equal to the input or given work.

In pulleys, levers and hydraulic jacks, when there is no friction, the output work is equal to the input work. The same is true of other cars. Under such conditions, the ideal mechanical advantage (ie, without friction) of any machine can be obtained by examining the geometry of the machine. By considering the equation MA = ΔSe / ΔSl, even in the most complex machine, the ideal mechanical advantage can be found only by knowing how much the resistive force is displaced when we move the driving force over a certain distance.

Applications of hydraulic jacks

In lifting heavy vehicles and machines, compressor machines, cranes, refineries, underground drilling, tower building and architecture, all vehicles, etc., this very simple and useful device or its working mechanism is used.

Types of hydraulic jacks:

There are many types of hydraulic jacks. Here are some examples

Garage or repair shop hydraulic jacks: This type of jack is one of the simplest types of jacks that are used in workshops and car repair shops, such as:

Hydraulic lizard jack – smoothing jack – oil jack or bolt jack – pallet jack – engine jack and …

Special industrial jacks: These types of jacks are designed in large and medium industries and often by special engineering design for that specific job and is produced.