Hydraulic cylinder working principle diagram, hydraulic cylinder structure diagram

What is a hydraulic cylinder

A hydraulic cylinder is a hydraulic actuator that converts hydraulic energy into mechanical energy and performs linear reciprocating motion (or swing motion). It has a simple structure and reliable operation. When using it to achieve reciprocating motion, the deceleration device can be eliminated, there is no transmission gap, and the movement is smooth, so it is widely used in the hydraulic systems of various machinery. The output force of the hydraulic cylinder is proportional to the effective area of ​​the piston and the pressure difference on both sides.





Hydraulic cylinder structure diagram


Hydraulic cylinders usually consist of rear end cover, cylinder barrel, piston rod, piston assembly, front end cover and other main parts;in order to prevent oil from leaking out of the hydraulic cylinder or from high-pressure chamber to low-pressure chamber, the cylinder barrel, end cover, piston There are sealing devices between the piston rod, the piston and the cylinder barrel, the piston rod and the front end cover. There is also a dustproof device on the outside of the front end cover;in order to prevent the piston from hitting the cylinder head when it quickly returns to the end of the stroke, the hydraulic cylinder end A buffer device is also provided at the bottom;sometimes an exhaust device is also required.





Classification of hydraulic cylinders
In order to meet the different purposes of various hosts, there are many types of hydraulic cylinders.
According to the oil supply direction, it can be divided into single-acting cylinder and double-acting cylinder. The single-acting cylinder only inputs high-pressure oil to one side of the cylinder, and relies on other external forces to make the piston return in the reverse direction. The double-acting cylinder inputs pressure oil to both sides of the cylinder respectively. The forward and reverse movements of the piston are accomplished by hydraulic pressure.
According to the structural form, it can be divided into piston cylinder, plunger cylinder, swing cylinder and telescopic sleeve cylinder. According to the form of piston rod, it can be divided into single piston rod cylinder and double piston rod cylinder.
According to the special purpose of the cylinder, it can be divided into series cylinder, booster cylinder, speed-increasing cylinder, stepping cylinder, etc. This type of cylinder is not a simple cylinder, but is combined with other cylinders and components. Therefore, from a structural point of view, this type of cylinder is also called a combination cylinder.





Hydraulic cylinder working principle diagram


Hydraulic transmission principle - oil is used as the working medium, motion is transmitted through changes in seal volume, and power is transmitted through the pressure inside the oil.
1. Power part - converts the mechanical energy of the prime mover into the pressure energy of the oil (hydraulic energy). For example: hydraulic pump.
2. Execution part - converts the oil pressure energy input by the hydraulic pump into mechanical energy that drives the working mechanism. For example: hydraulic cylinder, hydraulic motor.
3. Control part - used to control and adjust the pressure, flow and flow direction of the oil. For example: pressure control valve, flow control valve and directional control valve.
4. Auxiliary part - connect the first three parts together to form a system, which plays the roles of oil storage, filtration, measurement and sealing. For example: pipelines and joints, fuel tanks, filters, accumulators, seals and control instruments, etc.





The pressure exerted at any point on a certain volume of liquid can be transmitted equally in all directions. This means that when multiple hydraulic cylinders are used, each hydraulic cylinder will pull or push at its own speed, and these speeds are determined by the pressure required to move the load.
When hydraulic cylinders have the same load capacity range, the hydraulic cylinder carrying the smallest load will move first, and the hydraulic cylinder carrying the largest load will move last.
In order to make the hydraulic cylinders move synchronously so that the load is lifted at the same speed at any point, a control valve or a synchronous lifting system component must be used in the system.