Hydraulic cylinder design and working principle
A cylinder’s reliability depends on the quality of every part, accurate dimensions and correct assembly. Here are the main parts and what they do.
Cross-section of a double-acting cylinder
- 1Rod
- 2Barrel
- 3Piston
- 4Piston seal
- 5Rod seal
- 6Wiper
- 7Rod guide
- 8Head
- 9Cap
- 10Mounting eye
- 11Port A
- 12Port B
- 13Cap-end chamber
- 14Rod-end chamber
Main parts
- 01
Piston rod
Russian: шток
A steel bar attached to the piston that transmits force to the external mechanism. Ground and hard-chrome plated for wear and corrosion resistance.
- 02
Barrel (cylinder tube)
Russian: гильза
The main steel tube in which the piston moves. Its bore is precision-machined, usually honed, and must withstand pressure, mechanical loads and friction.
- 03
Piston
Russian: поршень
Moves inside the barrel and turns oil pressure into mechanical force. Piston seals stop oil passing from one chamber to the other.
- 04
Head and rod guide
Russian: передняя крышка, направляющая втулка
Keep the rod moving straight and hold the rod seal and the wiper.
- 05
Cap and mountings
Russian: задняя крышка, проушина
Close the rear of the barrel and attach the cylinder to the structure: eye, flange, clevis or trunnion.
- 06
Seals and wiper
Russian: уплотнения, грязесъёмник
Prevent external leaks and internal bypass between chambers. The wiper stops dust and dirt from being drawn in with the rod.
Other parts: rod nut, wear rings, oil ports and cushioning devices. Their set depends on the cylinder model and purpose.
How a hydraulic cylinder works
It works on hydraulic fluid pressure and the force that pressure creates on the piston area.
- 1Oil tank
- 2Pump
- 3Valve
- 4Cylinder
- 5Mechanism
- 6Pressure line
- 7Return line
- 1
The pump delivers oil under pressure
The hydraulic pump moves oil through the system. Pressure builds up from the load and the control elements.
- 2
The valve directs the flow
The directional control valve sends oil to the required chamber of the cylinder.
- 3
The piston moves
Pressurised oil pushes the piston, and the rod attached to it extends or retracts.
- 4
The mechanism moves
The rod’s motion lifts, lowers, pushes or pulls the machine’s working part.
In a double-acting cylinder oil is fed alternately to each side of the piston. Pressure on one side pushes the piston while oil from the other chamber returns to the tank. When the valve switches, the rod moves the other way.
Does your hydraulic cylinder need repair, or do you need a new one?
Send the machine model, main dimensions and a description of the fault — our specialist will contact you to agree on the scope of work and next steps.