English 
Spanish 
Hydraulic Cylinder Design Manufacturing-Technical Foundation
1.2 Hydraulic Cylinder Parameters and Parameter Calculation
The previous article in this series discussed the Classification and Structure of Hydraulic Cylinders; today this article will explain Hydraulic Cylinder Parameters and Parameter Calculation.
1.2.1 Hydraulic Cylinder Parameters and Main Parameters
The basic parameters of hydraulic cylinders shall include cylinder bore diameter, piston rod diameter (outer) diameter, nominal pressure, stroke, and installation dimensions.
In addition to the basic parameters of hydraulic cylinders, other standards related to hydraulic cylinders also include thrust and pull forces at nominal pressure, piston speed, rated pressure, minimum piston rod diameter (outer) diameter, plunger diameter for plunger-type hydraulic cylinders, limit or maximum stroke, ratio of two-chamber area, threaded oil ports and nominal port diameter, piston rod thread type and size, mass, installation type, and connection dimensions.
1.2.2 Hydraulic Cylinder Parameter Calculation Formula
(1) Cylinder Theoretical Output Force Calculation Formula
① Double-acting single-piston rod hydraulic cylinder. The thrust push force calculation formula is
The calculation formula for the pulling force of a double-acting single-piston-rod hydraulic cylinder is:
② Single-acting plunger hydraulic cylinder. The thrust calculation formula is:
Formulas (1–3) are applicable to plunger cylinders as well as to double-acting single-rod hydraulic cylinders used in differential circuits, for calculating the theoretical output thrust of the hydraulic cylinder.
Note: the“theoretical output force” refers to the theoretical output thrust of the cylinder at (or within the range of) a rated pressure that includes a nominal pressure value. Strictly speaking, if the above formulas are calculated using the nominal pressure, then they should represent the theoretical output force of the cylinder at this specific nominal pressure value.
(2) Calculation Formula for Cylinder Motion Resistance
The actual output force of the cylinder is smaller than the theoretical output force, because in the theoretical calculation, the effects of back pressure, frictional resistance, and leakage are ignored.
(3) Calculation Formula for Cylinder Operating Speed
① Double-acting single-rod hydraulic cylinder
② Single-acting plunger hydraulic cylinder
(4) Calculation formula for reciprocating speed ratio of double-acting single-piston-rod hydraulic cylinder
Note: 1. The reciprocating speed ratio of a hydraulic cylinder is not a hydraulic cylinder parameter. In all versions of this manual, the speed ratio is defined as
, meaning the speed ratio is equal to the ratio of the two chamber areas. The speed ratio itself and the scientific nature of this definition are debatable. Here, the speed ratio is defined as
Please note this.
2. The standard “Two-Cavity Area Ratio of Single-Piston-Rod Hydraulic Cylinders” specifies the standard value for the two-cavity area ratio of single-piston-rod hydraulic cylinders.
(5) Calculation formula for cylinder full stroke time
① Full Stroke Time of a Double-Acting Single-Rod Hydraulic Cylinder
②Full Stroke Time of a Single-Acting Plunger Hydraulic Cylinder
(6) Calculation formula for theoretical output work and power of hydraulic cylinder
(7) Cylinder output force efficiency calculation formula
(8) Cylinder efficiency calculation formula
