Since actual fluids are compressible, they behave like a spring when pressure is applied to them: the higher the pressure, the more they are compressed and the smaller their volume becomes.
The spring stiffness c öl is derived as follows:
where A = cross section of the transverse column
E öl = modulus of elasticity of oil
V o = volume under pressure
As a result, the spring stiffness is highly dependent on the area and the length of the column of oil (Figure H 17).
For the synchronizing cylinder, c öl is derived as follows:
For the hydraulically fixed differential cylinder, we get:
For the fixed hydraulic motor, we get:
where V 2 = displacement of the motor
V o = dead volume for one side
Figure H 17: Spring stiffness depending on piston area and oil column length