Cylinder; A.3.2 Cylinder - Siemens SINAMICS S120 System Manual

Appendix
A.3 Hydraulic
A.3.2

Cylinder

General
The cylinder acts as the drive element in the electro-hydraulic control loop.
It converts the flow rate into linear motion. In this case, high velocities are required for rapid
traverse movements as well as slow velocities for machining operations.
Synchronizing or differential cylinder
For a synchronizing cylinder, a piston rod with the same diameter is mounted at both ends to
transmit the force. Consequently, the piston areas at the A and B sides are identical.
Likewise, at a constant piston speed, the incoming flow is equal to the displaced flow in the
settled state. As a consequence, the synchronizing cylinder acts symmetrically when
extending and retracting.
In contrast to the synchronizing cylinder, a differential cylinder has either a piston rod to
transfer the force at one end only — or the piston rods have different diameters.
Consequently, the piston areas at the A and B sides are different. Furthermore, at a constant
piston velocity, the displaced flow rate is not the same as the incoming flow rate. The
maximum extension and retraction velocities are not the same for a differential cylinder.
However, at the HLA module this can be compensated using the "Plane adaptation" (p0211)
function.
Apart from the piston diameter, it is necessary to specify the rod diameters at the A and B
sides. For a differential cylinder, both rod diameters are different, one of the rods might even
have a zero diameter. The maximum piston stroke and cylinder dead volume are also
required.
Figure A-19
252
Cylinder principle
System Manual, 04/2015, 6SL3097-4BA00-0BP1
Hydraulic Drive