The VW 22/18 M5-03 valve block for the open circuit has a  modular system with five sections plus a pressure release section  comprising the basic set-up. Three additional sections can be added on  each side of the block, thus specifically addressing customer needs. 
Various  functions can be selected for the additional sections, which are  perfectly designed for the requirements in a wheeled excavator. Options  such as boom- or lift- regeneration, anti-drift and return flow bypass  are available, as are rod-to-head-regeneration and an innovative float  function for the excavator for the first time. 
In conventional  control valves, the actuator is fixed. In certain applications, it is  desired that a cylinder yields to external forces by being able to  retract and extend     —    the so-called floating function. This is  particularly important when either increased wear of the attachment on a  hard surface or damage to a sensitive surface by the attachment is to  be avoided. The control valve is available in two nominal sizes: nominal  size 18 with a max. flow rate of 250 l/min and size 22, which allows a  max. flow rate of 350 l/min. 
Linde Hydraulics