This symbol is complete in showing the main poppet (low pressure, high volume relief), the pilot relief (high pressure, low volume), the orifices which establish pressure decay in the pilot circuit, and the solenoid valve for venting. In common practice, the industry does not use symbols of this complexity. Over the years, it has become standard practice to represent both pilot operated and direct operated reliefs with the simpler direct operated relief valve symbol. This, however, often leads to confusion, since the total function cannot be represented in this manner. Rexroth has developed and will be promoting the use of a new simplified symbol for representing pilot operated reliefs.
The following are variations showing this simplified symbol with various uses of the pilot circuit:
Tuesday, April 30, 2013 12:28