Danfoss PVG 32 Application Guide

A PC spool works as a variable orifice controlling flow P>A/B and A/B>T, like an FC spool, and also
controls LS>T. See the concept in Basic principle of a PC spool on page 7.
Basic principle of a PC spool
The Pc has a connection to the tank through a fixed orifice in series with a variable orifice (controlled by
spool displacement). This means that the LS signal is manipulated by the variable orifice. See the
characteristics of a PC spool in PC spool on page 7.
PC spool
Adrain variable connection from Pc to tank (manipulates the LS signal)
A(pc->Pl) physical opening area of the spool as a function of its position
Pl load pressure
Pc manipulated LS pressure + spring pressure
Ql flow out of the valve
The example in PC spool on page 7 shows a Ql curve, which is the flow out of the valve. Flow starts when a
pressure drop across the spool exist. So in this example, the flow will start and increase when Pc gets
higher than Pl. As a result, the spool deadband varies as the size of the load changes.
So for PC spools a certain position of the main spool is proportional to a certain Pc pressure.
Application Guide
Using flow or pressure control spools
Functionality of a pressure control spool
©
Danfoss | Feb 2017 AB00000079en-US0101 | 7

Danfoss PVG 32 Specifications

General

Category	Control Unit
Maximum working pressure	350 bar
Size	32
Type	Proportional Valve
Maximum operating pressure	420 bar
Porting pattern	ISO 4401
Electrical connection	AMP