Danfoss PVG 16 Service Manual

Also see for PVG 16 PVH/Covers: Service and parts manual Technical information Installation guide

Contents

Danfoss PVG 16 Service Manual Manual pdf 11 page image

Open center PVPDescription of the example: PVG 32 with open center PVP (fixed displacement pump) and PVB with flowcontrol spool.When the pump is started and the main spools in the individual basic modules (11) are in the neutralposition, oil flows from the pump, through connection P, across the pressure adjustment spool (6) totank. The oil flow led across the pressure adjustment spool determines the pump pressure (stand-bypressure).When one or more of the main spools are actuated, the highest load pressure is fed through the shuttlevalve circuit (10) to the spring chamber behind the pressure adjustment spool (6), and completely orpartially closes the connection to tank to maintain pump pressure. Pump pressure is applied to the right-hand side of the pressure adjustment spool.The pressure relief valve (1) will open when the load pressure exceed the set value, diverting pump flowback to tank.In a pressure-compensated basic module the compensator (14) maintains a constant pressure dropacross the main spool – both when the load changes and when a module with a higher load pressure isactuated.With a non pressure-compensated basic module incorporating a load drop check valve (18) in channel P,the check valve prevents return oil flow.The basic module can be supplied without the load drop check valve in channel P for functions with over-center valves.The shock valves PVLP (13) with fixed setting and the suction valves PVLA (17) on ports A and B are usedfor the protection of the individual working function against overload and/or cavitation.An adjustable LS pressure limiting valve (12) can be built into the A and B ports of pressure-compensatedbasic modules to limit the pressure from the individual working functions. The LS pressure limiting valvessave energy compared with:• PVLP all the oil flow to the working function will be led across the combined shock and suction valvesto tank if the pressure exceeds the fixed setting.• LS pressure limiting valves an oil flow of about 2 l/min [0.5 US gal/min] will be led across the LSpressure limiting valve to tank if the pressure exceeds the valve setting.Please see the sectional drawing Sectional view on page 12 for better understanding of this example.Closed center PVPDescription of the example: PVG 32 with closed center PVP (variable displacement pump) and PVB withflow control spool.In the closed center version of PVP an orifice (5) and a plug (7) have been fitted instead of the plug (4).This means that the pressure adjustment spool (6) will open to tank when the pressure in channel Pexceeds the set value of the pressure relief valve (1). The pressure relief valve in PVP should be set at apressure of approx. 30 bar [435 psi] above maximum system pressure (set on the pump or externalpressure relief valve).In load sensing systems the load pressure is led to the pump control via the LS connection (8). In theneutral position the pump load sense control sets the displacement so that leakage in the system iscompensated, to maintain the set stand-by pressure. When a main spool is actuated the pump load sensecontrol will adjust the displacement so that the set differential pressure (margin) between P and LS ismaintained.Please see the sectional drawing Sectional view on page 12 for better understanding of this example.Service ManualPVG 16 and 32 Service Assembly/Disassembly GuideGeneral information© Danfoss | November 2017 L1104530 | AX00000133en-US0106 | 11