The system pressure shown in the order code for pumps with pressure limiter and HPRV is a reflection of
the pressure limiter setting:
HPRVs are set at low flow condition. Any application or operating condition which leads to elevated HPRV
flow will cause a pressure rise with flow above the valve setting. Consult factory for application review.
Excessive operation of the HPRV will generate heat in the closed loop and may cause damage to the
internal components of the pump.
HPRV/Charge Check Valve Sectional View
HPRV and Charge Check Valve with Bypass Function
Relief mode
P003 268
Charging mode
P003 269
Charge Pressure Relief Valve (CPRV)
The charge pressure relief valve is a direct acting poppet valve that opens and discharges fluid to the
pump case when pressure exceeds a designated level. The charge pressure relief valve maintains charge
pressure at a designated level above case pressure.
This level is nominally set with the pump running at 1800 min
-1
(rpm), and with a fluid viscosity of 32
mm²/s [150 SUS]. In forward or reverse, charge pressure will be slightly lower than in neutral position. The
model code of the pump specifies the charge pressure relief valve setting. Typical charge pressure
increase from 1.2-1.5 bar per 10 l/min [17.4-21.8 psi per 2.64 US gal/min]. For external charge flow the
CPRV is set according to the table below:
CPRV flow setting for external charge supply
Tandem 045/053
Single 045/053
Single 060—165
Single 210/250/280
30 l/min [7.9 US gal/min]
15 l/min [3.9 US gal/min]
22.7 l/min [6.0 US gal/min]
40.0 l/min [10.6 US gal/min]
Charge pressure relief valve
Bypass Function
The HPRV valve also provides a loop bypass function when each of the two HPRV hex plugs are
mechanically backed out 3 full turns. Engaging the bypass function hydraulically connects both A & B
Service Manual
H1P 069—H1P 280 Axial Piston Single Pumps
Operation
©
Danfoss | January 2021
AX152886482551en-000601 | 13