Danfoss H1 Series, Основная информация

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Pressure limiter valves
Pressure limiter valves provide system pressure protection by compensating the pump swashplate
position when the set pressure of the valve is reached. A pressure limiter is a non-dissipative (non heat
generating) pressure regulating system.
Each side of the transmission loop has a dedicated pressure limiter valve that is set independently. A
pump configured with pressure limiter must have pressure limiters on both sides of the system pressure
loop. The pump order code allows for different pressure settings to be used at each system port.
The pressure limiter setting is the differential pressure between the high and low loops. When the
pressure limiter setting is reached, the valve ports oil to the low-pressure side of the servo piston. The
change in servo differential pressure rapidly reduces pump displacement. Fluid flow from the valve
continues until the resulting drop in pump displacement causes system pressure to fall below the
pressure limiter setting.
An active pressure limiter destrokes a pump to near neutral when the load is in a stalled condition. The
pump swashplate moves in either direction necessary to regulate the system pressure, including into
stroke (overrunning) or over-center (winch payout).
The pressure limiter is optional for H1 single pumps and not available for tandem pumps.
High Pressure Relief Valve (HPRV) and charge check
All H1 pumps are equipped with a combination high pressure relief and charge check valve. The high-
pressure relief function is a dissipative (with heat generation) pressure control valve for the purpose of
limiting excessive system pressures. The charge check function acts to replenish the low-pressure side of
the working loop with charge oil. Each side of the transmission loop has a dedicated HPRV valve that is
non-adjustable with a factory set pressure. When system pressure exceeds the factory setting of the
valve, oil is passed from the high pressure system loop, into the charge gallery, and into the low pressure
system loop via the charge check.
The pump order code allows for different pressure settings to be used at each system port. When a HPRV
valve is used in conjunction with a pressure limiter, the HPRV valve is always factory set above the setting
of the pressure limiter. The system pressure order code for pumps with only HPRV is a reflection of the
HPRV setting.
The system pressure order code for pumps configured with pressure limiter and HPRV is a reflection of
the pressure limiter setting.
HPRV´s are factory set at a low flow condition. Any application or operating condition which leads to
elevated HPRV flow will cause a pressure rise with flow above a 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.
Basic Information
H1 Axial Piston Pumps, Single and Tandem
Operation
© Danfoss | April 2017 11062168 | BC00000057en-US0602 | 7