Danfoss H1 Service Manual

Also see for H1 Series: Technical information Technical information Technical information Technical information Technical information

Contents

OverviewThis section defines input speed and pressure operating parameters and limitations for H1 pumps. Foractual parameters, refer to the technical specifications for each displacement.Input speedMinimum speed is the lowest input speed recommended during engine idle condition. Operating belowminimum speed limits the pump's ability to maintain adequate flow for lubrication and powertransmission.Rated speed is the highest input speed recommended at full power. Operating at or below this speedgenerally yields satisfactory product life.Maximum speed is the highest operating speed permitted. Exceeding maximum speed reduces productlife and can cause loss of hydrostatic power and braking capacity. Never exceed the maximum speedlimit under any operating conditions.When determining speed limits for a particular application see Danfoss publication BLN-9884 Pressureand speed limits.W WarningUnintended vehicle or machine movement hazardExceeding maximum speed may cause a loss of hydrostatic drive line power and braking capacity. Youmust provide a braking system, redundant to the hydrostatic transmission, sufficient to stop and hold thevehicle or machine in the event of hydrostatic drive power loss.System pressureSystem pressure is the differential pressure between system ports A & B and/or C & D. It is the dominantoperating variable affecting hydraulic unit life. High system pressure, which results from high load,reduces expected life. Hydraulic unit life depends on speed and normal operating—or weighted average—pressure that you can only determine from a duty cycle analysis.Applied pressure is the chosen application pressure in the order code for the pump. This is the pressureat which the drive line generates maximum pull or torque in the application.Rated pressure is the design pressure for the pump. Applications with applied pressures at or below thispressure should yield satisfactory unit life given proper component selection.Maximum pressure (peak) is the highest intermittent pressure allowed under any circumstances.Applications with applied pressures between rated and maximum require factory approval withcomplete application, duty cycle, and life expectancy analysis.All pressure limits are differential pressures referenced to low loop (charge) pressure. Subtract low looppressure from gauge readings to compute the differential.Charge pressureThe external charge pump supplies the control with pressure to operate the servo piston and to maintaina minimum pressure in the low side of the transmission loop. An internal charge relief valve regulatespressure in the charge circuit.Minimum charge pressure is the lowest pressure safe working conditions allow in the system loop.Minimum control pressure requirements are a function of speed, pressure, and swashplate angle, andmay be higher than the minimum charge pressure shown in the technical specifications.Maximum charge pressure is the highest charge pressure the charge relief adjustment allows, andwhich provides normal component life. You can use elevated charge pressure as a secondary means toreduce swashplate response time.Service ManualH1 45/53/60/68 Tandem Closed Circuit Axial Piston PumpsOperating parameters20 | © Danfoss | June 2018 520L0928 | AX00000103en-US0303