Input Speed
Minimum
speed
is the lowest input speed recommended during engine idle condition. Operating below
minimum speed limits the pump’s ability to maintain adequate flow for lubrication and
power transmission.
Rated speed
is the highest input speed recommended at full power condition. Operating at or
below this speed should yield satisfactory product life.
Operating conditions between rated and maximum speed should be restricted to less
than full power and to limited periods of time.
Maximum
speed
is the highest operating speed permitted. Exceeding maximum speed reduces product
life and can cause loss of hydrostatic power and braking capacity. For most drive
systems, maximum unit speed occurs during downhill braking or negative power
conditions.
W
Warning
Never exceed the maximum speed limit under any operating conditions.
During hydraulic braking and downhill conditions, the prime mover must be capable of providing
sufficient braking torque in order to avoid pump over speed. This is especially important to consider for
turbo-charged and Tier 4 engines.
For more information please see
Pressure and Speed Limits
, BC152886484313, when determining speed
limits for a particular application.
System Pressure
Hydraulic unit life depends on the speed and normal operating — or weighted average — pressure that
can only be determined from a duty cycle analysis.
System pressure is the differential pressure between high pressure system ports. It is the dominant
operating variable affecting hydraulic unit life. High system pressure, which results
from high load, reduces expected life.
Application
pressure
is the high pressure relief or pressure limiter setting normally defined within the
order code of the pump. This is the applied system pressure at which the drive line
generates the maximum calculated pull or torque in the application.
Maximum
working
pressure
is the highest recommended application pressure and is not intended to be a
continuous pressure. Propel systems with application pressures at, or below this
pressure should yield satisfactory unit life given proper component sizing.
Application pressures above maximum working pressure will only be considered
with duty cycle analysis and factory approval.
Pressure spikes are normal and must be considered when reviewing maximum
working pressure.
Maximum
pressure
is the highest intermittent pressure allowed under any circumstances. Applications
with applied pressures between rated and maximum require factory approval with
complete application, duty cycle, and life expectancy analysis.
Minimum low
loop pressure
must be maintained under all operating conditions to avoid cavitation.
All pressure limits are differential pressures referenced to low loop (charge) pressure.
Subtract low loop pressure from gauge readings to compute the differential.
Service Manual
H1P 069—H1P 250 Axial Piston Single Pumps
Operating Parameters
©
Danfoss | September 2020
AX152886482551en-000504 | 19
