Danfoss H1 Series, Основная информация

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Bearing loads and life
Bearing life is a function of speed, system pressure, charge pressure, and swashplate angle, plus any
external side or thrust loads. The influence of swashplate angle includes displacement as well as
direction. External loads are found in applications where the pump is driven with a side/thrust load (belt
or gear) as well as in installations with misalignment and improper concentricity between the pump and
drive coupling. All external side loads will act to reduce the normal bearing life of a pump. Other life
factors include oil type and viscosity.
In vehicle propel drives with no external shaft loads and where the system pressure and swashplate
angle are changing direction and magnitude regularly, the normal L
20
bearing life (80 % survival) will
exceed the hydraulic load-life of the unit.
In non propel drives such as vibratory drives, conveyor drives or fan drives, the operating speed and
pressure are often nearly constant and the swashplate angle is predominantly at maximum. These drives
have a distinctive duty cycle compared to a propulsion drive. In these types of applications a bearing life
review is recommended.
Applications with external shaft loads H1 pumps are designed with bearings that can accept some
external radial and thrust loads. When external loads are present, the allowable radial shaft loads are a
function of the load position relative to the mounting flange, the load orientation relative to the internal
loads, and the operating pressures of the hydraulic unit. In applications where external shaft loads cannot
be avoided, the impact on bearing life can be minimized by proper orientation of the load. Optimum
pump orientation is a consideration of the net loading on the shaft from the external load, the pump
rotating group and the charge pump load.
•
In applications where the pump is operated such that nearly equal amounts of forward vs. reverse
swashplate operation is experienced; bearing life can be optimized by orientating the external side
load at 0° or 180° such that the external side load acts 90° to the rotating group load (for details see
drawing below).
•
In applications where the pump is operated such that the swashplate is predominantly (> 75 %) on
one side of neutral (e.g. vibratory, conveyor, typical propel); bearing life can be optimized by
orientating the external side load generally opposite of the internal rotating group load. The direction
of internal loading is a function of rotation and system port, which has flow out. Tables are available
in the Controls section of each H1 size specific technical information that illustrates the flow out port
as a function of pump rotation and energized EDC solenoid.
•
H1 pumps are designed with bearings that can accept some thrust load such that incidental thrust
loads are of no consequence. When thrust loads are anticipated the allowable load will depend on
many factors and it is recommended that an application review be conducted.
Contact Danfoss for a bearing life review if external side loads are present.
Radial load position
P003 318E
L
270° R
e
R
e
M
e
180° R
e
90° R
e
0° R
e
M
e
= Shaft moment
L = Flange distance
R
e
= External force to the shaft
Allowable shaft loads and moments are shown for each size specific technical information.
Basic Information
H1 Axial Piston Pumps, Single and Tandem
System design parameters
32 | © Danfoss | April 2017 11062168 | BC00000057en-US0602