Fluid Selection; Case Drain; Independent Braking System; Bearing Loads And Life - Danfoss H1 Series Technical Information

Technical Information
H1 Bent Axis Variable Displacement Motors, Size 060/080/110/160/210/250
System design parameters

Fluid selection

Case drain

Independent braking system

Bearing loads and life

Shaft torque

© Danfoss | December 2016
Ratings and performance data are based on operating with hydraulic fluids containing oxidation, rust
and foam inhibitors. These fluids must possess good thermal and hydrolytic stability to prevent wear,
erosion, and corrosion of motor components.
C
Caution
Never mix hydraulic fluids of different types.
Fire resistant fluids are also suitable at modified operating conditions. For more information, see
Hydraulic Fluids and Lubricants, Technical Information BC00000093.
A case drain line must be connected to the case outlets of each motor to return the internal leakage oil to
the system reservoir. When filling the case before start up, use the highest case drain outlet to promote
complete filling of the case. The case drain fluid is typically the hottest fluid in the system. It is highly
recommended to route the case drain flow through a heat exchanger before it is returned to the
reservoir.
In some applications, it may be required the use of additional cross-flushing of the motor. If the motor is
used mainly in a high speed application, higher cooling requirements may be needed for the rotating kit
and tapered roller bearings. Use the lowest case drain port as the inlet port and the highest case drain
port as the outlet port. This will ensure that the case is full of oil at all times.
Apply unit case pressure ratings to case drain routing and design.
W
Warning
Unintended vehicle or machine movement hazard
Exceeding maximum speed may cause a loss of hydrostatic drive line power and braking capacity. You
must provide a braking system, redundant to the hydrostatic transmission, sufficient to stop and hold the
vehicle or machine in the event of hydrostatic drive power loss. The braking system must also be
suffivient to hold the machine in place when full power is applied.
Bearing life is a function of speed, system pressure, motor angle and any external side or thrust loads. The
influence of motor angle includes displacement as well as direction. External side loads are found in some
applications such as a helical gear without its own support bearings, installed directly on to the motor
shaft. All external side loads will act to reduce the normal bearing life of the motor. Other life factors
include oil type and viscosity.
When external side 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. Optimal motor orientation is a
consideration of the net loading on the shaft from the external load and the motor rotating kit.
Contact Danfoss for a bearing life review if external side loads and thrust loads are present.
Available shafts are capable to transmit the maximum torque capability at maximum working pressure.
Lubrication or similar treatment of splined motor shaft is recommended for proper torque transmission.
For more information, see Lubrication of Splined Shafts, Technical Information L1310978.
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