1 Basic Motor Operating Principle • Sauer Danfoss LSHT motors are fixed displacement, high torque motors. – For a given oil flow and pressure, the displacement determines the torque and speed – For a given displacement, the oil flow rate determines the speed, and the pressure determines the torque MENU
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1
Basic
Motor Operating Principle
• Sauer Danfoss LSHT motors are fixed displacement, high torque motors.
– For a given oil flow and pressure, the displacement determines the torque and speed
– For a given displacement,
the oil flow rate determines
the speed, and the pressure
determines the torque
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0 10 20 30 40 50 60 70 80
OML
OMM
OMP / DH
OMR / DS
OMH
OMEW
OMS
OMT
OMV
TMK
TMT
TMV
KW
Basic
Motor Program
Mini Motors
Medium-sizedMotors
Large Motors
O – series
Large Motors
T- series
Large
Small
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• Hydraulic energy (flow/pressure) is translated into mechanical energy by means of a gearwheel set, cardan shaft, andoutput shaft.
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Basic
Motor Operating Principle
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Basic
The Gearwheel Set
• The Gearwheel set consists of two parts
1. External rim (rollers)
• Integral part of motor housing
2. Internal gearwheel
• Rotates within the rim and orbits around the center
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Basic
The Cardan Shaft
• The cardan shaft transmits the torque from the gearwheel shaft to the output shaft
• The cardan shaft design allows the cardan shaft centerline to orbit with the eccentricity of the gear set
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Basic
The Output Shaft
• The output shaft transmits the torque to the application.
• The output shaft and bearings also bear the radial load
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Basic
How does it work?
• A valve is needed to meter flow into and out of the chambers in the gear wheel.
• Sauer Danfoss motors utilize one of two types of valves
– Spool valve
– Disc Valve
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Basic
How does it work?
• Spool Valve– The spool valve is integrated into the shaft
– The cardan shaft therefore serves two purposes—to transmit torque, and to rotate the valve
– This design results in a compact motor with few rotating parts
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Basic
How does it work?
• Disc Valve
– Distributor valve separated from the output shaft and driven by a separate cardan shaft
– A balance plate counterbalances the forces around the distributor valve minimizing volumetric and mechanical losses
– This design results in precise valve function with high volumetric efficiency at all pressures
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Overview
Main types
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Selection
Application Considerations
• Geroller vs. Gerotor
• Spool Valve vs. Disc Valve
• Bearing Capacity / Shaft Strength
• Shaft Seal Considerations
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Selection
Geroller vs. Gerotor
– Advantages of Geroller motor• Smoother running
• Better efficiency (and more consistent efficiency over life of motor)
• Better life
– Particularly in applications with many starts/stops/reversals
– Advantages of Gerotor motor• Cost !
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– Advantages of Disc Valve• Higher volumetric efficiency
– Steady speed at lower flows
• No timing error due to deflection in main cardan shaft