1. Brought to you by: Demetri Preonas Greg Unverferth
Hydraulic Motors
Brought to you by:
Demetri Preonas
Greg Unverferth
Demetri

2. Overview of Lesson How they work Types of Motors Performance
Applications
Demetri

3. How a hydraulic motor works
High pressure fluid is used to turn a shaft.
This is done in many different ways.
Much like a cylinder the power comes from the pressure acting over a large area and creating a large force.
Greg

4. Types of Hydraulic Motors
Gear Motors
Vane Motors
Piston Motors
Limited Rotation Actuator
Greg

5. Gear Motors External Gear Motor
2 rotating gears, the area of the gear teeth is where the pressure acts to create force
Both gears turn simultaneously
One gear is connected to the output shaft and the other is an idler.
Model “B1 Series” Gear Motor
Eaton® Heavy Duty Series 1 Variable Motor
The two gears are enclosed in a housing. Close tolerances between the gear teeth and the housing help to prevent fluid leakage and increase volumetric efficiency. FIGURE 7-21 on page 158
Demetri

6. Demitri

7. Gear Motors Internal Gear Motors Two categories
Direct drive gerotor, works much like a rotary engine.
Two gears, an inner and an outer.
The pressure pushes them around a center point, turning a shaft
Figure 7-23 on page 159 and a better stepped progression picture in figure 7-23 on page 160 two cutaway pictures on page 161
Demetri

9. Demetri

10. Vane Motors Spring loaded vanes are connected to a rotor
The rotor turns inside a cam ring (elliptical hole)
The vanes slide in and out of the slots in the rotor to make contact with the cam wall.
Figures 7-27 through 7-29 on pages 162 and 163
Greg

11. Greg

12. Piston Motors Many different types of piston motors
All of them use the same basic principles
Much like a cylinder, only turns a shaft like the cylinders in your car engine.
Generally the most efficient
High power, high speed, high pressure
Greg

13. Piston Motors Most efficient
Often used in aerospace applications due to high power to weight ratio
Greg

14. In-line Piston Motors Simple construction Low cost
Used in low torque high speed applications, such as machine tools
Figure 7-31 on page 165
Demetri

15. Demetri

16. Radial Piston Motors High Torque Low speed
Possible application could be a roller.
Figure 7-34 on page 166
Demetri

17. Demetri

18. Bent Axis Piston Motor Is one example of variable displacement motor.
The angle is altered to change the displacement.
Figure 7-37,38 pages 168, 169
Greg

19. Greg

20. Limited Rotation Actuator
Also sometimes called a oscillator.
Has limited movement
High torque
Figure 7-38 page 170
Greg

21. Greg

22. Performance Efficiency Two factors Internal leakage Internal friction
Volumetric efficiency and speed decrease due to leakage.
Internal friction
Mechanical efficiency loss due to torque loss
Effv= (rpmact/rpmtheo) * 100
Effv= volumetric efficiency
Effm= (Tact/Ttheo) * 100
Effm= Mechanical efficiency
Effoa=(Effv/100)*(Effm/100)*100
Effoa= Over All Efficiency
Figure 7-16 on page 152
Demetri

23. Demetri

24. Demetri

25. Performance
The mechanical torque desired must be specified in order to find required working pressure.
Pin= (T*2)/Disp.
The rpm desired must be specified in order to find required flow rate.
Q= (rpm * Disp.)/231
Demetri

26. Demetri

27. Power
Hpout= (Tlb-ft * rpm)/5252
Effoa= (Hpout * 100)/ Hpin
Greg

28. Greg

29. You just learned: How a hydraulic motor works
The basics of the different types of motors
Some possible applications for hydraulic motors
How to calculate power
How to find efficiency
Demetri