Hydraulic MotorsBrought to you by:Demetri PreonasGreg Unverferth

Overview of LessonHow they workTypes of MotorsPerformanceApplications

How a hydraulic motor worksHigh 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.

Types of Hydraulic MotorsGear MotorsVane MotorsPiston MotorsLimited Rotation Actuator

Gear MotorsExternal Gear Motor2 rotating gears, the area of the gear teeth is where the pressure acts to create forceBoth gears turn simultaneouslyOne gear is connected to the output shaft and the other is an idler.Model 21300 B1 Series Gear MotorEaton Heavy Duty Series 1 Variable Motor

Gear MotorsInternal Gear MotorsTwo categoriesDirect 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

Vane MotorsSpring loaded vanes are connected to a rotorThe 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.

Piston MotorsMany different types of piston motorsAll of them use the same basic principlesMuch like a cylinder, only turns a shaft like the cylinders in your car engine.Generally the most efficientHigh power, high speed, high pressure

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

In-line Piston MotorsSimple constructionLow costUsed in low torque high speed applications, such as machine tools

Radial Piston MotorsHigh TorqueLow speedPossible application could be a roller.

Bent Axis Piston MotorIs one example of variable displacement motor.The angle is altered to change the displacement.

Limited Rotation ActuatorAlso sometimes called a oscillator.Has limited movement High torque

PerformanceEfficiencyTwo factorsInternal leakageVolumetric efficiency and speed decrease due to leakage.Internal frictionMechanical efficiency loss due to torque lossEffv= (rpmact/rpmtheo) * 100Effv= volumetric efficiency

Effm= (Tact/Ttheo) * 100Effm= Mechanical efficiency

Effoa=(Effv/100)*(Effm/100)*100Effoa= Over All Efficiency

PerformanceThe 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

PowerHpout= (Tlb-ft * rpm)/5252

Effoa= (Hpout * 100)/ Hpin

You just learned:How a hydraulic motor works The basics of the different types of motorsSome possible applications for hydraulic motorsHow to calculate powerHow to find efficiency

DemetriDemetriGregGregThe 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 158DemetriDemitriFigure 7-23 on page 159 and a better stepped progression picture in figure 7-23 on page 160 two cutaway pictures on page 161DemetriDemetriFigures 7-27 through 7-29 on pages 162 and 163Greg

GregGregGregFigure 7-31 on page 165DemetriDemetriFigure 7-34 on page 166Demetri

DemetriFigure 7-37,38 pages 168, 169Greg

GregFigure 7-38 page 170GregGregFigure 7-16 on page 152DemetriDemetriDemetriDemetriDemetriGregGregDemetri