hydraulic actuators ppt

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5/26/2018 HydraulicActuatorsPpt-slidepdf.com http://slidepdf.com/reader/full/hydraulic-actuators-ppt 1/29 2005/2006 I. Hydraulic and Pneumatic Systems 1  Hydraulic actuators: cylinders Cylinder types: Single acting: work can be done only in one direction Piston Double acting piston: Piston rod on both sides Plunger Work is done in both directions Telescopic Telescopic Fast moving Tandem Fast moving

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  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic actuators: cylindersCylinder types:Single acting: work can be done only in one directionPistonDouble acting piston:Piston rod on both sidesPlungerWork is done in both directionsTelescopicTelescopicFast movingTandemFast moving

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersHydraulic cylinderHidraulikus munkahengerekRgztplcs kivitel 1.Rgztplcs hidraulika henger, a hengerfejen tallhat karims rgztssel

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersHydraulic cylinderHidraulikus munkahengerekHengeres kivitel 1.Hengeres ptsi mddal kszlt hidraulika henger

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersProperties:The cylinders have to be good quality steel with close tolerances.There have to be good sealing both at the piston rod and at the cylinder.With time dirt may come in and damage the surfaces. This has to be possibly reduced.In this case, the leakage will increase all the time.

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCalculation of cylindersfriction forcesinertial forcesmaximum loadslow motion, can be often neglectedBackward:Outward:

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCalculation of cylindersHydraulic cylinders should be possibly operated in the 3rd region for smooth operation.If the cylinder is new, the leakage losses are negligibly small so that:c = mechStick-slipTransitionNormal behaviourat higher pressures

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersChecking for bucklingn: safety factor: 1-3,5lk: buckling lengthI1: moment of inertia of the piston rodE: elasticity modulus of the rod materialMaximum permissible force:

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCushioning of cylinders:A hard impact of the piston at the end surfaces has to be inhibited kinetic energy has to be absorbed.This is done by increasing the hydraulic resistance at the end of the stroke.

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsSwivel vane rotary actuator:Limited angle in both directionsMaximum angle always smaller than 360The same torque in both directionsPiston rotary actuator:With rack and gear couplingHere maximum angle may be larger than 360Mindkt irnyban azonosan mkd hengerrel s fogaslces meghajtssal mkdtetett toldugattys lenghajtsPrhuzamdugattys lenghajtsForgdugattys lenghajts menettel mkdtetett meghajtcsappalLimited angle rotary actuatorLimited angle rotary actuatorParallel piston rotary actuator??????

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Big picturesEnd of normal presentationBeginning of big pictures

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: plungersmaller force, better efficiency, axial support is necessary but cylinder does not have to be so good qualityWithout inner bufferWith inner buffer (pilot piston)

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: piston, single acting, pressing-cylinderSpringinsideoutside

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: piston, single acting, pullerSpringinsideoutside

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: piston, double actingVelocity is different

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: piston, double actingPiston rod on both sideVelocity is the same in both directions

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: piston, double actingPiston rod on both sideVelocity is different in the two directions depending on cross section ratio of the rods

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: double acting piston, tandem

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: single acting, fast moving

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: double acting, fast moving

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: telescopic, single actingLarge working paths or limited space

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCylinder types: telescopic, double actingLarge working paths or limited space

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersChecking for buckling:Eulers casesPictureFree buckling lengthManner of end fixing

    Note1. Case

    One end freeOne end fixedOr trunnion at endmounting stylemounting stylemounting style2. Case

    Two ends pivoted and guided

    3. Case

    One end guided and pivoted, other end fixed4. Case

    Two ends fixed and guided

    mounting style

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Hydraulic cylindersCushioning of cylinders:PistonCushion noseCylinder capStroke volumeCushion orificeThrottleCushion adjustment screwMotherNon-return valveGas valve

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsParallel piston rotary actuator

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuators???

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsRack-and-pinion piston-type rotary actuator:

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsLimited angle rotary actuator:

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsLimited angle rotary actuator:

    Hydraulic and Pneumatic Systems

  • 2005/2006 I.Hydraulic and Pneumatic Systems*Rotary hydraulic actuatorsHelix actuator:

    Hydraulic and Pneumatic Systems

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