grippers & rack and pinion rotary actuators - Industrial and Bearing ...

RACK AND PINIONROTARY ACTUATORSSELECTIONTo select a rack and pinion rotaryactuator, the following applicationdata is required:• Torque required to rotate the load.• Degree of rotation.• Pressure available (PSI).• Radial and/or thrust loads.Refer to the performance charts onpage 21 to determine the followingselection specifications.1.DETERMINE TORQUEOUTPUT AT AVAILABLEPRESSURERefer to the Torque vs Pressure chartand choose a rotary actuator based on itstorque output at the available operatingpressure that will rotate the load.2.DETERMINE ACTUATORSBEARING LOADCAPACITYConsult the Bearing Load Capacitychart. Bearing loads must not exceedthe values shown for radial and/orthrust loading.3.CALCULATE KINETICENERGY IF APPLICABLEKinetic energy comes into play if theactuator will decelerate the load. Inthese applications, both torque output torotate the load and kinetic energyabsorption to stop the load must beconsidered to correctly size a rotaryactuator.Once the KE value per stop has beencalculated, refer to the Rotary ActuatorKinetic Energy Rating chart anddetermine if standard adjustable stopswith bumpers are adequate or if optionalcushions or shock absorbers will berequired.How to calculate kinetic energy isshown below.KINETIC ENERGY CALCULATION1 2KE = Jmω2angle traveled (deg.)ω = 0.035 ×rotation time (sec.)whereKE = Kinetic Energy per stop ( in. −lbs.)Jm= Rotational mass moment of2inertia ( in. −lbs−sec. )ω = Peak Velocity ( rad. / sec.)( assuming twice averagevelocity)W = Weight of load ( lbs.)g = Gravitational cons tant=2386. 4 in. / sec.k = Radius of gyration ( in.)MOMENTS OF INERTIA EXAMPLESSLENDER ROD MOUNTEDOFF CENTERTHIN DISK MOUNTED ON CENTERTHIN RECTANGULAR PLATEMOUNTED OFF CENTERabkabcW 1W 2POINT LOAD2W kJ = mg× 2W 1W 222W1a W2bJm = × + ×g 3 g 32 2W W14a + c W24b+ cJm = × + ×g 12 g 12kWJm = × k2g2 220