P1V-M Robust Air Motors - Duncan Rogers

Robust air motorsTheoretical calculationsThis section provides you with the background you need inorder to select the right air motor for common applications.The first four parts explain the direct physical relationshipsbetween:Force - Torque - Speed - Power RequirementBefore selecting an air motor, you need to know the torquerequired by the application at the necessary speed. Sometimes,the torque and the speed are not known but the power requirementand the speed of movement are. You can use the followingformulas to calculate the speed and torque.PowerThe power requirement is always calculated in N.Formula:F = m x gF = power in Nm = mass in kgg = gravitation (9,81) in m/s 2In this example, the mass is 150 kgF = 150 x 9,81 NF = 1470 NTorqueTorque is the force applied to produce rotational motion (rotationalforce) or the force applied in the opposite direction. It isthe product of the rotational force F and the distance from thepivot point (radius or moment arm)Formula:M = m x g x rM = torque in Nmm = mass in kgg = gravitation (9,81) in m/s 2r = radius or moment arm in mrF150 kgM150 kgP1V-MSpeedThe required motor speed can be calculated if the speed ofmovement and the radius (diameter) are known.n = v x 60/(2 x π x r)n = motor speed in rpmv = speed of movement in m/secr = radius in mπ = constant (3,14)In this example, the speed of movement is 1,5 m/sand the drum diameter is 300 m (radius r = 0,15 m)n = 1,5 x 60/(2 x π x 0,15) rpmn = 96 rpmPower RequirementThe power requirement can be calculated if the motor speedand torque are known.P = M x n/9550P = power in kWM = torque in Nmn = rpm9550 = conversion factorIn this example, a torque of 1,25 Nm is requiredat a speed of 1500 rpm.P = 1,25 x 1500/9550P = 0,196 kW or approx. 200 WattrvnM, nIn this example, the drum diameter is 300 mm, whichmeans the radius r = 0,15 m, and the mass is 150kg.M = 150 x 9,81 x 0,15 NmM = 221 Nm22Parker Hannifin CorporationPneumatic Division - Europe