Hi, I would appreciate if someone can help me figure out this design problem. I am working on designing a device to pull plants from the soil. This device consisting of two steel solid core rubber coated rollers. The rollers will be positioned facing each other and rotates in a way to pull plants upright. The rollers dimensions are 12in length, 2.5in diameter, weight is 6lbs, and the rubber surface is 9.5in. The rollers have a horizontal grooving to increase pulling. I will use a hydraulic motor to rotate those rollers. The rotation will be accomplished by using spur gears. The gears will be mounted on each roller shaft to mesh together, while the motor will be mounted directly on one of the rollers shaft. My question is, how I can calculate the torque, power, and rpm required by the hydraulic motor to rotate those rollers if we assume that the force required to pull one plant from the soil is about 5lbs. Thanks!