Contact angle - When referring to ball bearings, the contact angle is the angle between the line of action of the ball load and the plane perpendicular to the bearing axis.
Corebox - Pattern makers and foundry people make a distinction between the outer portion and the inner portion of a casting. The “pattern” that defines the outer or external portion of a casting is referred to as a pattern, and the “pattern” that defines its inner portion is referred to as a corebox. Read more.
Cover - the part of the pump that is required to complete the case of a radial split pump.
Critical speed - the rotating speed at which resonance occurs with the natural frequency of a rotor, or rotating assembly. The natural frequency of a rotor is the frequency at which it will develop its highest vibration; it is affected by the stiffness, or spring constant, and the weight, or mass, of the rotor. A pump should not run at, or close to, its critical speed because it will result in excessive and damaging vibration. See dry critical speed, and wet critical speed.
Cutwater - an imaginary circle drawn from the shaft centerline and tangent to the tip of the volute lip/s.
Cutwater diameter - the diameter of a cutwater, or the diameter of a circle tangent to the volute lip/s and whose center is at the shaft centerline. The cutwater diameter is used in calculating the pump's B-gap.