Cam Pitch Radius
Calculate the pitch radius of a roller-follower cam, R_p = R_b + R_r, from the base circle radius R_b (mm) and the follower roller radius R_r (mm). In ROLLER-follower cams (a bearing rolling on the cam profile, reducing friction versus flat-face or knife-edge followers), two important curves are distinguished: the real PROFILE of the cam (the physical surface the roller touches) and the PITCH curve, the locus of the roller CENTER as it follows the cam. The pitch curve is designed first (from the displacement diagram), and the real profile is obtained by 'offsetting' the roller radius from the pitch curve. The pitch radius, at the base position, is the sum of the base circle radius and the roller radius. This distinction is fundamental for a practical reason: the roller radius cannot exceed the smallest RADIUS OF CURVATURE of the pitch curve in CONCAVE regions, or the roller does not 'fit' and the cam gets an incorrect profile (undercutting), distorting the motion. So the choice of roller radius and base radius is coupled to the cam geometry. The pitch radius also enters the pressure-angle and peripheral-speed calculations. Enter the base circle radius and the roller radius.
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Raio primitivo do came
O raio primitivo (de passo) de um came de seguidor de rolete é R_p = R_b + R_r, a partir do raio do círculo de base R_b e do raio do rolete do seguidor R_r. Em cames com seguidor de rolete (um rolamento que rola sobre o perfil do came, reduzindo o atrito em relação ao seguidor de face plana ou de ponta), distinguem-se duas curvas importantes: o perfil real do came (a superfície física que o rolete toca) e a curva primitiva (de passo), que é o lugar geométrico do centro do rolete conforme ele segue o came. A curva primitiva é o que se projeta primeiro (a partir do diagrama de deslocamento), e o perfil real é obtido 'descontando' o raio do rolete da curva primitiva. O raio primitivo, na posição de base, é a soma do raio do círculo de base com o raio do rolete. Essa distinção é fundamental por uma razão prática: o raio do rolete não pode ser maior que o menor raio de curvatura da curva primitiva nas regiões côncavas, senão o rolete não 'cabe' e o came fica com perfil incorreto (undercutting), distorcendo o movimento. Por isso a escolha do raio do rolete e do raio de base está acoplada à geometria do came. O raio primitivo também entra no cálculo do ângulo de pressão e da velocidade periférica. Informe o raio do círculo de base e o raio do rolete.
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Cam Pressure Angle
Calculate the pressure angle of a radial translating-follower cam, α = arctan((ds/dθ) ÷ (R_b + s)), from the displacement derivative with respect to angle ds/dθ (mm/rad, the profile 'slope'), the base circle radius R_b (mm) and the follower displacement s (mm). The pressure angle is the angle between the direction of the FORCE the cam applies to the follower (normal to the profile, at the contact point) and the direction of the follower MOTION. It is a critical design parameter: the LARGER the pressure angle, the greater the LATERAL force component (perpendicular to follower motion), which does no useful work but pushes the follower against its guides, causing friction, wear and possibly JAMMING the follower if excessive. The rule of thumb limits the pressure angle to about 30° (less for translating followers with long guides). The pressure angle depends on the profile (ds/dθ, steeper = larger angle), the base radius (larger cams have smaller angles and smoother operation) and the displacement. So when the pressure angle comes out excessive, the solution is to INCREASE the base circle radius (bigger cam) — at the cost of more space, mass and peripheral speed. Controlling the pressure angle is essential for smooth, durable operation. Enter the displacement derivative, the base radius and the displacement.
Circle Area Calculator
Calculate the area of a circle from its radius. Formula: A = π × r². Instant result in the browser.
Max Acceleration (Parabolic Cam)
Calculate the (constant) maximum acceleration of a parabolic-motion (constant-acceleration) cam follower, a_max = (4·h·ω²) ÷ β², from the total lift h (mm), the cam angular velocity ω (rad/s) and the rise angle β (rad). Parabolic, or constant-acceleration, motion is the law producing the LOWEST possible maximum acceleration for a given lift and time — so it minimizes peak inertia forces. It consists of two halves: in the first, the follower accelerates with CONSTANT acceleration (rising parabolic displacement); in the second, it decelerates with the same constant (negative) acceleration, stopping at the top. The name 'parabolic' comes from the displacement diagram, formed by two parabolas. The great advantage is the low maximum acceleration; the drawback is that acceleration JUMPS abruptly — from +a_max to −a_max at the middle, and from zero to ±a_max at the ends — generating infinite JERK there, causing shocks, noise and vibration. So in practice pure parabolic is little used at high speed (despite low peak acceleration), and cycloidal or modified profiles that smooth these transitions are preferred. Parabolic is didactic and useful when peak acceleration is the limiting factor and speeds are moderate. Enter the lift, the angular velocity and the rise angle.
Follower Displacement (SHM)
Calculate the displacement of a simple-harmonic-motion (SHM) cam follower, s = (h/2)·(1 − cos(π·θ/β)), from the total lift h (mm), the cam angle θ (rad, current position) and the rise cam angle β (rad, ramp duration). A cam is a special-profiled mechanical element that, rotating, imposes a programmed motion on a FOLLOWER sliding or pivoting on it — the heart of engine valve trains, automatic machines, textile, printing and packaging equipment. Simple harmonic motion is a classic follower motion law: displacement follows a cosine, starting smoothly from rest, accelerating to mid-height and decelerating smoothly to rest at the top. It has continuous velocity and acceleration (no jumps), but acceleration is discontinuous at the ends (start and finish), causing a small shock — so SHM suits moderate speeds. The follower displacement diagram (s vs θ) is the starting point of cam-profile design: from it derive velocity, acceleration and jerk, which set the forces, vibrations and accuracy of the mechanism. Enter the lift, the current angle and the rise angle.
Mean Friction Radius (Clutch)
Calculate the mean friction radius of a disc clutch or brake by uniform-wear theory, r_m = (D + d) ÷ 4, from the outer D and inner d diameters (m) of the friction annulus. The mean radius is the EFFECTIVE radius at which the resultant friction force is taken to act for torque calculation (T = μ·F·N·r_m). There are two classic assumptions for this radius: UNIFORM WEAR (assuming the disc has 'bedded in' and wears evenly, concentrating pressure at the inner radius; gives r_m = (D+d)/4, the simple mean of radii) and UNIFORM PRESSURE (new disc, constant pressure; gives r_m = (2/3)·(D³−d³)/(D²−d²), slightly larger). Uniform wear is most used in DESIGN, being conservative (slightly lower torque) and representing the run-in steady state. The mean radius shows an interesting design point: discs with a narrow friction annulus (D close to d, thin ring at large radius) have a high mean radius, transmitting more torque per unit force — so high-performance disc brakes use calipers acting near the disc edge (large radius). Enter the outer and inner diameters.
Max Velocity (Cycloidal Cam)
Calculate the maximum velocity of a cycloidal-motion cam follower, v_max = (2·h·ω) ÷ β, from the total lift h (mm), the cam angular velocity ω (rad/s) and the rise angle β (rad). In cycloidal motion, the follower velocity follows a smooth (1 − cosine) curve, starting from zero, reaching the MAXIMUM at mid-rise and returning to zero at the top — similar in shape to SHM, but with a slightly different profile ensuring acceleration continuity. The cycloidal maximum velocity (factor 2) is slightly HIGHER than SHM's (factor π/2 ≈ 1.57), reflecting that, to 'fit' the same lift in the same angle with smoother end accelerations, the mid velocity must be higher. Knowing the maximum velocity matters for the mechanism dynamics (the follower-mass kinetic energy, supplied then absorbed each cycle), for friction and wear at the cam-follower contact, and to check the system can follow the cam at high rpm. Comparing the maximum velocities and accelerations of the three classic laws (parabolic, SHM, cycloidal) is the basis of choosing the right cam profile per combination of load, speed and smoothness requirement. Enter the lift, the angular velocity and the rise angle.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.