Radial-Translating Roller Follower

A radial-translating roller follower is a type of cam-follower mechanism commonly used in high-speed applications. It consists of a roller that moves radially along a cam profile, transmitting motion from the cam to the follower.

Statement 1: Parabolic motion of the follower is very suitable for high-speed cams.

Parabolic motion refers to the motion of the follower along a parabolic path. This type of motion is often preferred for high-speed cams due to several reasons:

1. Reduced wear and friction: Parabolic motion allows for smooth and continuous contact between the follower roller and the cam profile, resulting in reduced wear and friction. This is particularly important in high-speed applications, where the contact forces and velocities are relatively high.

2. Improved dynamic performance: Parabolic motion provides better dynamic performance compared to other motion profiles, such as simple harmonic motion or uniform velocity. It helps to minimize impact forces and accelerations, thereby reducing vibrations and increasing the overall system stability.

3. Lower contact stress: The curved profile of the parabolic motion distributes the contact forces more evenly along the follower roller. This results in lower contact stress on the roller and the cam, reducing the risk of failure or damage.

Therefore, statement 1 is correct. Parabolic motion of the follower is indeed very suitable for high-speed cams due to its advantages in terms of wear, friction, dynamic performance, and contact stress.

Statement 2: Pitch point on the pitch circle of a cam corresponds to the point of maximum pressure angle.

The pitch point on the pitch circle of a cam refers to the point of contact between the cam profile and the follower roller when the follower is at its highest position. The pressure angle at a given point on the cam profile is the angle between the normal to the cam profile and the direction of motion of the follower roller at that point.

The pressure angle is an important parameter in cam design as it affects the contact forces, friction, and wear between the cam and the follower. In general, a smaller pressure angle is desirable to reduce the contact forces and wear.

However, the statement that the pitch point corresponds to the point of maximum pressure angle is incorrect. The pitch point is actually the point of minimum pressure angle on the cam profile. At the pitch point, the pressure angle is minimized, resulting in reduced contact forces and wear.

The maximum pressure angle occurs at other points on the cam profile, typically when the follower roller is near its lowest position. These points are often referred to as the dwell or dwell points. The maximum pressure angle is associated with higher contact forces and wear, which can be a concern in cam design.

Therefore, statement 2 is incorrect. The pitch point on the pitch circle of a cam corresponds to the point of minimum pressure angle, not the maximum pressure angle.