Classification of Cams and Followers

There is not a general classification for cam mechanical systems. However, the 'functional embodiments' and 'functions' of each sub-system have relatively few possibilities, which we can classify.

Note:

There is often confusion with the term cam-follower, in English at least. The term Cam-follower is often used for both the element that is in direct contact with the cam and the element that has its motion defined by the cam.

Where possible, I will use the term Cam-Follower for the part that has its motion defined by the cam.

There are two common shapes of the element that are in direct contact with he Cam - circular and flat. I will use the term Cam-Roller Follower when it is rolling bearing, and Flat-Faced Follower when it is a Flat-Face. For other shapes, it should be clear. from the context.

A General Classification of Cam and Cam-Follower Types:

tog_minusCam Shape

The general shape of the cam is generated by the interaction of the cam and follower motions.

Planar:

The cam is a disc, plate, track, groove, conjugate, ramp, slot

Spatial:

Spatial: the cam is cylindrical, barrel, globoidal,

tog_minusCam Motion

The modes of cam motion are:

Rotating Cams:

The cam swings back and forth: ; the cam 'oscillates'
The cam rotates continuously

Translating Cams:

The slide back and forth; the cam 'reciprocates'

Stationary Cams:

The cam is a plate that is nominally 'Circular', fixed to a frame (most common on rotating machinery - such as bottle labelling, capping and filling machines).
The cam is a ramp that is nominally 'Linear', for example it is a 'slot' or 'ramp'.

tog_minusCam-Follower Shapes

The shape of the follower influences the shape of the cam.

Cylindrical Roller Follower
Taper Roller Follower - use with barrel, globoidal and other non-planar cams.
Barrel (also called a Crowned) Roller Follower.
Logarithmic Roller Follower - the actual function is the intellectual property of each manufacturer.
Knife-edged Follower - not a practical cam-profile shape, but included here for completeness
Flat-faced Follower
Other 'general' shapes.

See Typical Cam-Profile Shapes

tog_minusCam-Follower Motion

The modes of cam-follower motion are:

Rotating Followers: a lever:

Swing back and forth:  an oscillating follower
Progressive motion, they index, in one direction

Translating Followers: a slider:

Sliding back and forth: a reciprocating follower

Stationary Followers:

The Stationary Cam-Follower moves the Cam, not as common, molding machines, wedge
A stationary follower might be used to position a cam part, like a 'wedge' cam.

tog_minusConstraint between Cam and Follower

The constraint between the cam and the follower shape influences whether the cam is 'open' or 'closed'.

Force Closed:

The constraint between cam-follower and the cam is with:

Gravity, Spring, Air-Cylinder, ...

Form Closed (also called Body Closed):

The constraint between the cam-follower and the cam is with a:

Groove (Track), Rib, Slot, within which the cam-follower is constrained.
Conjugate Cams: these systems require manufacturing and production accuracy for a follower to be in contact with each cam.

tog_minusType of Motion

Non-progressive:

The follower returns to the same position after each cycle by reversing its direction of motion at some point in the cycle.

Progressive: (also called 'indexing', see also Indexing Cams) )

The follower moves progressively to a new position at the end of each cycle.

In most cases the follower is replaced by another follower at the end of a motion cycle. Equally spaced followers return to their original positions after a number of motion-cycle. Most indexing systems use several roller followers equally spaced around a follower wheel or 'turret'.

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