Editing Cam (mechanism) (section)

==Cylindrical cam==
[[image:Threading setup helix and bushing American pacemaker lathe.png|thumb|Constant lead barrel cam in an American Pacemaker lathe. This cam is used to provide a repeatable cross slide setting when threading with a single-point tool.]]
A '''cylindrical cam''', or  '''barrel cam''', is a cam in which the follower rides on the surface of a cylinder. In the most common type, the follower rides in a groove cut into the surface of a cylinder. These cams are principally used to convert rotational motion to linear motion perpendicular to the rotational axis of the cylinder. A cylinder may have several grooves cut into the surface and drive several followers. Cylindrical cams can provide motions that involve more than a single rotation of the cylinder and generally provide positive positioning, removing the need for a spring or other provision to keep the follower in contact with the control surface.

Applications include machine tool drives, such as reciprocating saws, and shift control barrels in [[Sequential manual transmission|sequential transmissions]], such as on most modern [[Motorcycle transmission|motorcycles]].

A special case of this cam is a '''constant lead''', where the position of the follower is linear with rotation, as in a lead screw. The purpose and detail of implementation influence whether this application is called a cam or a screw thread, but in some cases, the nomenclature may be ambiguous.

Cylindrical cams may also be used to reference an output to two inputs, where one input is the rotation of the cylinder and the other is the position of the follower along the cam. The output is radial to the cylinder. These were once common for special functions in control systems, such as fire control mechanisms for guns on naval vessels<ref>{{cite book
| author1 = Bomar | author2 = Null | author3 = Wallace
| year = 1996
| title = Gunners Mate 1 & C NAVEDTRA 14110
| pages = 4–2
| publisher = Naval Education and Training Professional Development and Technology Center
| url = https://www.scribd.com/doc/7824710/US-Navy-Course-NAVEDTRA-14110-Gunners-Mate-1-C}}</ref> and mechanical analog computers.<ref>{{cite journal
| last = Clymer | first = A. Ben
| journal = IEEE Annals of the History of Computing
| title = The Mechanical Analog Computers of Hannibal Ford and William Newell
| pages = 19–34
| volume = 15 | issue = 2
| url = https://www.scribd.com/doc/7824710/US-Navy-Course-NAVEDTRA-14110-Gunners-Mate-1-C
 | doi=10.1109/85.207741| year = 1993
| s2cid = 6500043
}}</ref>

An example of a cylindrical cam with two inputs is provided by a [[duplicating lathe]], an example of which is the Klotz axe handle lathe,<ref>{{YouTube|id=dVuel1F5mXo|title=House handles Klotz lathe}}</ref> which cuts an axe handle to a form controlled by a pattern acting as a cam for the lathe mechanism.