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Series 20 Cam-Action Switches
The design principle allows the combination of a relatively small number of basic parts to sat-
isfy a wide variety of requirements for selector and control switching in power circuits.
The Mechanical Design
The switch features a modular design with switching decks (3) stacked with a detent mecha-
nism deck (6), a mounting plate (12), and a handle (13). A steel shaft (10) couples the
handle to the operating parts. Two steel securing rods (11) are used to bolt the whole mecha-
nism rigidly together. The basic parts and assemblies are shown above.
The Detent Assembly
The detent assembly (6) consists of a spring-loaded detent block (7) with a roller coming
into contact with a notched detent wheel (8). This detent wheel provides the standard 45°
detenting as well as optional 30°, 60°or 90°detenting. The stop arms (9) are located under
the mounting plate. These limit the angular rotation to the desired number and location of
The Contact Assembly
The contact assembly (3) consists of a rigid thermosetting plastic housing, two sets of stationary
contacts (5), and two spring-loaded (16) movable contacts (1) held in cam followers (2).
Floating on the shaft and held within the contacting chamber are two independent cams (4).
The cams are notched to provide the contact close angles desired. The contacts are spring
-loaded closed and mechanically opened by the cam action to avoid sticking. The terminal
screw (15) and pressure clamp (14) will easily accommodate stranded wire with lugs or solid
wire, either with or without lugs, compatible with switch size.
The contacting consists simply of shunting
two isolated contacts to make a circuit.
Two independent sets of contacts are
placed in each deck. The moving portion
is spring-loaded to close the contact. A
notch on the cam is affixed to the operating
shaft allowing the moving contact to spring
close, bridging the stationary contacts.
The movable contact (1) is spring-loaded (16) and held by the cam follower (2). It makes
a circuit with the two stationary contacts (5) when the cam follower enters the notch in the
Identically, the same thing is happening with the contact set on the right. This circuit is held
open by the cam and will close when the notch on the second independent cam is rotated
around and comes in proximity to its cam follower (the second cam notch is illustrated by
the dotted linesthe cam is underneath the other one).
We show the contacts pictorially to agree with typical detailed schematics and wiring plans. This
simple system makes the switch contact arrangement, performance and location independent
of the switching action required. The switching action is varied and controlled by the shape
of the cams allowing a virtually infinite number of combinations using a few standard parts.
This simplicity and flexibility makes it easy for you to design your own switch using familiar
contact language. You eliminate the worry, long deliveries, high costs, etc. normally associated
with special switches.
Note: The terminal numbering consists of individual numbers for each terminal for positive