Specifications

Snap Action Switches
Snap Action Switches use a design that enables them to combine a small number of basic
parts to satisfy a wide variety of requirements for selector and control switching of power
circuits. Standard switches built with this design for15-, 40-, 60-, and200-ampere capacities
are listed in this catalog. However, the cataloged units merely indicate switching possibilities; we
will gladly recommend other combinations, based on our experience, for specific requirements.
The Electrical System
The electrical system of the 101 Series
Switch comprises two or more stationary contacts (9)
and one or more sets of movable contacts. These are pairs of spring-metal
blades (8) that make high-pressure, low-resistance contact on both faces of the stationary
contacts while bridging two or more of these contacts. The stationary contacts fit in radial
grooves (12) in the rim of molded insulating disks (7), within which the movable contacts are
carried on an insulated shaft (11). All “making” and “breaking” of electric circuits takes place
within the closed spaces between adjacent disks. Their quick-break action makes these switch-
es particularly suitable for direct-current service. The ends of the stationary contacts extend out-
side the insulating disks and serve as connecting terminals (10 ). This one-piece contact/ter-
minal construction minimizes series resistance and heating. Depending on current rating and
on-wiring requirements, the terminals may have tapped holes for connecting screws or clear-
ance holes for bolt connection of cable-lugs.
The Mechanical System
The mechanical system of the 101 Series Switch is designed to provide uniform high-speed
“make” and “break”, regardless of whether the operating handle (1) is turned rapidly or
slowly. Turning the handle through approximately120˚ in either direction winds a powerful
coil spring (3). When this is fully wound, the indexing plate (4) is momentarily withdrawn
from the locking plate (5) by an eccentric cam. The drive-shaft and movable contacts then
snap rapidly to the next position. The indexing plate holds them until the spring-drive mechanism
is again operated. Transit time is about ten milliseconds.
Assembly
The snap-drive mechanism, mechanism-cover (2), locking plate, mounting bracket (6),
insulating disks, and back plate (14) are stacked on side securing rods (13) and bolted
firmly together to form a rigid assembly. The handle is keyed to the operating shaft and
secured by a screw.
Stationary Contacts
Non-shorting (break-before-make) contacts are standard
in all the ratings and circuits shown in this catalog.
Shorting (make-before-break) contacts, required
in some special circuits, are available on order.
The “sweep” contact maintains the connection with
the rotor through consecutive positions.
Moveable Contacts (Rotors)
The simple, straight-across rotor bridges stationary contacts in the same insulating disk.
It provides single-throw switching in Circuit 1 and double-throw switching in Circuit 6.
The right-angle-blade rotor provides a double-throw switching, with an intermediate
OFF position, in Circuit 7.
A multi-fingered blade is combined with a single-contact blade to form a composite
(double-deck) rotor that interconnects stationary contacts in adjacent disks. Suitable
blade arrangements provide double-throw, triple-throw, or four-throw switching.
Insulating Disks (and Circuits)
The insulating disks, molded of phenolic per MIL-M-14, have three functions. They hold the
stationary contacts, they form enclosures that contain all making and breaking contacts, and
they provide both mechanical and electrical separation of switching sections.
Electroswitch • 180 King Avenue • Weymouth, MA 02188 • TEL: [phone] • FAX: [phone] • www.electroswitch.com
CONSTRUCTION DETAILS
SERIES 101 SNAP-ACTION SWITCHES
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