How Toggle Action Works
Toggle action clamps operate through a linkage system of levers and
pivots. The fixed-length levers, connected by pivot pins, supply the
action and clamping force.Toggle action has an over-center lock point
which is a fixed stop and linkage. Once in the over-center position, the
clamp cannot move or unlock unless the linkage is moved.All types of
toggle clamps have this same action, just oriented differently.
Toggle Action Force Factors
The maximum clamping or exerting force developed in any toggle
action clamp is attained when the three pivot points of the mechanism
are in a straight line. While this is theoretically true, it makes no
allowance for vibration and intermittent load conditions found in
industrial applications. Such conditions would soon unlock an
improperly designed clamp.The proper amount of over-center travel to
produce maximum holding force and yet ensure positive locking is a
carefully calculated and controlled dimension developed by years of
experimentation and experience.
Throughout this catalog each clamp is rated with its “holding capacity.”
This is the maximum load or force the clamp will sustain in the closed
and locked position without permanent deflection. Exerting forces
applied as the clamp closes are less than the holding capacity, and are
dependentonvariablessuchasthepositionoftheoperator’shandonthe
handle; amount of force applied; and position of the spindle on the bar.
ToggleAction Clamps ComparedWith CamAction Clamps
Cam action uses frictional force to effect a locking condition between
the cam surface on the bar and the follower on the handle. Toggle
action clamps have many advantages over cam action clamps, mainly
because cam action clamps allow some movement while clamping.
Toggle action clamps thus provide a more consistent clamping point,