How Do Toggle Clamps Work?

A toggle clamp is a versatile workholding product used to hold a stationary workpiece in a locked position. This is especially useful for injection molding, production lines, welding applications, and more.

Toggle clamps are quick-action clamping tools that operate using an over-center locking principle known as a “toggle action.” Utilizing a system of levers and pivots, the clamping handle moves a linkage to its center position and the clamping arm meets the center to hold the fixture or workpiece in a locked position.

Examples of how to use toggle clamps include positioning machine tools or holding molds together, but there are a variety of other workholding applications for your requirements.

Discover more about how toggle clamps work by learning about “toggle-action” principles, holding capacity, clamping force, and the different types of toggle clamps below.

Moving into position

Applying clamping force

Locking over center

A toggle clamp is a quick-acting mechanical linkage where two of the elements make up a toggle action. Actuating the clamp first moves it into position, then applies clamping force by compressing or stretching the linkage elements after contacting the workpiece, then positively locks it by moving the toggle action's center pivot past the centerline of the other two pivots, against a stop.

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The "holding capacity" listed for each toggle clamp refers to the maximum external force that clamp can safely resist in its locked position without incurring any permanent deformation. For hold-down clamps, holding capacity is measured with the spindle as close as possible to the handle, and will be less at the end of the clamping arm.

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Open-arm hold-down clamps offer maximum flexibility and adjustability. Two flanged washers hold the spindle in place anywhere along the arm by tightening the jam nuts.

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