Double expansion anchors for medium to heavy duty in concrete, block, brick and stone.

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Concrete Double Expansion Anchor

Double Expansion Anchors

The double expansion anchor works well in soft masonry and mediums of questionable strength. As the "double" sets, the two opposing wedges pull towards each other, expanding the full length of the anchor body. Eliminates high stress points detrimental in fastening into materials of medium hardness, has high gripping power and expands fully.

Commonly Called

Purchase Double Expansion Anchors OnlineDouble expansion shield, keystone double, double thunderloc, double, DMSA, machine screw anchor.

Double Expansion Anchor Features

  • Can be used in concrete, brick, block or stone.
  • Use with machine screw bolt or screw.
  • Dual expansion develops greater contact with walls of hole.
  • Ideal for sheer loads or where bolt is subjected to side pressure or vibration.
  • Proper expansion requires that anchor, prior to setting, protrudes slightly above surface plane.

Double Expansion Anchor Description

The double expansion anchor consists of a nut, a cone and a tubular shield preassembled as a single unit. The two-piece tubular shield is bound together with two spring bands. It contains a wedge shaped nut at one end and a wedge shaped hollow cone at the other end. Integral lugs on the nut and cone keep the wedges from turning in the tubular shield during expansion. The anchors are of precision die-cast zinc alloy commonly known as Zamak 5. The expansion action at both ends of the shield distributes the anchored load throughout the length of the shield. This expansion anchor is recommended for shear loads or where the bolt is subjected to side pressure or vibration. Once fastened, the object may be unbolted, removed, and/or fastened.

Double Expansion Anchor Approvals

Meets Zamak 5 Zinc Alloy: A.S.T.M. Specification 24 (AC41A) and S.A.E. 925.

Applications for Double Expansion Anchors

Purchase Double Expansion Anchors OnlineMedium to heavy duty in concrete, block, brick and stone.

Anchor Spacing considerations for Double Expansion Anchors

The forces on a Double expansion anchor are transferred to the material that it is installed in. If the anchors are installed too close together, it can cause an interaction of the forces, thus reducing the holding power of the anchor. As a rule of thumb, the expansion industry has established a minimum standard of ten (10) anchor diameters for spacing between anchors and five (5) anchor diameters from an unsupported edge. When vibration or sudden impact is part of the load condition anchor spacing should be increased.

Deciding Length of bolt needed for Double Expansion Anchors

Thickness of material to be fastened plus length of anchor equals bolt length.