Donut Cribbing

Donut Cribbing

Donut cribbing is a new, patented concept in roof support that gives you many advantages over traditional cribbing. Their consistent quality gives you support you can rely on. Your miners will like them because they're easy to handle, require far less piece per crib and you need less cribs per entry. You'll like the savings in labor costs.

Disc cribbing offers over 40% more bearing area than donuts and is designed for areas of extremely high loading.

The Loan Transfer Discs (LTD) are 1/8" thick fiber shims inserted between every 3 or 4 courses as the stack is built. The LTDs assure equal distribution of load throughout the crib.

Donut Cribbing

Better Than Block Because ...

  • Donuts give 14% more bearing surface on every crib, and it's continuous - not just on four corners.
    They require far less back-breaking effort to install.
    There's 40% less pieces to handle - 40% less weight to transport and stack.
  • Base preparation is much easier. You only need to set one piece reasonably level.
  • Donuts cause less air turbulence, less resistance improves ventilation flow.
  • Donuts flat surfaces eliminate point loading, common in block cribbing which leads to early and rapid failure.
    Donuts are easier to handle. They can even be rolled into place in low coal.
Donut Cribbing

MAG Donut Cribbing is also available

  • Donuts give you consistent quality through rigid production control.
  • Donuts don't shrink away from the roof or new rewedging.
  • Donuts provide substantial early support to reduce sagging or heaving.
  • They keep your roof strata tight - won't compress excessively.
  • Donuts keep their strength - can't rot or burn.
  • Their smooth, round shape reduces air turbulence - improves ventilation flow.
  • Donuts reduce your labor costs because fewer cribs are needed.

Testing shows mode of failure is gradual. The Mag-Donut Crib has load bearing capacities up to 1,000,000 pounds.

The mechanical stacking of Mag-Donut Cribs increases the production of a five man cribbing crew from 15 timber cribs per 10 hour shift to over 50 Mag-Donut Cribs utilizing a 3 man crew.