sprag

Mine roof prop

A sprag is a wooden prop or strut used to prevent movement—especially a piece of timber braced against a mine roof or a chock wedged behind a wheel to keep a vehicle from rolling.

In mechanical contexts, a sprag clutch uses angled pawls that jam to prevent rotation in one direction while allowing it in the other.

The verb means to prop or block with such a device.

ratchet

pawl

Hinged mechanical stopper

  • detentMechanism holding position temporarily
  • catchSeize or snag
  • backstopBarrier behind target area

freewheel · escapement · click · tooth · engagement · torque · rotation · winch · mechanism

prop

chock

Stabilizing wedge

  • blockSolid mass, or impede
  • wedgeTapered splitting tool
  • shimThin piece for leveling

scotch · brake · stopper · restraint · immobilizer · anchor · holdfast · spacer · buffer · stabilizer

mining

coal

Combustible sedimentary rock

  • tunnelEnclosed underground route
  • shaftNarrow vertical passage
  • gallerySpace for displaying artwork

timbering · shoring · underground · miner · colliery · adit · drift · stope · tram · ventilation

Opposites
motion control function

spragpropeller

Rotating blades creating thrust

motor · engine · accelerator · throttle · pusher

mechanical action

spragrelease mechanism

Device that unlocks restraint

freewheel · release

Family

sprags

Familiarity
Top 1,000,000
Profile
Used worldwide · Timeless · Concrete · Rated G