chain as in fig1 or they may have separate side chains side chains 24 are attached to harrow 14 may be attached directly or via front spreader bar 18 so the rear bolt attachement to the second row of digging knife units 12 pulls harrow 14 front spreader bar 18 and rear spreader bar 20 are attached to harrow 14 and chains 16 chains 16 are patterned to form a reinforcement for harrow 14 that dramatically reduces the damage sustained from a mine detonation if harrow 14 is not covered with a chain blanket it is lifted and torn apart by the blast it was found that the unexpected protection provided by chains 16 occurs because the extra reinforcement they provide is sufficient to prevent harrow 14 from being lifted by the explosion consequently most of the energy and momentum from the mine explosion escapes before it can spread through the harrow 39 s loose lattice like structure and only local damage is sustained this may be easily repaired because harrow 14 has a modular construction of 1 m u00d7 2 m sections of course chain blanket 16 is not required for farming in a preferred embodiment all chain sections are 3 8 34 high test schedule 70 and are 16 39 long side chains.