Patent ID: 8317160

Claim:
An apparatus comprising: a platform; a hoisting machine mounted on the platform; a rigging operable to raise and lower the platform, said rigging passing through a traction sheave mounted on the hoisting machine, said fraction sheave coupled to a restraint device, said restraint device located proximate to where said rigging passes through said traction sheave and positioned substantially at a position of maximum lifting of said rigging, wherein a gap is formed between an outer radius of said rigging and said restraint device such that the outer radius of said rigging is allowed to pass through said traction sheave while to limit lateral displacement of said rigging is limited; wherein said restraint device comprises: at least one removable attachment point for coupling said restraint device to said traction sheave; a first edge operable for limiting said lateral displacement of said rigging; and a second edge opposite to the first edge, wherein the first and second edges approximate a contour of said traction sheave, said restraint device being substantially symmetrical in a major longitudinal axis such that said restraint device can be rotated about said longitudinal axis to present said second edge for limiting said lateral displacement; wherein said first and second edges respectively have an indication of a degree of wear so that a user can flip the restraint device from the first edge to the second edge in order to replace the first edge which is indicating wear.