Wiper device for stripping drilling fluid from rig drill string

Abstract From the Canadian patent

The wiper device comprises an elongated conveyor arm which can pivot in a horizontal plane and freely move forward and backward through a limited travel (which movement capabilities are collectively termed "floating" capability). The arm carries a wiper pad assembly on its outer end. The wiper pad assembly can therefore float with the arm to accommodate lateral and to and fro sway of the drill string within the confines of the rig rotary table bushing when the wiper pads are engaged with the drill string. The arm can be advanced and withdrawn to convey the wiper pad assembly between the operative stripping position over the bushing and a retracted position off to one side of the bushing.