Reduction of hand-arm transmitted vibration on pneumatic jackleg rock drills

CIM Bulletin, Vol. 94, No. 1047, 2001

K. Prajapati, Boart Longyear Inc., North Bay, Ontario P. Hes, Boart Longyear SECO, Roodepoort, South Africa

Transmission of vibration to the operator from percussive vibrating tools is increasingly of concern in industrial and mining applications. Prolonged exposure to high levels of vibration transmitted via the hand causes disorders known as hand-arm vibration syndrome (HAVS). The vascular component of HAVS is called vibration white finger (VWF) and has a debilitating effect on the hand. Vibration at frequencies below 1250 Hz, a tight hand-grip force and cold environments are reported to increase the likelihood of developing VWF. A vibration damping handle design with patents pending that addresses some of the causes of VWF has been developed and retrofits onto jackleg pneumatic rock drills. The handle is decoupled from the drill while maintaining jackleg twist-grip controls on the hand-grip using a combination of sealed self adjusting hydraulic pistons and compliant materials in series, and a new air control valve. The ergonomics of the hand-grip was also modified by the addition of a polyurethane sleeve with a diameter of 50 mm. The new hand-grip reduces direct cold metal contact and minimizes gri
Keywords: Vibration, Hand-arm vibration syndrome (HAVS), Vibration white finger (VWF), Vibrating tools.