Boart Longyear recently released its new XRH family of rotary heads, comprising 12 base models with various motor configurations, designed for multipurpose rotary drilling applications including jet grouting and reverse circulation. Featuring patent-pending electronic valve control technology, the XRH rotary heads can run two or three motors and seamlessly switch from series to parallel operation, eliminating low-torque startups after making and breaking joints and manual shifting of gears.
The company states the XRH rotary heads are extremely powerful, capable of delivering up to 27,000 Nm (19,915 ft-lb) of torque or a maximum rotation speed of 188 rpm, and engineered to safely handle up to 20,000 kg (44,090 lb) of pullback force. The heads feature hollow spindles with an inner diameter of 120 mm, which is claimed to be the largest in its class and well-suited for passing large jet grouting rods, RC drilling or double-head drilling where a drifter passes a large inner string through the XRH rotary head. The XRH heads also use high-strength axial bearings designed to handle the increased stress experienced by drilling with higher power and speed. An auto oiler supplies constant lubrication to bearings independent of rotary head rotation, extending maintenance intervals and eliminating the need for daily maintenance. Premium bearings, precision ground gears and synthetic seals are also used to provide longer and more reliable head life.