Rockmore International’s 5-in.-range ROK 500DH DTH hammer, the newest entry in its Deep Hole series, is intended to drill 5.5 to 6-in. (140 to 152-mm) diameter holes and designed to increase drilling effectiveness and efficiency in deep hole applications that may exceed 1,000 ft (300 m) in depth and include high volumes of water. The hammer has been designed to handle such challenges by incorporating new airflow and component design advancements, primarily in the air ports of the wear sleeve and piston. The ROK 500DH is rated for use with large compressors (24.1 bar / 350 psi at 25.2 m3/min / 890 scfm); however, it can accept greater air volumes and pressures from larger air compressor packages. The upper and lower hammer air chambers of the 500DH have been modified to achieve optimum drilling efficiency. The advanced piston design also offers maximum blow energy with each stroke to the bit, allowing for superior hammer and bit penetration rates in all drilling conditions.
A new bit shank was developed in conjunction with the hammer’s new bit-retention system, eliminating the need for bit retaining rings present in conventional hammer designs. The bit is retained in the driver sub by lobes located on the bit shoulder. If the bit breaks from the shank body during drilling operations, the bit head can be retracted from the hole, retained by the lobes on the bit and driver sub, thus eliminating downtime. Because foot-valve breakages on DTH bit shanks during drilling operations are catastrophic in deep hole drilling—the hammer will cease to function immediately after such a failure—the traditional foot valve, or blow tube component, also has been eliminated in the DH500 shank concept.
An innovative design reduces the number of hammer components, thus reducing the amount of component wear points, making hammer service simpler and less expensive. Lead threads on the top sub and driver sub ensure easy coupling and uncoupling of the hammer. www.rockmore-intl.com