UD391 is a compact and flexible single-boom development drill for drilling in narrow vein and mass mining as well as in tunnelling,in cross section up to 34m. UD391 is equipped with Sandvik rock drill and CBI drill control system, which delivers 18kw percussion power for stable and fast drill performancel and long service life for rock tools. The universal LG-B26NV boom is fitted with 360'feed rotation,automatic parallelism large and optimally shaped coverage, for fast and accurate face drilling ande versatility. Direct control drilling hydraulic system featured with automatic control functions ensures the operator to focus on safe,fast and accurated drilling progress.UD391 is mounted on a 4wheel drive frame steered carrier,which features a safety canopy designed according to FOPS standard. The overall layout is designed for good visibility and stability in trammingin small mining drifts and tunnels. The development drill is easy to operate and maintain,and all daily maintenance could be done on ground level.