The successor to the first fully mechanised cable-bolting rig from Sandvik, the well known Cabolt, the all-new DS421 benefits from the legacy of three decades of first-class cable bolters. Sandvik states: “Offering excellent safety, serviceability and efficiency – with a record of 13,000 metres of grouted cable bolts per month – the one man operated DS421 is a true boost for productivity.” The new Sandvik DS421 is designed especially for rock reinforcement in underground mines and tunnels with small and medium cross sections. With a working width of 3.9 m and a working height from 3.2 to 8.4 m, combined with a small turning radius, it is a good match for the 4 x 4 drift size class. As a self-contained unit with an onboard steel strand reel, a cement mixer and c cement bag platform, the DS421 can install cement grouted cable bolts up to 25 m in depth.

Featuring a powerful HL510 drill, it is also an effective backup for production drills. As safety regulations all over the world become stricter, Sandvik Mining says that it aims to actively design safety into its products. To reach this goal, safety has been integrated into product development projects to make sure safety aspects are considered at every step of the design process. The DS421 drill rig design is based on the EN 791 drill rigs’ safety and EN ISO 12100 safety of machinery standards. These standards set requirements for different aspects of product design, such as operator’s position, access systems, stability and braking systems. As normal parts of the design process, risk assessments and other safety analyses and tests have been carried out. With the analyses in place at different stages of the design process, the aim is to verify that the end product is safe. In addition to the international standards EN 791 and EN ISO 12100, the design of the DS421 has also been based on many other standards, guidelines and design philosophies, such as the highly valued Australian guideline MDG 15 for mobile machinery for use in mines and also on Canadian standard CSA M424.2-M90 for diesel powered machinery for use in underground mines. The DS421’s standard features such as front protection bars to protect the operator from loose or flying rocks, two normal access ways with anti-slip surfaces, drilling on electrical power to reduce the risk of diesel particulate matter (DPM) and the use of fire retardant materials all improve operator safety. Comfort and ergonomics are evident in the adjustable seat, easy access to most service points and vibration dampening of the cabin/canopy. The new carrier layout with the potential to conduct daily maintenance from ground level further adds to the high EHS standards of the rig.

One of the main advantages of the DS421 is the possibility to perform the full bolting cycle from start to finish with just one operator. Compared to manual installation, which still is the main method for cable bolting, the DS421 offers outstanding productivity rates from the average of 6,000 to 8,000 m to its record of 13,000 m of grouted cable bolts per month. The mechanised bolting cycle allows installation of several steel strands per hole and the process can be executed in two different ways: drilling all the holes before grouting and installing cable bolts or drilling and bolting holes one by one, the latter alternative being recommended especially in challenging ground conditions. Because to its steel strand bending system ensures the strand stays in the hole during upward installation, no manual wedge installation is needed.