Sandvik DL421 long-hole drills can be equipped with a longer (horseshoe) boom support for up to ±45° drilling module tilt in drilling fans or single long-holes. The maximum tilt angle backwards can be achieved by keeping the support in horizontal position; it is equipped with hydraulic jacks so it can sufficiently be stabilized for acceptable drilling stability. When the boom support is kept on the ground the boom tilt angle in the extreme back position is 30° from vertical.
In addition to feed extension, units with longer boom support are equipped with a telescopic feed cradle that allows the greater boom tilt angles.
The wider boom tilt range increases the versatility of the DL421 in down-hole drilling or if holes need to be drilled parallel to the contact of the orebody. This feature is also suited for drop raise and drainage hole drilling. Units equipped with this feature have the same boom coverage and drilling module rotation, compared to standard units.