Sandvik HL820ST is a hydraulic top hammer rock drill designed for DL311 and DL321 underground longhole drills. It is capable of drilling Ø54 - 89 mm holes up to 38 meters in depth, using T35, T38, T45, T51 MF-rods or Ø65 mm tube rods.
Sandvik HL820ST hydraulic rock drill is designed to ensure high drilling capacity, easy maintenance and low operating cost. The construction of the rock drill is based on the main body modules tied together with four short side bolts; this ensures minimum number of joint faces and large contact surfaces. The percussion module is simple in design and consists of only two moving parts – the piston and the distributor sleeve around the piston. The moving parts are not in contact with the rock drill body modules.
The HL820ST is fitted with a drill stabilizer, which is designed to adjust percussion power according to variations in rock conditions. This ensures good rock/bit contact and energy transfer, high penetration rate and rock tool service life.
There are two rotation motor variants to meet the rotation torque and RPM requirements of different hole diameters and rock formations. The optional power extractor is used for opening rock tool joints manually or automatically when using one-hole or fan automation. The design of the HL820ST is covered by several patents.