Impact energy and frequency
The impact piston transfers energy through the drill string to the rock. Percussion frequency is the number of piston impacts on the shank adapter per unit of time, commonly expressed in Hz. The guide notes that different rock conditions call for different combinations of impact energy and frequency.
Compare the application and the parameters together rather than choosing on a single number.
Rotation and feed
Rotation torque and drill-rod speed describe rotation performance; feed holds the drill string against the rock. They work together with percussion during drilling.
Before comparing values, confirm the units, measurement conditions and exact model. The condition of a used machine also needs its own inspection.
Information for selection
Share the hole diameter and depth, ground conditions, rig and existing rock drill model, and whether you need a machine or parts. If the model is known, include its complete suffix and a nameplate photograph.
Source: GLOBMACH Hydraulic Rock Drill Parts Selection Guide, printed pages 61 and 78.