No percussion
The guide lists possible causes including hydraulic pressure problems, uneven or bent tie bolts, and scoring of the piston or distribution valve. Each needs separate inspection; absence of percussion alone does not establish that the piston must be replaced.
Record the operating conditions, pressure information, warnings and recent service history for a technician familiar with the model.
Rotation binding and component damage
The guide illustrates several forms of rotation trouble, including a sticking sequence valve, damaged rotation sleeve and damaged gears. It also describes a case where uneven mounting-bolt torque led to binding.
Its discussion of impact-piston face damage includes salt and fluid corrosion. Keep photographs and consider the environment and condition of the part; a case example does not prove the cause in another machine.
Inspection and parts matching
Follow the equipment manufacturer's procedures and safety requirements for inspection and repair. For parts, provide the model, version, part number, damage location and photographs, then confirm compatibility before ordering.
Source: GLOBMACH Hydraulic Rock Drill Parts Selection Guide, printed pages 88, 98 and 108.