Trench cutting implement has rotating drums with fixed teeth and moving teeth on support actuated by radial pistons and cam surfaces

摘要

The implement consists of a frame (3) with a vertical core (4) and two coaxial hubs (5) carrying rotary drums (6) with fixed (8) and moving (9) teeth which can occupy an inactive position close to the core and an active position away from it. The moving teeth are actuated by spring-loaded pistons (12) sliding radially in apertures (13) in the drum walls (14) and by cam surfaces on the core.