Adjustable electropneumatic hammer drill - incorporates system to vary stroke of piston which actuates hammer head

摘要

The electro-pneumatic hammer drill has a piston (26) which is actuated by a connecting rod (23) and a crankshaft (12). The crankshaft (12) has a crankpin (19') which is formed integrally with a block (19) which fits in a diametral slot (18) formed in the end face of a boss (17) which forms part of the crankshaft. The crankshaft (12) has an axial bore (22) which receives an inner shaft (21) which has an end part (21') which is inclined at an angle (alpha) to the main part and engages an oblique hole (20) in the block (19). The inner shaft (21) can be locked in either of two axial positions by means of a ball catch (29) so that the end part (21') is moved further into or out of the oblique hole (20) in the block (19) to provide two different radial positions of the crankpin (19') and so vary the stroke of the piston (25). USE - Hammer drills.