Equipment for testing materials for stress corrosion cracking

Apparatus for testing materials for stress corrosion cracking comprising:

• (a) at least two tensioning units, each unit including a base plate (3), two guide columns (2) mounted on said plate, an upper stationary cross-beam (1) mounted on said columns, a lower movable cross-beam (4) vertically slidable on said columns, means for clamping said lower cross-beam to said columns, sample holding means, and means for moving said lower cross-beam, said lower cross-beam comprising a cross plate, four guide nuts (7) and two tubes (5), said guide nuts being mounted on the ends of the tubes which ride on said columns and carry said cross-plate, said clamping means comprising a slotted guide nut (6) operatively associated and carried by one of said tubes, said holding means comprising quick coupling means (9),(10) connected with said upper and lower cross-beams, said cross plate carrying a connecting flange 13 secured to said cross-plate by detachable screws;
• and
• (b) a drive power block mounted on said base plate comprising at least one drive gear (23) operatively associated with said means for moving said lower cross-beam and a motor power unit driving said at least one drive gear, said motor power unit comprising two stepping motors (41,42), a sun gear (43) driven by one stepping motor, an annular crown gear (45) driven by the other stepping motor, at least one planetary gear (44) in driving engagement with said gun gear and said crown gear, an arm (48) carrying said planetary gear and a drive shaft (49) carrying said arm, said drive shaft being operatively associated with said at least one drive gear.