Hydraulic torque impulse generator

Hydraulic torque impulse generator, comprising:

• a motor-rotated drive member (16) including a hydraulic fluid chamber (18) of a generally cylindrical shape;
• an output spindle (21) having an impulse receiving rear portion (20) extending into said fluid chamber (18) through an opening (42) in the forward end wall (38) of said fluid chamber (18);
• seal means (23, 32, 27, 31) associated with said drive member (16) and said impulse receiving portion (20) of said output spindle (21) and arranged to divide said fluid chamber (18) into at least one high pressure compartment (28) and at least one low pressure compartment (29) during a limited portion of a relative rotation between said drive member (16) and said output spindle (21), thereby producing transient torque impulse generating pressure peaks in said at least one high pressure compartment (28);
• and
• a seal barrier between said output spindle (21) and said drive member (16) for sealing off said fluid chamber (18) from the atmosphere;
• said seal barrier comprising:
• a substantially nonresilient clearance seal means (43) defined by said output spindle (21) and said fluid chamber end wall (38) for preventing said transient pressure peaks from propagating outside said fluid chamber (18);
• a low pressure area (49;
• 61, 62, 67) defined outside of said fluid chamber (18) and communicating with said fluid chamber (18) through said clearance seal means (43);
• and
• a yieldable partition means (46, 64) partly defining said low pressure area (49;
• 61, 62, 67) and communicating on one side thereof with said low pressure area (49;
• 61, 62, 67) and on the other side thereof with the atmosphere, said partition means (46, 64) being arranged to produce volume charges of said low pressure area (49;
• 61, 62, 67) in relation to occurring volume changes in the hydraulic fluid during operation of the hydraulic torque impulse generator.