Power tool comprising a hydraulic pulse unit

A pulse tool comprising:

• a motor;
• an output shaft;
• and
• a hydraulic pulse unit which is coupled to said motor, and arranged to intermittently transfer torque pulses to said output shaft,
• wherein said hydraulic pulse unit comprises an inertia drive member connected to said motor,
• wherein said inertia drive member comprises a hydraulic fluid chamber,
• wherein an impulse receiving portion of said output shaft extends coaxially into said hydraulic fluid chamber, said impulse receiving portion being intermittently coupled to said drive member via a hydraulic pressure pulse generating mechanism dividing said hydraulic fluid chamber into at least one low pressure chamber and at least one high pressure chamber,
• wherein a by-pass passage is provided to communicate fluid between the high pressure chamber and the low pressure chamber, and
• wherein said hydraulic pressure pulse generating mechanism further comprises:
• a first check valve arranged to allow a first flow of hydraulic fluid from said low pressure chamber to said high pressure chamber, and
• a second check valve arranged to allow a second flow of hydraulic fluid from said low pressure chamber to said high pressure chamber.