Power wrench

1. A power wrench comprising:

a motor having a motor shaft;

a drive unit connected to said motor and including a gear set driven by said motor shaft;

an output unit connected to said gear set, and including

an output spindle that is driven by said gear set and that is rotatable about a rotation axis transverse to said motor shaft, said output spindle having an axial through hole that extends through said output spindle and that opens at two axially opposite ends of said output spindle, said axial through hole being configured to permit passage of a bolt, and

a first socket member directly connected to said output spindle at one of said two axially opposite ends, said first socket member having a first socket hole aligned with said axial through hole and configured to engage a nut, a screw head, or the like;

a housing unit covering said motor, said drive unit and said output unit, and having two opposite housing openings which open outwards of said power wrench and each of which aligned with said first socket hole and said axial through hole to provide a passage extending through said first socket hole and said axial through hole and between said opposite housing openings;

wherein said drive unit further includes a spring and a flywheel sleeved on said output spindle and urged by said spring to move toward said first socket member, said flywheel being rotatable along with said output spindle and having a plurality of drive projections projecting toward said first socket member; and

wherein said first socket member further has a plurality of radial projections engageable with said drive projections.

2. The power wrench as claimed in claim 1 , wherein said output unit further includes a second socket member opposite to said first socket member and disposed at the other one of said two axially opposite ends of said output spindle, said second socket member having a second socket hole aligned with said first socket hole and said axial through hole and configured to engage a nut, screw head or the like.

3. The power wrench as claimed in claim 2 , wherein said output unit further includes a tubular connection member that connects between said first and second socket members in communication with said first and second socket holes and that is disposed inside said axial through hole.

4. The power wrench as claimed in claim 1 , wherein said output unit further includes a second socket member having an engagement portion removably engaging said first socket hole, and a second socket hole configured to engage a nut, a screw head, or the like, said second socket hole being communicated with said axial through hole.

5. The power wrench as claimed in claim 1 , wherein said gear set has a sun gear mounted to said motor shaft, a carrier, a plurality of planetary gears meshed with said sun gear and mounted to said carrier, a ring gear surrounding and meshed with said planetary gears, a first bevel gear connected to said carrier, and a second bevel gear meshed with said first bevel gear, said ring gear being positioned to said housing unit, said carrier being concomitantly rotatable with said planetary gears, said first bevel gear being concomitantly rotatable with said carrier.

6. The power wrench as claimed in claim 5 , wherein said second bevel gear is hollow and is sleeved on said output spindle for concomitant rotation.

7. The power wrench as claimed in claim 5 , wherein

said spring is connected between said second bevel gear and said flywheel.

8. A power wrench comprising:

a motor having a motor shaft;

a drive unit connected to said motor and including a gear set driven by said motor shaft;

an output unit connected to said gear set, and including

an output spindle that is driven by said gear set and that is rotatable about a rotation axis transverse to said motor shaft, said output spindle having an axial through hole that extends through said output spindle and that opens at two axially opposite ends of said output spindle, said axial through hole being configured to permit passage of a bolt, and

a first socket member connected to said output spindle at one of said two axially opposite ends, said first socket member having a first socket hole aligned with said axial through hole and configured to engage a nut, a screw head, or the like;

a housing unit covering said motor, said drive unit and said output unit, and having two opposite housing openings which open outwards of said power wrench and each of which aligned with said first socket hole and said axial through hole to provide a passage extending through said first socket hole and said axial through hole and between said opposite housing openings;

wherein said drive unit further includes a flywheel that is sleeved on and rotatable along with said output spindle and that is urged by a spring toward said first socket member, said flywheel having a plurality of drive projections projecting toward said first socket member;

wherein said first socket member has a first end portion inserted into said axial through hole, a second end portion disposed distally from said axial through hole, and an intermediate portion disposed between said first and second end portions; and

wherein said first socket member further has a plurality of radial projections which are engageable with said drive projections of said flywheel and which protrude radially from said intermediate portion.

9. The power wrench as claimed in claim 8 , wherein said first socket member further has an annular flange protruding radially from said intermediate portion between said second end portion and said radial projections and having a flange surface facing said radial projections, said radial projections lying on said flange surface.