Mechanical pencil with a side button and an eraser dispenser and a method of assembly

1. A mechanical pencil comprising: a barrel extending in a longitudinal direction, a lead-propelling mechanism, a lead reservoir, a side button, and an eraser-propelling mechanism having a helical cam, the lead-propelling mechanism, the lead reservoir, the eraser-propelling mechanism, and the side button being at least partly housed inside the barrel, the lead-propelling mechanism, the lead reservoir, and the eraser-propelling mechanism being prevented from rotating about the longitudinal direction relative to one another and relative to the side button, and the side button is prevented from rotating about the longitudinal direction relative to the barrel, wherein rotation about the longitudinal direction is prevented by a system including a plurality of ribs, each rib including a beveled longitudinal end.

2. A mechanical pencil according to claim 1 , wherein the lead-propelling mechanism is prevented from rotating about the longitudinal direction relative to the lead reservoir and the lead reservoir is prevented from rotating about the longitudinal direction relative to the eraser-propelling mechanism.

3. A mechanical pencil according to claim 1 , wherein the lead-propelling mechanism is prevented from rotating about the longitudinal direction relative to the side button.

4. A mechanical pencil according to claim 1 , wherein the barrel includes a slot extending in the longitudinal direction and the side button comprises an actuator portion and an annular ring, connected together by a stem, the side button being prevented from rotating about the longitudinal direction by cooperation between the stem and the slot.

5. A mechanical pencil according to claim 4 , wherein the annular ring has an outside surface that is substantially spherical.

6. A mechanical pencil according to claim 1 , wherein the side button includes an annular ring arranged inside the barrel, and wherein the lead-propelling mechanism includes a chuck holder, the chuck holder being prevented from rotating about the longitudinal direction relative to the annular ring.

7. A mechanical pencil according to claim 1 , wherein the lead-propelling mechanism includes a chuck holder, the lead reservoir being prevented from rotating about the longitudinal direction relative to the chuck holder.

8. A mechanical pencil according to claim 1 , wherein the eraser-propelling mechanism includes a guide cylinder prevented from rotating about the longitudinal direction relative to the lead reservoir.

9. A mechanical pencil according to claim 1 , wherein the lead-propelling mechanism, the lead reservoir, and the eraser-propelling mechanism are coupled together longitudinally.

10. A mechanical pencil according to claim 9 , wherein at least one longitudinal coupling is longitudinal snap-fastening.

11. A method of assembling a mechanical pencil comprising the steps of:

providing a barrel extending in a longitudinal direction, a lead-propelling mechanism, a lead reservoir, an eraser-propelling mechanism having a helical cam, and a side button;

preventing the side button from rotating about the longitudinal direction relative to the barrel;

inserting the lead-propelling mechanism into the barrel and preventing the lead-propelling mechanism from rotating about the longitudinal direction relative to the side button by utilizing a system for preventing rotating including a plurality of ribs including beveled longitudinal ends;

assembling the eraser-propelling mechanism and the lead reservoir together and preventing the eraser-propelling mechanism from rotating about the longitudinal direction relative to the lead reservoir; and

inserting the lead reservoir and the eraser-propelling mechanism into the barrel and preventing the lead reservoir from rotating about the longitudinal direction relative to the lead-propelling mechanism.

12. A method according to claim 11 , wherein the side button comprises an actuator portion and an annular ring connected together by a stem presenting an axis, wherein the barrel includes a slot extending in the longitudinal direction, and wherein the annular ring of the side button is inserted into the slot of the barrel and the side button is rotated through 90° about the axis of the stem, the side button being prevented from rotating about the longitudinal direction by cooperation between the stem and the slot.

13. A method according to claim 11 , wherein the lead-propelling mechanism, the lead reservoir, and the eraser-propelling mechanism are coupled together longitudinally.