Disk with engagement system for surface cleaning machine

1. A disk with an engagement system for a surface cleaning machine comprising:

a disk having an upper surface, a lower surface and a perimetric edge, the disk having a retaining cavity defined therein;

an engaging member having a base and a perimetric wall, the engaging member being configured to be nested in the retaining cavity and to entrain an inner wall of the retaining cavity;

a first metallic member housed within the disk; and

a second metallic member housed within the engaging member,

wherein the first and the second metallic members are magnetically attracted to one another, and

wherein the first and the second magnetic members are selected to have a magnetic attraction that is larger than a gravity force of the disk and smaller than a predetermined detaching force.

2. The disk of claim 1 , wherein the retaining cavity in the disk is defined by a multi-faceted retaining wall extending upwardly from the upper surface of the disk, and the perimetric wall of the engaging member is a multi-faceted side wall shaped to nest within the retaining wall.

3. The disk of claim 2 , wherein the multi-faceted side wall of the engaging member is inwardly inclined in relation to the multi-faceted retaining wall, thereby facilitating nesting of the engaging member within the cavity and reducing vibration during rotation about a longitudinal axis.

4. The disk of claim 1 , further comprising outer ribs disposed outside of the retaining wall and supporting the retaining wall.

5. The disk of claim 1 , further comprising inner ribs disposed within the engaging member and supporting the perimetric wall.

6. The disk of claim 1 , wherein the first metallic member is housed within a first cavity defined in the upper surface of the disk and the second metallic member is housed in a second cavity defined in an upper side of the base of the engaging member, the first and the second magnets being longitudinally aligned when the engaging member is nested within the retaining cavity and spaced from one another by a residual thickness of the base of the engaging member.

7. The disk of claim 1 , wherein the first and respectively the second metallic members are engaged in the first and the second cavity with a fastener, by adhesive binding, or by interference fit.

8. The disk of claim 1 , wherein the engaging member comprises a plurality of protrusions extending from a lower side of the base, and wherein the disk has a plurality of openings sized and positioned to receive the plurality of protrusions.

9. The disk of claim 8 , wherein the protrusions have a downwardly narrowing frusto-conical shape, thereby facilitating insertion into the openings and reducing vibrations.

10. The disk of claim 1 , wherein the disk has a plurality of through-openings defined therein that drain a fluid lodged on the upper surface of the disk.

11. The disk of claim 1 , wherein the perimetric edge of the disk has a raised perimetric lip that contains a fluid lodged in the upper surface of the disk.

12. The disk of claim 1 , wherein a plurality of slots are defined in the base of the engaging member, the plurality of slots being configured to receive attachment screws of a drive assembly of the surface cleaning machine.

13. The disk of claim 12 , wherein a plurality of slots are defined in the disk, the plurality of slots being configured to receive attachment screws of a drive assembly of the surface cleaning machine.

14. The disk of claim 12 , wherein the plurality of slots comprise larger slots and smaller slots, the larger and smaller slots being arranged in different patterns for receiving attachment screws of different drive assemblies.