Reducing sleeve, modular system for providing a reducing sleeve assembly, and machining assembly

A modular reducing sleeve assembly, comprising:

• a reducing sleeve comprising a reducing sleeve body extending along a reducing sleeve center axis, the reducing sleeve body having a first end, which is a tool-side end in the clamped state of the reducing sleeve, and a second end opposite to the first end and is a tool holder-side end in the clamped state of the reducing sleeve, the reducing sleeve body comprising at least one coolant supply channel extending at a distance from the reducing sleeve center axis, the reducing sleeve body further comprising a central coolant supply channel;
• and
• a safety unit mounted on the second end of the reducing sleeve, the safety unit having a pull-out safety geometry and a plurality of coolant holes in fluid communication with the at least one coolant supply channel of the reducing sleeve,
• wherein coolant is directed to a machining tool only through a central coolant supply channel of the safety unit when a sealing element is mounted on the safety unit, and
• wherein coolant is directed through the plurality of coolant holes of the safety unit and the at least one coolant supply channel of the reducing sleeve when the sealing element is not mounted on the safety unit.