Bolt preloading check system

A bolt system for indicating a level of preload of a bolt that is connectable to a subject to be fixed, the bolt system comprising:

• the bolt which comprises a bolt head;
• a first sleeve attached to the bolt between the bolt head and the subject;
• and
• a second sleeve attached to the bolt between the bolt head and the subject,
• wherein the first sleeve is an inner sleeve and the second sleeve is an outer sleeve that fits around the first sleeve,
• wherein one sleeve is longer than the other sleeve,
• when the preload is below a maximum value the longer sleeve transmits the preload between the bolt head and the subject, and
• when the preload is above the maximum value, the longer sleeve is compressed in such a way that both sleeves transmit the preload between the bolt head and the subject.

A method of indicating a level of preload of a bolt that is connectable to a subject to be fixed, the method comprising:

• attaching a first sleeve and a second sleeve to the bolt between a bolt head and the subject, wherein the first sleeve is an inner sleeve and the second sleeve is an outer sleeve that fits around the first sleeve and wherein one sleeve is longer than the other sleeve;
• transmitting the preload between the bolt head and the subject by the longer sleeve when the preload is below a maximum value;
• and
• compressing the longer sleeve when the preload is above the maximum value in such a way that both sleeves transmit the preload between the bolt head and the subject.