The DIN 25193 standard specifies a T-bolt with a D-shaped head. The head's cross-section features a distinctive flat on one side. This design allows the bolt to be inserted laterally into a matching D-shaped T-slot (or T-slot with a keyway) and then rotated 90 degrees. Upon rotation, the flat side of the head locks against a corresponding flat surface inside the slot, providing positive anti-rotation in the axial direction. This makes it a crucial fastener for heavy-duty and high-vibration applications.

Specifically engineered for heavy loads, it is commonly used in rail transportation (e.g., bogies, major component connections), heavy-duty machine tools, large stamping presses, injection molding machines, and mining machinery. These applications demand exceptional resistance to vibration and loosening.

Common Materials:

• High-Strength Alloy Steel: Grades like 40Cr or 42CrMo, heat-treated (quenched and tempered) to achieve high property classes such as 8.8, 10.9, or 12.9. This is the primary choice for maximum load-bearing capacity.
• Stainless Steel: For corrosion-prone environments (e.g., food processing, chemical, or outdoor equipment), A2-70 (304) or A4-80 (316) stainless steel is used.

1. Positive Anti-Rotation: The mating of the D-shaped head and slot provides a mechanical lock, preventing the bolt from rotating and loosening under severe vibration, ensuring supreme safety and reliability.
2. High Load Capacity: The large contact area between the head and the slot allows for even load distribution, enabling the bolt to withstand extremely high shear forces and preloads.
3. Convenient Installation: The bolt can be inserted laterally into the slot at any point, not just from the end, and then rotated to lock. This is particularly advantageous for the maintenance of large equipment.
4. Repeatable, Precise Positioning: The D-shape ensures the bolt is always oriented the same way within the slot, facilitating accurate repositioning of jigs and fixtures.