Fishbolts for Rail S-49

Fishbolts for S-49 (also known as 49E1) rails are specialized heavy-duty fasteners used to secure fishplates (joint bars) to the ends of two rail sections. These bolts are typically manufactured according to DIN 5903 or UIC 864-2 standards to match the 30mm bolt hole diameter of the S-49 rail profile. 

Standard Specifications

Dimensions: For S-49 rails, fishbolts typically feature diameters ranging from M20 to M24, with lengths determined by the combined thickness of the rail web and the fishplates.

Bolt Grades: Common mechanical property grades include 8.8 (high tensile) and 10.9, though mild steel grades like 4.6 or 5.6 are also used for lighter applications.

Materials: Usually forged from carbon steel (e.g., Q235, 35#, or 45# steel) or alloy steel (40Cr).

Surface Treatment: Options include plain (oiled), oxide black, zinc-plated, or hot-dip galvanized (HDG) for corrosion resistance. 

Exact Dimensions

For S-49 (also known as 49E1) rails, the exact dimensional drawings for fishbolts typically follow the DIN 5903-1 standard for round-head bolts with oval necks (BHON). Because S-49 rails have a standard bolt hole diameter of 30mm, they generally utilize M22 or M24 bolt sizes.

DIN 5903-1 Dimensional Parameters (mm) 

The following table provides the technical dimensions for the standard M22 and M24 fishbolts commonly used with S-49 rail profiles:

Key Technical Notes

Oval Neck Purpose: The neck is designed to fit into the oval-shaped holes of the S-49 fishplate. This locking mechanism prevents the bolt from spinning while the nut is being tightened.

Nut & Washer: These bolts are typically paired with high-strength hexagonal nuts and heavy-duty spring washers to maintain tension under high traffic loads.

Grade Requirements: Grade 8.8 or 10.9

Application Details

Assembly: A standard joint for S-49 rails typically requires four or six fishbolts paired with matching nuts and spring washers to prevent loosening under traffic vibrations.

Head Design: They often feature a cup head with an oval neck (BHON) or a square head to prevent the bolt from turning while being torqued from the nut side.

Compatibility: These bolts are essential for both permanent track laying and temporary repairs using Joggled Fish Plates.