Many railroad components and equipment are named after animals, some because of appearance and others because of a similar principle. Two of the most common railway fasteners in this family are the railway fishplate and the dog spike. Both play essential roles in the track: the fishplate connects rail ends, and the dog spike fixes the rail to the sleeper. Understanding these parts helps buyers specify the right components for their track system.
The Railway Fishplate and Its Name
The rail joint is used to connect the ends of two rails and bond them together. It has another name, the railway fishplate, because the cross section of the early rail joint was made into the shape of a fish tail. Under the action of the fish bolt, the fishplate is pressed tight and the ends of the rails are fastened together. When heavy steel rails appeared, the cross section of rail joints changed, but the name fishplate is still used today.
Fishplate Standards and Mechanical Properties
| Standard | Material | Rail Sizes | Tensile Rm | Elongation |
| UIC 864-4 and UIC 864-8 | 40 steel | UIC54, UIC60 | 550 to 650 MPa | 18 percent or more |
| DIN 5902-1995 | Q235 or Q295 | FL30 to FL49 rails | 375 MPa or more | 21 percent or more |
| TB/T 2345-2008 | 55 steel | 43, 52, 60, 75 kg | 785 MPa or more | 9 percent or more |
| BS 47-1 | 40 steel | BS75R to BS113A | 550 to 650 MPa | 18 percent or more |
The DIN 5902 fishplates have a yield strength of 235 MPa or more, and the TB/T 2345 fishplates have a yield strength of 520 MPa or more with a Brinell hardness of 227 to 388 HBW and a 30 degree cold bend test without cracks. These values ensure the joint bar can transfer longitudinal forces between rail ends.
The Dog Spike and Its Name
The dog spike is one type of railroad spike, used to fix the rail to the railroad tie in the track. In the time of wooden sleepers, the dog spike was the special rail product for fastening steel rails. The dog spike has two lugs on the head that look like a dog head, which is why it is called a dog spike. It has been said that the dog spike guards the steel rails loyally like a dog.
Dog Spike Specifications
| Specification | Material | Surface | Standard |
| 5/8 inch by 6 inch | A3, Q235, 45 steel, 55 steel | According to customer needs | Per drawings or samples |
| 9/16 inch by 5-1/2 inch | A3, Q235, 45 steel, 55 steel | According to customer needs | Per drawings or samples |
| 3/8 inch by 3-1/2 inch | A3, Q235, 45 steel, 55 steel | According to customer needs | Per drawings or samples |
| 1/2 inch by 3-1/2 inch | A3, Q235, 45 steel, 55 steel | According to customer needs | Per drawings or samples |
How Fishplates and Dog Spikes Work Together
The fishplate connects the ends of two rails and transfers forces across the joint, while the dog spike fixes the rail base to the tie plate and sleeper. Fish bolts clamp the fishplate against the rail web, and the dog spikes hold the assembly in gauge. Both components are part of the wider fastening family that also includes rail clips, tie plates, and fish bolts, and all of them keep the rail safe together.
Frequently Asked Questions
Why is the rail joint called a fishplate? The cross section of the early rail joint was shaped like a fish tail, and the name fishplate has remained in use.
What is a dog spike? dog spike is a railroad spike with two lugs on the head that look like a dog head, used to fix the rail to the railroad tie.
Which standards cover railway fishplates? Common standards are UIC 864-4, UIC 864-8, DIN 5902, TB/T 2345, and BS 47-1.
What is the tensile strength of UIC fishplates? UIC 864 fishplates in 40 steel have a tensile strength of 550 to 650 MPa with elongation of 18 percent or more.
What sizes of dog spikes are available? Common sizes include 5/8 by 6 inch, 9/16 by 5-1/2 inch, 3/8 by 3-1/2 inch, and 1/2 by 3-1/2 inch.
