Grade 5.6 to UIC864-1 24x161mm DHS35 Screw Spike

Dog spikes and screw spikes are the two most common rail spikes in track fastening. A screw spike works by the thread on its shank: it is screwed into the sleeper or an embedded dowel and holds with far higher pull-out resistance than a hammered spike, which is what keeps the fastening secure under repeated train loads. The DHS35 screw spike is one such fastener, specified as 24×161 mm to UIC 864-1 in property class 5.6.

What grade 5.6 means

Property class 5.6 per ISO 898-1 guarantees a minimum tensile strength of 500 MPa and a yield strength of 300 MPa (the ratio 0.6 of 500 MPa). The DHS35 is therefore a medium-strength fastener: stronger than the common 4.6 class but still formable and ductile enough for thread rolling and galvanizing. This class is widely chosen for export fastening systems because it balances strength, cost and processing behaviour.

24×161 mm DHS35 to UIC 864-1

The 24 mm diameter and 161 mm length suit the standard concrete sleeper fastening systems specified under UIC 864-1, where the screw engages an embedded plastic dowel and holds the rail clip or base plate in position.

Ss series screw spikes to UIC 864-1

ASTM A66-87 screw spikes for the US market

For US track projects, sleeper screw spikes are supplied to ASTM A66-87 with a cold bending requirement of 90 degrees without cracks. Standard strength is 65000 psi, with a high-strength option at 100000 psi. Common sizes are 3/4 in, 7/8 in and 15/16 in. The cold bend test verifies that the steel is ductile enough to survive installation and service bending without fracture.

Screw spikes with big disk for Africa and South America

Rail screw spikes with a big disk under the head are applied mainly in South America and Africa, where softwood sleepers and rebound conditions require a larger bearing area under the head so the fastener does not pull through the sleeper surface. Available sizes are 22 mm and 23 mm diameter, with lengths of 115 mm, 133 mm and 178 mm. The disk spreads the clamping force and improves the holding behaviour in softer sleeper materials.

FAQ

What is the difference between DHS35 and Ss35?

The DHS designation refers to the double-head screw spike family, while Ss35 is a type in the Ss series to UIC 864-1. Both serve similar fastening duties; the exact drawing of the head form and thread defines which one your fastening system needs.

Why is the 90 degree cold bending test specified for US spikes?

ASTM A66-87 requires the spike to withstand a 90 degree cold bend without cracks to guarantee ductility. A brittle spike would snap during installation or under service bending loads, so the test is a quality gate on the steel heat treatment.

When should I choose the 100000 psi high-strength spike?

Choose the high-strength option when the fastening system demands higher holding force or when the sleeper material is hard and requires a stronger thread. For general freight track, the 65000 psi standard strength is the economical default.

What is the big disk for?

The big disk increases the bearing area under the head so the spike does not sink into or pull through soft sleeper surfaces, which is a common failure on softwood and composite sleepers in Africa and South America.

Does UIC 864-1 cover the torque for installation?

UIC 864-1 defines the spike requirements; the installation torque is given by the fastening system specification. For 24 mm class spikes in plastic dowels, typical values are in the range of 100-200 Nm.

Can DHS35 spikes be used on timber sleepers?

Yes, with a pre-drilled pilot hole. The thread grips the timber and gives better pull-out resistance than a dog spike, provided the timber is sound and the pilot hole matches the drawing.