3 Common Rail Fastening Components for Crane Rails

Crane rails and their fastening system

A crane rail is a heavy steel rail used to support and guide cranes in industrial environments. It can be mounted on the ground or on elevated structures such as runway girders in workshops, ports and stockyards. Rigid rail cranes are mainly used in heavy industry, including automobile manufacturing, shipbuilding and assembly plants, where large goods must be transported across the workshop. The rail runway gives the crane a precise, repeatable path, and the fastening system keeps the rail fixed to that path under every load condition.

Crane rail profiles in the QU series

Rail type	Height (mm)	Bottom width (mm)	Head width (mm)	Web depth (mm)	Theoretical weight (kg/m)
QU70	120	120	70	28	52.8
QU80	130	130	80	32	63.69
QU100	150	150	100	38	88.96
QU120	170	170	120	44	118.1

The fastening components must match the base width of the selected profile: a QU100 runway and a QU120 runway use different clamps and baseplates. The three component groups that make up the crane rail fastening system are rail clamps, fishplates (joint bars) and rail pads.

1. Rail clamps

Rail clamps are the primary fastening that holds the crane rail down on its support, whether a concrete foundation, a steel girder or a sleeper bed. They are fitted on both sides of the rail foot at regular intervals and tightened with bolts. Rail clamps are self-locking and adjustable, and they provide a high clamping force that prevents the rail from moving laterally and longitudinally while allowing controlled thermal movement of the rail along its length.

Correct clamp spacing and torque are essential: too loose, and the rail creeps under crane travel; too tight, and thermal expansion has nowhere to go, buckling the rail. The clamp base is matched to the rail base width and the support type.

2. Fishplates (rail joint bars)

Fishplates, also called joint bars, connect two sections of crane rail at the joints. The plate is bolted to the rail web on both sides of the joint with fish bolts, so that the two rail ends act as one continuous rail for the crane wheel. The joint bar prevents breakage and misalignment of the rail at the joint, where the wheel impact is highest.

Joint alignment is critical on crane runways: a dipped or raised joint hammers the crane wheels and spreads the runway girder. Fishplates for crane rails are made in matching lengths and hole patterns for each rail section, and can be supplied in insulated form where electrical sectioning of the runway is required.

3. Rail pads

Rail pads are placed between the rail and the supporting structure to reduce vibration and impact and to protect the support. A crane rail pad is typically made of rubber or a resilient compound so that it cushions the wheel load, protects the baseplate and the support from abrasion and impact, and prolongs the service life of the clamps and the rail seat. On elevated runways the pad also damps the vibration transmitted into the building structure, which is important for crane runways above working areas.

How the three components work together

The three component groups are designed as a system. The rail pad sits on the support, the rail foot bears on the pad, the clamps hold the rail foot down on both sides, and the fishplates tie the rail ends together at the joints. Together they keep the rail in gauge and alignment, transmit the wheel load to the support, cushion the impact and allow controlled thermal movement. A runway that is missing or has worn any one of these components will show it quickly in rail movement, joint hammering and fastener loosening.

Frequently Asked Questions

Why are rail clamps used instead of rail spikes on crane rails?

Crane rails sit on steel girders or concrete supports where hammered spikes cannot grip. Clamps bolt around the rail foot and provide a high, adjustable clamping force matched to the runway design, and they allow the rail to be repositioned and re-tightened during maintenance.

How often should crane rail fastenings be inspected?

Fastenings should be checked on a regular schedule based on crane duty, with torque verification on the clamps and inspection of joint bars and bolts. Heavy-duty runways are typically inspected at shorter intervals than light-duty lines.

What happens if the rail pad wears out?

A worn pad removes the cushion between rail and support, so the clamp bolts work loose, the rail seat is damaged by impact, and vibration increases. Worn pads are replaced during fastening maintenance.

Do crane rail joints need fishplates on both sides of the rail?

Yes. Standard practice is two fishplates, one on each side of the rail web, bolted through the web. This balances the bending moment across the joint in both directions.

Can the same fastening be used for ground-mounted and elevated crane rails?

The same component types are used, but the baseplates and clamps are designed for the support: concrete foundations, sleepers or steel girders each need a different clamping arrangement and fixing detail.

What rail fastening is needed for the QU120 profile?

QU120 has a 170 mm base width, so the clamps and baseplates must be sized for that base and for the higher wheel load. All components, including the pad width and fishplate length, are selected to match the QU120 section.