Why a soft and adjustable fixing system?

• The soft fixing system consists of rail clips with hot vulcanize-bonded elastomer noses securing the rail which is mounted on a steel reinforced vulcanized rubber pad.
• The system allows the clips, without fatigue, to cope with the stresses in the rail due to the wheel loads and allows controlled free movement of the rail in the longitudinal direction as needed to prevent binding.
• The use of adjustable clips improves the ease of mounting the rail according to required tolerances, and allows for further adjustment that may be needed throughout the track’s life.
• The adjustable clip is the best way to guarantee exact lateral fixing of the rail because it allows for the ability to adjust the rails if required to compensate for deviations from mill rolling and installation tolerances.
• The “soft mounting system” is now the well-known solution that guarantees long term track stability under severe operating conditions.

Weldable or boltable clips?

The decision to use weldable or boltable clips should be based on local site conditions such as accessibility to the underside of the girder, site safety for installation personnel, existing bolt holes, etc.

• A weldable clip, with removable fixing bolt inserted and removed from above, is much easier to install and dismantle than a boltable clip which requires access from both the top and beneath the rail support girder or soleplate.
• Regarding safety, because it is more dangerous when working in high places, installing boltable clips requires movement of the installer and access to both the head of the bolt as well as to the nut.
• Some standards penalize a weldable type solution, by imposing flange thicknesses much more significant than those required for boltable clips. Some national practices forbid welding clips on girder aisles.
• Boltable clips can be supplied as 100% protected by hot dip galvanization : a major advantage against corrosive atmospheres.

What are the common tolerances for rail tracks ?

• Common tolerances for rail installations are more strick as compared to general building or rail rolling tolerances.  The horizontal level and vertical straightness of the individual rail heads, as well as the track span all need to be considered.  They are tighter tolerances than those usually encountered for civil engineering works.
• For these reasons it is important that the rail or track installation be carried out by trained and experienced specialists.
• Detailed information can be found in the related technical standards:
• ISO 12488-1
• FEM 1.001 recommendation
• VDI 3576 recommendation
• ISO 8306 norm
• BS 466 App F
• AIST Technical Report #6
• AIST Technical Report #13
• CMAA Specification #70
• National or local norms and standards

Why and how to weld rails ?

• Welded joints are recommended to avoid shock and vibration when crane wheels pass over the rail joints. This also eliminates the need for punching of holes on the rail ends and the need for splice plates.
• Because the soft mounting system allows for controlled longitudinal movements, stresses due to thermal expansion are eliminated, allowing for long rail or track lengths.
• Rail splice joints do not give a sufficiently tight and stiff link between rail ends.  Some overhead crane rails, such as DIN 536 rails cannot be joined with mechanical splices because of the shape of their profiles.
• The butt welding of rails works best with the soft mounting system.  GANTREX has the experience of continuously welded rail lengths in excess of 1000 m or 3,200 feet.
• Various welding methods are described in the pages titled “Rail Welding” on this site.

How to select rail according to circumstances? Profile? Quality?

• The rail selection depends on factors such as the mounting type :

• for a discontinuous mounting, a high vertical inertia is necessary and leads to the choice of a “high profile” rail.
• for a continuous mounting, either low or high profile rail can be selected.  Note: in a channel, a low profile rail requires a shallower but wider channel.

• The head width must be chosen for each application to match the wheel load and tread width, taking into account applicable standards and rules such as DIN 15070 and FEM 1.001. The rail head width must cope with the crane wheel width, including a play, or float of 5 to 20 mm, according to generally accepted crane design principals .
• Most common European steel grades for rails are 70 and 90 (tensile strength equal to 690 and 880 N/mm² respectively). Higher tensile steels are also available on request.  North American Crane Rail is currently manufactured in Control Cooled, Head Hardened or High Carbon grades.
• Standard European rail length is 12 m. Lengths of 15 and 18 m, are also available, and reduce the number of welds needed. North American Crane Rails are usually standard at 39′ and 78′, with 60′ lengths also available.
• Preference is given to the most frequently rolled profiles, but GANTREX can also provide you with the less common profiles and, when necessary, suggest alternatives.

Is electrical grounding of rails a requirement in any codes or standards ?

• There are currently no codes or standards that address or require the grounding of crane rails. Some owners have welded copper jumper wires across bolted rail splices to provide electrical continuity. Since the splice bars are steel, we feel that this is unnecessary. It is up to the project engineer to determine if grounding of the rail system for lightning protection or cathodic protection in marine environments is needed.

Will the electrical systems on my crane be affected by rail pad ?

• When the crane controls and/or the crane power supply depend on the wheels to make electrical contact with the crane rail, steps must be taken to insure adequate grounding. Grounding of the crane wheels assumes that there is continuity from the wheel/rail interface through the girders and building columns to ground. Many factors can disrupt this grounding path including rubber crane rail pad. Crane rail pad does act as an electrical insulator of low voltage power sources. Although it is true that Gantrex rail clips should theoretically supply a rail to girder grounding path, the clips should not be considered an integral component of the ground path circuit. When the crane electrical system depends on the crane rail for grounding, a grounding strap should be attached from the rail to the girder. This strap should be long enough to account for any longitudinal movement of the rail that may occur. On runways where splice bars are installed a grounding strap at each rail section may be required.

Gantrex rail pad shall never be used an an intentional electrical insulation material.

What corrosion protection alternatives are available?

The choice for the adequate corrosion protection depends on the project. There is no minimum protection obligation for components, as corrosion will depend on many factors beyond our scope. Gantrex can apply most of the usual solutions on the components of the fixing system such as galvanization or special painted systems before or after installation.
Sometimes, even choosing for no protection at all may be best, referring to the cost or practicability, since rail and clip upper components can be easily replaced. It is good practice to choose corrosion protection for embedded parts of the fixing system that may be difficult or expensive to replace. All rail systems should be inspected in compliance with local codes and standards.  Gantrex can help by advising you about inspection criteria, and is available to provide rail and track system inspections.