VBK duoblok fastening
An improved rail clamp for duoblok sleepers that restores a constant clamping force regardless of wear in the socket, sleeper or bedding plate, extending track life by 10 to 15 years.
The first duoblok sleepers in the 1980s used the so-called Nefit spring; later all were converted to the SKL-75 clamp, fixed with a special bolt. After more than twenty years in service the SKL clamp loses clamping force and rails risk coming loose, mainly because the cast-in sockets wear: the fixing bolt tilts back and the clamp is pressed in less far.
KamPa developed the VBK in response. The clamp uses an insulator that gives the clamp an extra support point to rest on, so tightening the bolt readily delivers the required clamping force regardless of the condition of the socket, sleeper or bedding plate. Alongside higher clamping force, the VBK also improves the rail's insulation resistance on duoblok sleepers.
The problem it solves
A declining SKL clamp lets the rail work loose.
On duoblok track the rail is held by the SKL-75 clamp and a special bolt seated in the cast-in sockets. As the sockets wear, the bolt tilts back and the clamp is pressed in less far, so the clamping force drops below what the rail needs.
Once the clamping force is insufficient, the wear accelerates: the sockets degrade further, the bedding plate under the rail thins, and the clamping force falls further still. In curves this leads to gauge widening and damage to the duoblok sleepers, ultimately forcing track renewal.
Benefits
The clamp holder is loaded vertically only.
The extra support point removes the point-loading on the clamp holder. It now carries the load vertically instead of being worked sideways, so the fastening and the sleeper last longer.
Adjustable and re-adjustable clamping force.
Tightening the bolt sets the required clamping force regardless of the condition of the socket, sleeper or bedding plate, and it can be re-adjusted later as components wear.
The spring clip cannot run back or rotate out.
The VBK holds the spring clip in place: it cannot run back or rotate out of position over time, so the rail stays fastened between maintenance visits.
15 years more life from existing track.
Applying the VBK to duoblok track extends its service life by 10 to 15 years, deferring renewal of the sleepers and the superstructure around them.
In the field
Documentation & links
Manuals, brochures and where to order.
Request more information about VBK duoblok fastening.
Datasheets, installation manuals and reference projects. An engineer replies within one working day.
Or call +31 (0)162-70 05 20
Thank you, your request has been sent.
An engineer will get back to you within one working day.