High tension in a small box
Tensioning systems from the market leader – “Made in Germany" for more than 60 years
From our wide range of different tensioning systems for chains and belts, we are able to provide a solution for practically any application – quickly and precisely. We will be happy to develop individual solutions for you for machine and plant engineering, such as chain tensioners for dynamic applications or special versions with escapement mechanism.
Our tensioning systems are free-floating and thus have a spring-back effect They therefore do not act as a rigid deflector under load. Excessive surface pressure is thus avoided. The goal is to keep the total force resulting from chain weight and centrifugal force under control in the slack strand. The optimum installation position is close behind the drive sprocket in order to keep the length of the slack strand to be tensioned as short as possible.
The sturdy design of the steel housing makes our tensioning systems very resistant to high mechanical loads. Housings and tensioning systems are galvanised and thus protected against corrosion. A plastic lacquer makes the surface impact and scratch resistant. We also offer a stainless steel range to meet even the highest demands on corrosion resistance. All slide profiles are made from the original "S"® material from Murtfeldt Plastics. Special retention systems initially hold back the spring action. If the retainers are released again after installation, the tensioning pressure is selectively released.
With all Murtfeldt tensioning systems you can choose the tensioning pressure in the two different versions, “light” or “heavy”. Depending on the type, the tensioners are equipped with one, two or three springs. You decide how many springs are to be used. The optimum pressure is thus transmitted to the chain or belt running over the profile.
A major challenge in industrially used chain drives is the gradual increase in sag in the chain due to wear. This standard sag in the slack strand of roller chains in the empty run is approx. 1%. If the elongation exceeds 3%, the chain has to be replaced.
Roller chains constantly become longer due to running-in and wear phenomena. The effects of elongation due to wear are erratic running, sagging in the slack strand and rapidly increasing chain wear. The consequences of the wear are increasing noise and vibrations that can cause the chain to jump and even break.
A chain tensioner compensates the chain sag in the slack strand. The significant reduction in vibration enables smooth running and lowers noise. Wear on the chain joints is reduced and hence the service life of the chain increased. Chain slide rails and return elements complete the optimum operating condition. The goal is to keep the total force resulting from chain weight and centrifugal force under control in the slack strand.
Chain tensioning systems operate only in the slack strand of the chain. The optimum installation position is close behind the drive sprocket in order to keep the length of the slack strand to be tensioned as short as possible. The slide profile of the tensioning system should rest on the chain as perpendicularly as possible in order to create the largest possible contact surface. The maximum permissible chain speed is 1 m/s. The permissible temperature range is -40°C to +60°C ambient temperature. Special solutions are necessary for higher temperature ranges.
Our solution can also be used under dynamic operating conditions, such as reversing mode. When the drive direction is reversed, load and slack strands are also reversed. In this special situation, two Spann-Box® tensioning systems are used. For optimum guidance and increased robustness, we also recommend the use of a return profile.
Murtfeldt’s design engineers will be happy to advise you and, on request, design the turner tailored to your ideas.
We will advise you
Our tensioning systems are particularly gentle on the chain thanks to the free-floating spring principle. By contrast with rigid tensioning systems, this prevents excessive surface pressure. The tensioning force can be optimally set with up to three freely selectable springs. Each spring can be released separately.
We offer a wide range of versions for optimum use in your applications:
The radius of the arc segment profile corresponds to a tooth root diameter of 180 mm and is thus roughly twice that of a normal chain tensioner sprocket.
The semi-circular profile is ideal for use where installation space is at a premium.
The 180° return profile offers the largest possible arc of contact for the chain and is ideal e.g. for use in reversing operations.
The block profile offers perfect guidance for the slide profile in the Spann-Box® housing thanks to the monolithic design of tensioner core and slide profile. The solution ensures maximum robustness even with high dynamic forces.
An adaptation to your individual ambient conditions is possible at any time. Heat-resistant high- performance materials from our portfolio can be used for high-temperature applications. Operation is thus possible at temperatures of more than 150°C.
Materials with high chemical resistance can also be used. In addition to highly resistant plastic slide profiles, our stainless steel metal housings can also be installed. Our tensioning boxes withstand even corrosive conditions.
Our standard products can also be designed as individual solutions for your special requirements.
For example, the Omega tensioning box assembly that offers twice the tensioning distance thanks to the double deflection. This solution is ideal for long chain strands with large sag.
More dynamic response
to changes in chain movement
Reduction of wear
at the chain joints
for chain elongation
and condition monitoring
The right chain tensioner for every challenge – Demonstrated on the example of a lifting table with Spann-Boy® TS-EP
The Spann-Boy® TS-EP is specially designed for use in chain drives with changing operating conditions, or for applications with dynamically changing angles of the chain drive, to be more precise. This becomes clear in the example of the lifting table application shown here. As the platform is raised or lowered, not only the height but also the angle of the slide profile relative to the chain strand changes. This permits optimum support and guidance for the chain on the slide profile, and that in any operating position.
The Spann-Boy® TS-EP is ideal for use with highly dynamic chain drives, in control and positioning applications and with varying distances between centres.
Our experience shows that questions often arise in specific subject areas, such as the installation of a chain tensioner. To answer these questions as well as possible and to provide you with excellent quality advice, we need your technical data. That is why we have drawn up a design questionnaire that lists the information needed.
Please download the questionnaire and fill it in as comprehensively as possible, then send it to us by e-mail. That will enable us to make the right choice without further telephone enquiries and we can give you an answer as quickly as possible.
Please note: To view the file, you will need a PDF reader such as Adobe® Acrobat® Reader, which is free of charge.
We will only process the personal data you have given us to perform the design work that you have commissioned. To this end, we will store the data you have entered and forward it internally to the relevant members of our staff. As a matter of principle, we will not disclose your data to third parties.
You can find more information on our company’s data protection policies in our data protection declaration.