Thanks to their special torsional elasticity, spring couplings from Torsion Control Products (TCP) are ideal for use in mobile machines in road construction where modern diesel engines are used. For a manufacturer of road milling machines, TCP developed a solution with a coil spring coupling that significantly increased the service life of the entire machine.
Removing road surfaces
In road construction, asphalt road surfaces are removed with road milling machines. Removal is carried out with the aid of a rotating milling drum fitted with cutting tools. The advantage of milling is the targeted and precise removal of pavement layers and a fast construction process. Road milling machines can be used for a wide range of applications, from complete removal of pavement layers to levelling asphalt and concrete surfaces. Today, mainly cold milling technology is used, in which the milling tools are very hard and the road surface does not need to be heated up. Modern cold milling machines can load a 30-tonne truck with asphalt granulate within a few minutes.
Clutch failures, unexpected shutdowns, significant traffic disruptions: these were some of the problems a leading manufacturer of road construction equipment and blacktop pavers faced with two of its road milling machines. The configuration of the milling machine included a diesel engine with a flange-mounted torsionally flexible elastomer coupling from another coupling manufacturer, a shift coupling, a gearbox and the milling drum. The torsionally flexible coupling is intended to positively influence the torsional vibrations in such a way that the other components in the driveline are protected from damaging resonance vibrations.
In addition, this coupling in a road milling machine must be able to absorb high impact torques that can occur during operation from the output side. However, the elastomer coupling used could not meet these requirements. The customer required an operating time of at least 3000 hours between two service intervals - but the elastomer coupling failed after only 200 to 1000 hours of operation. The premature and unexpected failure of the elastomer coupling caused high costs due to the downtime of the road milling machine. Additional equipment had to be hired to dismantle the machine and terminate the job in order to replace the coupling. As a result, the downtime led to significant traffic disruptions and problems in the field.
Increased service life, saved costs
To determine the necessary characteristics of the coupling, TCP engineers undertook a torsional vibration analysis of the application. Within six weeks, TCP delivered a new coil spring coupling designed specifically for this application. TCP also carried out on-site tests to determine whether the coupling met the expectations of the torsional vibration analysis in the application. The analysis included the gearbox, the flexible coupling and the hydraulic clutch. In the end, the coil spring coupling was able to increase the service life of the entire machine. The operating time tripled to more than 3000 hours without malfunctions. The conversion enabled the road milling machine manufacturer to achieve significant cost savings.
Torsionally elastic spring couplings
Thanks to their special torsional characteristics, spring couplings from TCP are particularly suitable for modern diesel engines that achieve low emission values, have a high power density and deliver high torques at low speeds. Even under the harshest operating conditions, they dampen driveline vibrations and ensure reliable operation. With the help of the "Smart Damping" system, the spring clutches are adjustable and can be optimally matched to the respective drive system. Depending on the situation, torsional vibrations are damped or the vibration systems are decoupled if damping would have an unfavourable effect on the overall system. Torque peaks during start-up, shut-down and short, fluctuating events are reduced, which in turn significantly increases the service life of the coupling.