Germany: Schwenk Zement KG has recently brought into operation two new Liebherr R 980 SME crawler excavators at its limestone quarry in Heidenheim an der Brenz. The quarry is adjacent to Schwenk Zement's cement plant.

The SME crawler excavators from Liebherr are particularly suitable for deployment in excavation and are tailored to the tough operating conditions associated with quarrying. SME stands for 'Super Mass Excavation.' A bonus feature is that the excavator is equipped with a reinforced undercarriage, on which the running gear components of the next larger model from the standard programme, namely the R 9100 mining excavator, can be installed. In conjunction with a heavy ballast weight, this undercarriage improves the stability of the machine and, at the same time, enables the use of a backhoe with greater capacity. The equipment, such as the stick and backhoe cylinders, has been adapted to the higher tearing and breaking out forces with a larger diameter and matching kinematics.

At Schwenk Zement KG, the Liebherr R 980 SME crawler excavators are deployed together with a wheel loader directly at the quarry wall. Material is always excavated using two of the three machines. While the wheel loader is more flexible and mobile, the crawler excavator is suitable for sorting the stone and, at the same time, offers higher tearing and breaking out forces. "We used to work with three wheel loaders in production. With the two Liebherr crawler excavators, we have now found the ideal solution as we have a greater output and productivity and maintain flexibility thanks to the wheel loader," said Wolfgang Kuhnt, Quarry Manager. Since the two crawler excavators have been in operation, the number of detonations for stone excavation has dropped. The bed and material can be collected and processed in a dryer state and the loss of raw material at Schwenk Zement KG can be reduced.

The Liebherr crawler excavators achieve an average material handling performance of 350t/hr and ensure optimum supply of the crushing plant, which is restricted to a capacity of 700t/hr. "The crawler excavators are capable of dealing with 500t/hr as well, however, which equates to 1000t/hr when two are in operation," said Kuhnt. Material transport is then carried out by rigid frame dump trucks with a payload of 65t.