Case CX 75C-SR RR

Sersa Schweiz has impressed from the first stage of renovation with the use of a new type of 8-tonne crawler excavator with rack-and-pinion operation.

The demands were high: in addition to the mechanical requirements such as excavator equipment and lockable holders for equipment parts, the new crawler excavator of Sersa Schweiz should be able to be quickly converted to track gauges of 800/1000 and 1435mm and should also be able to be used on rack-and-pinion tracks with the Abt and Strub/Riggenbach/Von Roll systems – which can have a maximum gradient of up to 250%. This was made even more difficult by the need to cover the difference in height between the upper edge of the track and the theoretical contact point of the traction units’ pinion with the teeth of the slats, which vary from installation to installation. The originally planned deadline was therefore extended by a full two years. Finally, the new Case CX 75C-SR RR crawler excavator was delivered in October 2019. And it has already proved its worth in the Monte Generoso renovation project.

The excavator is compact and makes optimum progress on the steep ramps of the rack railway without the need for exceptionally high drive power. Its performance also impressed the excavator operators, who feel safe in the driver's cab. The traction drives have a hydrostatic transmission and are both braked. ‘Bellshaped’ wheels ensure that changing gauge is simple and therefore adjusting to the required track width is rapid. Exchanging the cogwheels (racks), which also requires a height adjustment, is somewhat more complex. An innovative construction and conversion procedure was developed specifically for this purpose. The pinions of the wheels and the rack, although vertically on the same level, are divided into three parts, allowing the central part to position the corresponding axle at a different height. Thanks to the possibility of installing an intermediate system without rack and pinion, the crawler excavator can also be used on sections with adhesion drive with a maximum gradient of 70%.