Sleeper replacement machine

As the main supplier of system solution, our company was responsible for a complex transformation of a special railway utility vehicle designed mainly for railway tracks maintenance. When co-operating with the manufacturer, a local engineering company, our responsibilities included designing and supplying electronic control system of the vehicle as well as travel and work hydraulics.

Sleeper replacement machine SVP 74.1 is an innovated version of the original machine SVP 74. The aim to enhance the machine’s characteristics eventually resulted in a complete renovation of the vehicle. The only features of the former machine that remained unchanged were the chassis (although it was slightly modified) and the axle mount with springing. Design of the wheelset with axle gearboxes has been reinvented. The hydraulic system is run by a 73kW engine which is connected to three hydraulic pumps that power the drive and working unit. The overall concept of the vehicle stayed the same, while the cabin design and bonnet are newly built.  Depending on the requirements, the utility vehicle can be used for replacing the sleepers, but it is expected to be operated mostly for clearing tracks of vegetation and removing snow from railway platforms using a rotary brush.

The machine features a new working unit with air-conditioned cabin, new electrical wiring and improved hydraulic system for travel and work functions. Smooth and accurate control of the vehicle is enabled by two proportional joysticks with integrated switches for selection of drive mode, travel direction and other auxiliary functions. Being connected to the microcontroller, the joysticks can be used either for controlling the travel or the hydraulic arm, but there is also an option of parallel control functions that can be defined by individual settings of the operator. There is space for an extra passenger behind the driver’s seat.

Working hydraulics uses well-proven combination of Danfoss Power Solutions components, specifically the proportional PVG 32 valves and Series 45 axial piston pump, connected to a pair of JS1-H series joysticks. In order to provide a smooth and comfortable control of the work functions, the commands are managed by the MC050 microcontroller. The controller is also responsible for regulating the speed of the combustion engine and adjusting the turn angle and discharge of hydraulic arms to the restricted area when operating on a double-track railway.

The travel is powered by a closed hydraulic circuit which consists of a Series H1P pump and an SVP fixed hydraulic motor which is connected to a two-stage gearbox. The hydraulic pump is controlled by its own electronic unit H1P-AC which communicates with the microcontroller and display via CAN bus. This system is able to produce enough power to generate maximum speed of 60 kmph, which is administratively limited to 40 kmph for the travel mode. For the working mode, the travel speed can be set within the range of 100 meters per hour to 20 kmph. The hydrostatic transmission powers the rear axle.

Operator of the machine is provided with a constant overview of all essential performance data thanks to a 4″ full color display DM430E, which is connected through CAN bus to both of the controllers and a set of sensors.

Another part of the vehicle that has been modernized is the turn power unit, which is now run by a RR310 planetary gearbox paired with an OMR series hydraulic motor, negative break and a break valve that can automatically release the negative hydraulic break.

Jakub Kejduš

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