NKFI tender

With the tender no. GINOP-2.1.7-15-2016-00424 INVENT Engineering Office Ltd. won a tender to design, develop and to produce the prototype of a narrow-gauge running bogie. With the previously developed motorized bogie the modern narrow-gauge bogie family is complete.

What could be the criteria to a modern (universal) narrow-gauge bogie?

• The main criteria for a bogie is its “off-road skill”, to be able to adapt to railway tracks with bad condition. It has to guarantee the proper safety of running whether it is a good or a bad conditioned railway track.
• Another criteria, that connects to the previous one is the design to avoid further damage of the railway track, the two-staged spring assembly.
• Low mass, and within the minimum unsprung mass.
• Low maintenance requirement.
• High passenger comfort even in bad railway tracks.
• Environmentally friendly design, low sound pollution, closed lubricant spaces with improved sealing.
• Make sure that the most parts of the motorized bogie can be used for a running bogie. (universal)

Univerzális futó forgóváz főbb méretei és elemei

• Gauge: 760 mm
• Wheel diameter: 600 mm
• Wheel-base (Axle distance): 1700 mm
• Axle-load: 5-6 t
• Nominal speed: 20-60 km/h

Bogie frame:

A forgóváz keret egy acéllemezekből összehegesztett, – felülnézetben „H” alakú – szekrényes tartószerkezet, amely a forgóváz merev vázát alkotja. A forgóváz kerethez csatlakoznak a kerékpár csapágyházai, a primer és szekunder rugózás elemei, a vonószerkezet és fékszerkezet. Így a forgóváz keret közvetíti a hossz-, kereszt- és függőleges irányú erőket a kerékpárok és kocsiszekrény között.

Wheel-set:

The wheel-set is produced in a traditional way. It is a press-fitted separate tyre. The axle is guided with spherical roller bearings, which can withstand the dynamic effects of the bad conditioned railway tracks. They have long service life and they does not need frequent maintenance. The bearing houses connect to the bogie frame via silent blocks. This design ensures the good “off-road skill” that means the wheel will not lose the contact with the track even when there is a major defect in the track. Thus the design improves the safety of running.

Primary springs:

The primary springs are spiral, steel springs mounted between the bogie frame and the axle bearing houses. Designing the springs allows the regulation of the rotation of the axle bearing houses ie the “off-road skill”.

Side-bearer and the secondary springs:

The weight of the body of the coach is conveyed to the bogie frame by two rubber-steel sheet spring. This secondary spring ensures that the bogie can rotate compared to the body frame in a curved track and after the curve has ended it ensures that the bogie returns its original position. The benefit of this design compared to the traditional side-bearer is this solution does not need lubricant nor maintenance. Beside it is environmentally friendly it has quite good vibe and noise absorption, that highly improve the passenger comfort.

Draw-gear:

The draw-gear conveys the longitudinal forces (traction force, breaking force) between the bogie and the body frame. The draw-gear is “Z” shaped, which consist of a bogie-bolster, perpendicular to the working direction, and two draw-bar parallel with the working direction. The draw-gear is rigid in longitudinal way, however it ensures the rotation of the bogie and a slight horizontal movement of it. The benefit of the “Z” shaped design is this design does not convey minor track defects from the bogie to the body frame, thus it improves the passenger comfort. Further advantage of the “Z” shaped design is this allows a smooth transition to the body frame from a straight track to a curved track, improving the passenger comfort even further.

Brake set:

The brake set is traditional, it has got brake-block and brake-rigging. The wheels are braked one side, from the center of the bogie.