Background Art The length of integral rail car body is limited by car body narrowing, which depends on the possibility of passage through a traction line curve. This length is approximately 15 meters at tram cars due to city trafic.

This length does not provide for sufficient low-floor proportion design in the passenger space. For this reason, partly low-floor tram cars are usually designed as articulated trams, which allow better guiding in curves and, even at significantly higher body length, the body narrowing remains in acceptable range.

On the other hand, an articulated car body has more degrees of freedom thus requiring additional technical means, which would uniquely define its position in curves. These means may include an additional undercarriage, linkage mechanism or usage of fixed undercarriages. Utilisation of additional undercarriage can be justified at longer cars, however, this equipment is too expensive for shorter cars. For this reason, shorter cars (with length below approximately 20 meters) usually utilize linkage mechanism solution (at two-piece bodies) or the solution with fixed undercarriages (at three-piece bodies). Due to prevention from free undercarriages rotation, solutions with fixed undercarriages are characterized by increased steering forces and with resulting reduced derailing safety, increased wear of wheel flanges and they are not therefore suitable for classical city-type tram lines with numerous curves without transition curves. Instead, they more suitable for high-speed type tram lines. Besides, solutions with additional linkage mechanism are not suitable for low-floor cars due to space limitations.

Disclosure of Invention The above listed limitations are eliminated by the equipment for mutual turning of car body elements. With this solution, an articulated car body rests on freely rotating undercarriages and adjacent body elements are connected with articulated joint. The principle of the articulated joint consists in force element arrangement in the area of body elements articulation when supporting points are anchored on adjacent body elements and action of force element thus depends on mutual displacement of undercarriages and articulated body. Each undercarriage is fitted with undercarriage displacement sensor and each articulated joint between body elements is provided with body displacement sensor. Body undercarriage elements do not have to be adjacent and there may be an element without undercarriage nested between them. The force element comprises a linear drive and attache mechanism. It acts in predefined dependence on signals of the above mentioned sensors and according to the control unit response. The undercarriage displacement sensor detects the displacement of rotating undercarriage and car body element and sends a signal to the control unit. Car body displacement sensor detects the displacement of body elements in the area of articulation and sends a signal to the control unit.

The solution described herein does not require increased driving forces during body swiveling and undercarriages may rotate freely. This results in improved driving properties of tramway car and in avoiding undesirable excessive wear of wheel flanges and rails in turns.

Brief Description of the Drawing Figure 1 shows section plan of the tram car equipped with equipment for mutual turning of car body elements.

Detail Description The attached Figure 1 shows two-part tram car body with first element No. 8 and second element No. 9 which, together with adjacent body element No. 13 rotate on a vertical axis formed by articulation of No. 10 of adjacent elements. Both body elements are based on freely rotating undercarriages (first undercarriage No. 6 and second undercaniage No. 7) equipped with the equipment for mutual turning of car body elements comprising one force element No. 1 situated in skew position with respect to the axis of adjacent elements articulation No. 10. The force element is installed on both the first body element No. 8 and the second body element No. 9, which also adjoins the body 13. The first support point No. 11 of the force element No.

I is anchored on the first body element No. 8 and the other supporting point No. 12 of the force element No. I is anchored on the next element of body No. 9. Action of the force element No. 1 is based on mutual displacement of the first undercarriage No. 6 and the first body element No. 8 and me second undercarriage No. 7 against the other body element No. 9. If a rail vehicle enters a curve and once the first rotating undercarriage No. 6 turns against the first body element No. 8, the displacement sensor No. 3 of the first undercarriage No. 6 sends a signal into the control unit No. 5. After processing with a built-in algorithm, the control unit immediately issues a command into the force element No. 1 and the rail vehicle body is displaced correspondingly.

Body displacement is concurrently controlled by a signal from elements displacement sensor No. 2, which is sent to the control unit No. 1. The control process is also influenced by entry of another undercarriage No. 7 into the curve and by corresponding signals from the displacement sensor No. 4 of the undercarriage No. of the undercarriage No. 7 into the control unit No. 1. The equipment for mutual turning of car body elements works analogously when the vehicle drives out from the curve.

This way, the car body elements are appropriately turned in curves and aligned in straight sections thus optimizing their guiding in curves.

Industrial Application The equipment for mutual turning of car body elements can be conveniently used at articulated bodies of rail cars, mainly at low floor trams.