LEG Firm, Limited Liability Company

Director - Viktor D. Avramenko

Company "LEG" Ltd (Ukraine, Kharkiv) was founded in January 1993.
Its profile activity is the production of graphite and carbon based materials and products (mainly, electrical brushes and contact inserts for trolley buses). Since 1997 our company has been a member of the Association of municipal enterprises of local electric public transport, which incorporate the representatives of all the counties of the former USSR. Since that time the initiative certification of brushes has been performed according to the requirements of UkrSerpo system. The company is a member of the Kharkiv Chamber of Commerce & Industry, Ukraine.

Now the staff of the company consists of 45 employees. The director and technical managers of the company are the graduates of the Kharkiv State University (Physical and Technical Department), the principal experts of the National Scientific Centre "Kharkiv Institute of Physics and Technology " (NSC KhIPT). There they spent 10-15 years developing special-purpose carbon-graphite materials.
The engineers of the company, including the Chief Engineer are the graduates of the most prestigeous colleges of the former USSR who have more than 15-year experience in the development of equipment for carbon materials production processes, including ones for rocket technology. Most of production engineers are the former workers of the Experimental Plant of NSC KhIPT that manufactured carbon materials.
Using high professionalism of its experts, "LEG" Ltd offers to its consumers finished products of improved quality. The financial and technical policy of the company is oriented to perform its own technological investigations and to fund (the company allocates nearly 95% of profit to its production development) the production of electrical brushes and contact plates every year and to design and to launch the production of new kinds of products without financial support.

BRUSHES
"LEG" began to produce electrical brushes in 1993. Developed by the experts of the company, the production processes are unique in the world. At the beginning of 1995 under the support of Kharkov State Enterprise "Gorelectrotrans" our works was put into operation, but the production of the high-quality products became possible only in July 1996 when all the necessary technological equipment was put into operation and quality control system of the finished good was organised. At that stage the company has got the support from Kharkov and Kiev Underground Technical Services in the adaptation of our technologies for production of electrical brushes for underground car traction engines instead of Russian analogues made of EG-841 material. All new designs of the company are testing on the stand motors of Scientific Research Institute "Electrotyazhmash", who has been supporting the company for a long time.
Ukraine State Standard approved the technical specifications TU U 14111810.001-95 (effective date 01.07.95) "BDH Brushes for Vehicle Electrical Machines".
"LEG" produces its own materials, brands BDH-30, BDH-40 and BDH-50, instead of Russian analogues of series EG. To our knowledge our electrical brushes are the only ones which were voluntarily certificated for using for the railway transport.

CONFORMITY TABLE OF BDH ELECTROBRUSH MATERIAL (HALF-FINISHED PRODUCTS) TO ELECTROBRUSH MATERIAL (HALF-FINISHED PRODUCTS) OF ELECTROGRAPHITIC CLASS

The company specialists took into consideration the following circumstances when own electrical brushes production was organized:
1) Traditional technologies used by the largest world manufacturers of brushes are very power-consuming because they include the stage of roasting of materials (heating to about 1200 0C) and graphitization (heating up to more than 2500 0C).
2) According to the traditional methods of production highly expensive material-consuming equipment is used.
3) The main volume (according material mass) of electrical brushes on the market is electrographitic ones used for more than 1 kW power collector motors and generators.
Taking into account the above mentioned considerations we decided to develop the production of brush materials with electrical parameters typical for electrographitic brushes, but using considerably lower power-consuming technologies and more expensive initial material components: graphitic carbon materials instead of the traditional cokes, blacks and synthetic binders instead of pitches.
Then we made the analysis of assortment of brush materials of electographitic class which are quantity-produced all over the world. It is found that all manufactories of these materials produce a lot of materials that differ by their electrophysical properties by several per cents. Nevertheless, the designers of electrical machines never could simply define with 100 % guarantee the brush grade needed for the given machine. In each case electrical brushes were selected experimentally from materials having similar characteristics.
On the base of the analysis results the LEG specialists selected 3 types of the materials of electrographitic class, which differ by their functional application:
1. Materials intended for generator and synchronous motor rings (Russian analogues EG4, G3, 611OM)
2. Materials intended for the work on generator and unloaded motor collectors (Russian analogues EG14, EG71 ..)
3.. Materials intended for the work on motor and generator collectors under severe commutation conditions (Russian analogues EG61A, EG74, EG84-1, EG75, EG85).
"LEG" attempted to make unification of the produced materials: production of BDH30 material instead of the 1-st type materials; BDH40 and BDH40-F instead of the 2-nd type materials and BDH50 and BDH50-F materials instead of the 3-d type materials.
Such a radical decision could have been realized due to the technological opportunity to receive the materials with anisotropy of electrophysical characteristics. The choice of the brush material from the set of standard electrographitic materials was always the result of compromise between the providing of good commutation conditions (high electric resistance, large contact resistance on pair of brushes) and the demanding of the low power-releasing in brush-collector assembly (low electrical resistance, low voltage drop on pair of brushes). In materials of BDH series produced by "LEG" this compromise may be avoided because electrical resistance of BDH materials in the direction of r (from the shunt to the collector) is minimum 2.5 times less than in the direction t (direction of collector rotation).
Thus, with the equal power releasing in the brush-collector assembly in comparison with the standard materials, BDH materials have much better collector characteristics.
In conclusion we want to note that BDH40-F and BDH50-F materials developed by "LEG" specialists retaining working ability at temperature of 145 0C and BDH30-SF material retaining working ability at current density 25 A/sq. cm have no analogues among materials produced by Russian electrotechnical industry.

Trolley Contact Inserts
LEG began production of contact inserts for current collector heads in November 1995 responding to the request of Kharkov GKP "Gorelectrotrans" who was not satisfied with the quality and price of the inserts produced by Kharkov Electrotransport Plant (the former VARS). Using some technological decisions which were used during the production of electrical brushes and developing together with the compression moulding method (VKT-1 inserts) the extrusion production method (VKT-2 inserts) the Company already in January 1996 could completely meet the requirement of Kharkov GKP "Gorelectrotrans". Since 15-th May 1996 "LEG" is the only Ukrainian manufacturer realizing the output of products according to the current technical specifications. In 1998 the Company developed the production and began to manufacture "all-weather" metal-graphite inserts of new VKT-1M, VKT-3M and VKT-5M class.