Extending Wheel Life             Special to Passenger Transport ~ PASSENGER TRANSPORT October 11, 1999

VANCOUVER, B.C. Wheel wear is a concern on most metro systems. But when the Prague Metro in the Czech Republic discovered that wheel sets on its 500-car fleet needed to be replaced after only 150,000 kilome­ters of service, the system sought a solution, ultimately finding it with Kelsan Technolo­gies Corp.

Prague Metro is a burgeoning 50-km sys­tem serving more than one million passengers a day, but as its vehicle traffic increased, so did wheel wear. At one point, excessive wheel flange wear required cutting, or re-truing, of the wheels at 50,000 km intervals and replacement at 150,000 km.

"In most cases, wheel sets did not last from one scheduled maintenance to the next one," said Josef Nemecek, chief of Prague Metro's Rolling Stock Division.

The system saw wheel lubrication as a potential solution to the wheel wear problem, first experimenting with Russian-designed oil-filled wick type lubricant and

traditional North American piston-type wayside lubrica­tors. When these methods failed to appreciably extend wheel life, the Metro decided to test Kelsan's LCF (Low Coefficient of Friction) solid-stick, vehicle-mounted lubrication system.

Early favorable results led the Metro to equip all trains on its Line B--its newest line, and the one with the greatest flange wear with tile Kelsan LCF system. Solid-slick LCF lubricators were mounted on the leading and trailing axles of each of the five car trainsets operating on the line, and on one wheelset on the middle car.

Increased Wheel Life

As the Prague Metro closely monitored wheel wear on the LCF-equipped trainsets, positive results soon became apparent. After approximately 12 months of operation, the trainsets exhibited wheel flange wear of about 4.5 mm at 150,000 km--a threefold extension in wheel life over the non LCF equipped cars. Wheels with a total 150,000 km life, and re-truing at 50,000 km intervals, were now seeing 150,000 km of service before re-truing was even required, Nemecek said.

Further testing continues to yield impres­sive results. Analysis of current wheel wear trends indicates that wheels on LCF-equipped trainsets exhibit approximately 3 mm of wear after the first 80,000 km to 100,000 km of operation. "After that," Nemecek said, "wear slows down to approximately 1.5 mm for each 100,000 km."

Wheel truing cycles on the Metro have been extended from 50,000 km to between 200,000 and 250,000 km. Overall wheel life has been increased from 150,000 km (with three re-truing cycles) to an anticipated 800,000 km (with four to five re-truing cycles)--an increase of more than five times in wheel life.

The improved performance and increased wheel life on the LCF-equipped trainsets has made a believer of the chief of the Metro's rolling stock division. "After Line B results," Nemecek said, "cars on the other lines will also be gradually equipped."

Kelsan develops Advanced Technology Friction Management SolutionsTM for transit, freight rail, and industrial customers. Kelsan products increase or decrease the friction between moving parts as required. The company holds 15 patents and has another 15 patents pending.