Cutting noise and smoothing the ride
Commercial demands for a better ride and political pressure to reduce lineside noise present engineers with fresh challenges in bogie design
NYCT tries Adtranz bogies
A PAIR of prototype powered bogies designed by the Adtranz bogie office in Siegen were fitted to a New York City Transit subway car in May (photo), as part of a process which could see the company accredited as an NYCT approved supplier.
New fabricated frames were manufactured by the Adtranz bogie Product Unit at Derby, and fitted with motors, gearboxes, wheelsets and brake equipment recovered from a pair of older NYCT cast-steel bogies. Following approval by NYCT staff, the rebuilt bogies were shipped back to New York for installation.
The Derby PU has won an order to supply 208 Metrostar bogies for the trainsets which Koros of South Korea is building for Hong Kong MTR Corp's Tseung Kwan O extension. Derived from the Adtranz U series platform with fittings from the Series 3 design, the new bogies are due for delivery from the end of this year. They will have anti-roll bar assemblies supplied by Silvertown UK Ltd which include a torsion bar, forks, and an innovative Silentbloc ball joint at each end of the vertical links. This contains a rubber element which is designed to deform radially, torsionally and conically to absorb a variety of forces.
Also being assembled at the plant are bogies for the fleet of 'Contessa' cross-Øresund EMUs which Adtranz is supplying to the Swedish and Danish state railways (RG 7.00 p420). n
Bonded rubber suspensions
GERMAN suspensions specialist Gummi-Metall Technik of Bühl has launched a new range of primary suspensions for light rail vehicles, designed to minimise the degree of creep between the bonded steel and rubber surfaces. In a typical application with 16 kN loadings, creep was formerly expected to reach 9mm after a life of around 10 years. In the last three years, this has been reduced to 3mm, and GMT anticipates that its latest design will achieve 1 to 1·5mm. At the same time, the diameter of the suspension unit is reduced from 180 to 150mm.
GMT has also launched a patented design of super-resilient wheels with a fully-bonded 360í annular pure shear ring. This augments a range of components which includes large-diameter bonded rubber discs for use in pure shear applications, pure rubber blocks for areas of full compression, and rubber V-rings for specialist designs.
The fully-bonded annular design offers reduced transmission of noise and vibration, between 5 and 25 dB(A), lower levels of acceleration transmitted back into the bogie, and easier installation and maintenance. These are expected to produce significant savings in life-cycle cost.
CAPTION: As part of its comprehensive noise-reduction programme, Swiss Federal Railways has started rebuilding trailer bogies for its regional EMU sets at Olten works. Welded frames are replacing fabricated assemblies, and composition brake blocks are used in place of cast iron. The target of the programme is to halve the external noise level compared to the original 35-year-old vehicles. Over 120 coaches have been rebuilt so far, and another 70 are to be treated by the end of this year. By 2004 SBBplans to have modified the rest of its passenger fleet to meet recently imposed noise restrictions
B5005 to carry non-tilt Voyagers
CURRENTLY ON TEST in Belgium is the first 200 km/h Voyager DMU being built by Bombardier for Virgin Trains (p492). The 136 non-tilting cars formed into 34 four-car units are due into fleet service next summer, where they will be deployed initially between Birmingham and Brighton.
They will be followed into service by 216 SuperVoyager cars capable of tilting 6í, allowing Virgin's CrossCountry franchise to retire its current rolling stock fleet by 2002. These will use the well-proven Y36 bogie with hydraulic tilt actuation.
Bogies for the Voyager fleet are being manufactured at Crespin in France to a lightweight design. Designated B5005, this is a development of the B5000 bogie produced in 1991 by RFS Specialist Rail Products in collaboration with British Rail Research for the Networker EMUs and DMUs being ordered in quantity by BR's Network SouthEast business (RG 3.91 p125). Initially used under trailers, a powered version with AC motors and 25 tonne pivot load followed in 1994.
In the Voyager application, every car has a Cummins underfloor engine and alternator supplying power to a pair of body-mounted traction motors. Each drives one inner axle through a cardan shaft and axle-mounted final drive gearbox. Thus all 272 bogies are identical.
This arrangement has been adopted to minimise unsprung mass and thus contribute to an exceptionally low bogie weight. A primary objective of the B5000 programme was a 30% weight reduction compared to the BT13 that it replaced. As reported by Bombardier's Director, Bogie Design, Eddie Searancke at the IMechE Wheels & Axles seminar on May 19, it was demonstrated that lower sprung and unsprung forces reduced the cost of track damage by 40%.
The use of inboard journals, a 60% reduction in frame mass, and shorter hollow axles were the principal factors contributing to this remarkable result. The primary suspension is a simple free-rubber Metacone, with longitudinal traction rod, that sits directly on top of the axleboxes and eliminates the need for hydraulic dampers.
Bombardier has upgraded the original BR specification to permit 200 km/h operation of the B5005 with one driven axle, and 225 km/h when used under trailer cars. This has required a new secondary air suspension with higher performance to meet the ride quality specified. Rubber Metacones with an emergency vertical damper permit degraded operation if an air-spring deflates.
The bogie wheelbase is 2250mm, and new wheel diameter is 780mm. Ventilated one-piece brake discs of 645mm diameter are secured to each wheel web.
As trackside hotbox detectors are set to scan outboard journals, fusible plugs melt if the axlebox overheats. This results in a loss of air pressure that triggers a warning light in the cab.
- CAPTION: Bogies for the Juniper EMUs which Alstom Transport is supplying to British train operators South West Trains, Gatwick Express and ScotRail are being manufactured at the company's specialist bogie plant in Le Creusot, France. The Gatwick Express Class 460 EMUs were epected to start carrying passengers in mid-July
ICE bogies get quieter
The research department of German Railway has been working with its principal suppliers to optimise its bogies and wheelsets to minimise acoustic transmissions. The latest ICE500 bogies supplied by Siemens-Duewag for the ICE3 high-speed trainsets were subjected to a comprehensive noise management review at the design stage. Optimising individual components throughout the train has reduced lineside noise by 25 times from 96 to 82 dB(A)
CAPTION: Bogies for the Virgin West Coast 225 km/h Pendolino Britannico tilting EMU fleet are being supplied by Fiat-SIG for installation on the trains during final assembly at Alstom Transport's Washwood Heath plant; wheelsets are supplied by Lucchini of Italy. One vehicle was fully instrumented for the start of static tilt tests in June (RG 7.00 p 405)