INTRO: As builders move towards subcontracting larger modules as complete units, Voith Turbo has launched a range of complete power packs and uprated its hydraulic transmissions for higher performance. Harry Hondius MSc reports from Heidenheim

WITH A turnover of €3·3bn in 2003, Voith AG employs 24000 staff around the world. It is active in paper-making machines, drivelines and turbines, as well as its involvement in the rail, bus, marine and industrial sectors through drives specialist Voith Turbo GmbH & Co KG. This has around 4000 staff and a turnover of €651m in 2002-03.

In recent years Voith Turbo Rail has expanded through the acquisition of mechanical drives group BSI and coupler specialist Scharfenberg. This has broadened the company’s transmission range into a complete family, covering hydrodynamic transmissions, cooler groups, cardan shafts, torsion dampers, gears and axle drives and couplers. Turnover for the rail business in 2001-02 was €220m. Of this 36% came from the Scharfenberg product lines, 34% from hydraulic transmissions, 16% from mechanical drives and the remainder from services and spares.

Voith enjoyed long-term support from German Federal Railway, which for many years relied exclusively on 1500rev/min diesel engines and hydrodynamic transmissions. At one time DB accounted for more than 75% of Voith’s rail business, but orders fell away after 1978 because all steam traction had been replaced and because of increased competition from electric drives.

Today General Motors and General Electric dominate the market, producing around 1400 diesel-electric locomotives each year. These are split between DC and AC drives, but their performance seems to be quite similar. Modern electric transmissions offer advantages in better adhesion characteristics, lower fuel consumption at light and full loads, high electric braking power and the sturdiness of the medium-speed engines. By contrast, hydraulic transmissions allow better power-to-weight ratios, and often a lower price, and reduced risk from obsolescence of electronic parts.

Over the 20 years up to 1995, Voith Turbo Rail relied primarily on the DMU market, with turnover ranging between €15m and €30m. Voith is now the only supplier of hydraulic transmissions for the railcar sector. At the smaller end of the range, its DIWA bus transmissions compete with Allison and ZF hydromechanical transmissions. Alstom, Bombardier and Siemens also compete in the European DMU and locomotive markets using electric transmissions.

From 1996 onwards Voith’s sales began to grow strongly. The newly-developed T211 converter with coupling and optional retarder transmission attracted several large orders. SNCF adopted it for X72500 and X73500 TER diesel railcars, and Netherlands Railways for the DM90 units. British rolling stock leasing companies chose the T211 for Class 168, 170, and 175 DMUs.

In Belgium, SNCB specified the more powerful T311 converter for its Alstom-built AR41 DMUs. More prestigious diesel units projects such as the VT 611 and 612 in German and the First Great Western Class 180s employed the T312bre converter with twin couplings and a retarder transmission, giving better efficiency over the higher speed range up to 200 km/h.

On top of this has come since 1999 an increasing volume of orders for shunting locomotives, and practically every freight loco built by Vossloh. Estimated turnover for the hydraulic transmissions business in 2003-04 is put at almost €70m. In the last financial year, the biggest customer was Bombardier (33%), followed by Vossloh (21%), Alstom (17%) and Siemens (5%).

Fighting the competition

Around 6% of Voith Turbo’s turnover is dedicated to research and development. Last year the company launched a super-compact transmission to compete with electric drives and meet increasing demand from the DMU sector. The T111bre is designed for an input of 300 kW, or 2100Nm (Fig 1). Feedback indicated that bus transmissions like the DIWA 864.3 were not suited to long periods of running at full load, as required in rail traction applications.

Through refinements of the fluid flow in the converters and coupling, the input for the T311bre and T312bre has been raised to 650 kW. Similarly, the rating for the T211bre and T212bre has been raised to 450 kW. At the same time, all these transmissions have been developed to operate for up to 1·4 million km between overhauls, depending on the load cycles.

An important market trend at present has seen the bigger systems integrators increasingly choosing to have important parts of their trains developed completely by subcontractors. To suit this trend, Voith Turbo has decided to offer a range of powerpacks to DMU suppliers, fully assembled from Voith components. Three of these powerpacks are are now under development and test: