In February 2012, Voith (Pty) Ltd, together with VDL, supplied the 150th DIWA 854.5 automatic transmission to the bus operator, Metro Mass Transit LTD, based in Ghana.
“We supplied the first DIWA transmission to the bus operator in January 2009, (in accordance with the original order which was placed with Voith Germany),” says Anthony King, from Voith South Africa’s Road division. Africa is notorious for poor, unsealed road conditions and city congestion Ghana is certainly no exception. A minimum standing, and maximum seated passengers approach is the order of the day with multiple stop-starts in inner-city traffic. The required acceleration, gear shifting and braking place high demands on bus components. The numerous unique features of the economical DIWA transmission reduce wear and tear and extend component service life that ultimately translate to cost and energy savings that not only benefit operators but also help to reduce the carbon footprint. 2/…150th Voith DIWA Automatic Transmission_Ghana The DIWA power-split principle makes it the ideal automatic transmission solution for buses with engine torques up to 1900 Nm with CAN (Controller Area Network) and EDC (Electronic Diesel Control) as it allows smooth acceleration across a speed range where other transmissions need to shift gears two or three times. King explains, “The long first gear of the Voith DIWA transmission gives it a very smooth jerk free shift and offers an advantage over similar products by allowing for optimum passenger and driver comfort. Reduction in gear shifts means less wear, extended service life and improved economy for the operator.”
DIWA’s built-in secondary retarder offers further cost savings; the DIWA principle allows driving and braking with one hydraulic circuit. This ensures the quickest response time of the secondary retarder which is important at high speeds. By slowing the bus down before braking, less energy is used on the primary braking system; there is less wear and tear on the brakes which increases the life of the brake linings, reduces maintenance and down time, King points out that it is also an important safety feature.
Due to the DIWA’s robust cooling system there is less oil degradation. This allows for less cooling fan engagement. The result is lower fuel consumption as well as reduced oil ageing which extends the overall bus service life and reduces downtime. The bus company (Metro Mass Transit LTD) is responsible for maintenance on the DIWA transmissions and their technical staff received full training from Voith SA. Voith technicians, based at head office in Johannesburg, are also ready to lend support if required. King, states that MMT is extremely satisfied with the performance of the DIWA transmission, reporting (three years of) trouble-free operation since introduction. 3/…150th Voith DIWA Automatic Transmission_Ghana There are over 200 000 buses worldwide that are fitted with DIWA automatic transmissions from Voith. “Optimum passenger and driver safety and comfort, high availability, low maintenance and operator costs make the DIWA the ideal BRT solution,” concludes King.
