The Voith DIWA automotive transmission was designed by Voith primarily for city-buses and suburban buses. The transmission utilizes a Differential-Wandler (Converter) or DIWA which replaces two gears which would be used on a conventional transmission. Voith has designed many variations and generations of the Voith DIWA.
History Evaluation
DIWA (D851/D854/D854G) 1976-1990
Three/four front speed, four-speed G version (for example, D854G on some KMBMetrobus ), which add a set of 1.36:1 reduction gear to the output
Three-stage throttle sensor (there are two switches on the inside), the throttle depth corresponding to each stage needs to be manually adjusted
The shifting speed is divided into four stages with the same force (three-stage throttle + kickdown)
The hydraulic retarder will go out when the vehicle speed is too low, and it will turn a gear at the same time.
All oil valves are on-off, and the force of biting the clutch is controlled by adjusting the working/o of a gearbox.
Uninterrupted throttle sensor (at least seven-stage throttle + kickdown) / signal by the trip computer
Newly added input speed sensor and back gear planetary gear ring speed sensor, the former is used to check the difference between input and output speed when rotating the gear, while the latter is used to check the back gear planetary gear when the retarder is locked for more precise control.
The hydraulic retarder will go out when the vehicle speed is too low. After turning back for a gear, gently bite the back gear and slow down.
The oil circuit is controlled, especially the oil pressure of the torque converter is controlled.
Most oil valves can sense independently to control the output oil pressure (any 0-100% of the operating pressure), and the clutch force more efficiently. The operating pressure always keep at 100%. Therefore, no need for accumulation delays.
D381.4 is D851.3E with a different planetary gear and input flange configuration for the Volvo B10M.
DIWA.5 (D824.5/D854.5/D864.5/D884.5)
Deleted three-speed version due to high speed fuel wasting
(e.g. the D863 rotates at 2500rpm while D864 rotates at 1700rpm when the bus is at 70km/h)
offering with six types of pump wheels: L, F, G, V, X, H
DIWA.6 (D824.6/D854.6/D864.6/D884.6)
Stop-Start System added
The operating pressure will be adjusted according to the road situation. It is necessary to increase it at first, which can reduce unnecessary load of oil pumping and save fuel.
DIWA.NXT
added for additional overdrive gear, retarder and mild hybrid systems
up to 16% fuel savings then DIWA.6
Gear ratios
D200, D506 (wide-ratio)
1
2
R
1.97
0.95
3.80
D501, D506 (close-ratio)
1
2
R
1.39
0.85
3.80
D854 (D851 is 3 forward+reverse with the same ratios), DIWA.4
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