Voith DIWA

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The Voith DIWA automotive transmission was specifically 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. It has several generations - all of the automatic transmission type with many variants:

History Evaluation[]

DIWA (D851/D854/D854G)

• Three/four front speed, four-speed G version (for example, Metroliner D854G), 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 turning wave speed is divided into four stages with the same force (three-stage throttle + kickdown)

S, N two kinds of pump wheels

• The hydraulic retarder will go out when the vehicle speed is too low, and it will turn a wave 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.

DIWA 2 (D851.2/D854.2/D854.2G/D863/D864)

• T0, T1 two types of turbines, R0, R1 two types of rear wave planetary gears

Hydraulic retarder can be used to stop

• Automatic empty wave when parking

• Individual oil valves can be operated between torque converter pressure and operating pressure, whichever is higher

DIWA 3 (D823.3/D851.3/D854.3/D863.3/D864.3/D883.3/D884.3)

• No G version

• Brand new gearbox computer, you can use the computer to tune the gearbox

• Uninterrupted throttle sensor (at least seven-stage throttle + kickdown) / signal by trip computer

• Newly added input speed sensor and back wave planetary gear ring speed sensor, the former is used to check the difference between input and output speed when rotating the wave, and the latter is used to check the back wave planetary gear when the retarder is locked for more precise control.

• Clutch strength,

The speed of the rotating wave is continuously variable with the same strength (calculated by the gearbox computer)

• F, G, V, X, H five types of pump wheels

T0, T2, T3 three kinds of turbines, R0, R2 two rear-wave planetary gears

• The hydraulic retarder will go out when the vehicle speed is too low. After turning back for a wave, gently bite the back wave and slow down.

• The oil circuit is controlled, especially the oil pressure of the torque converter is controlled.

• Most oil valves can independently sense and control the output oil pressure (any 0-100% of the operating pressure), and control the clutch force more accurately and timely. The operating pressure is always kept at 100%, so there is no need for accumul.

DIWA.3E (D823.3E/D851.3E/D854.3E/D863.3E/D864.3E/D883.3E/D884.3E)

• Additional SensoTop

With converter fill control function, a valve is added to intercept the torque converter's oil, so the torque converter's input oil can be discharged after the speed is high enough up and down, and the retarder will lock the rear clutch first. The turbine spins and the oil re-enters.

DIWA.5 (D824.5/D854.5/D864.5/D884.5)

• Full-line of four-speed version

• Six types of pump wheels: L, F, G, V, X, H

T0, T2 two types of turbines.

DIWA.6 (D824.6/D854.6/D864.6/D884.6)

• Stop-Start System added

• The operating pressure will be adjusted according to the situation. It is necessary to increase it first, which can reduce unnecessary load of the oil pump and save oil.

Principle of Operation[]

During Starting, the proven DIWA power split principle comes into action. As soon as the vehicle begins to move, power is divided steplessly between the hydrodynamic and the mechanical transmission of torque. In 1st gear, the DIWA range, input clutch and turbine brake are closed. The engine torque is directly transmitted to the outer rim of the differential. The impeller and the pump shaft is driven in opposite rotary directions via the planetary gears of the differential. During this process, the output and hence the planetary carrier remain stationary. In the converter, oil delivered by the impeller flows through the guide wheel to the turbine wheel in a closed circuit. The torque that is delivered and converted, that is increased, is transmitted to the planetary carrier via the sun gear of the turbine gear. The planetary gear shaft transmits both the torque of the input differential, that is the purely mechanical share, and the torque of the turbine gear, that is the hydrodynamic share, directly to the transmission output.^[1]

From 2nd to 4th gear, in contrast to 1st gear, power transmission occurs purely mechanically. The transition from 1st gear into 2nd gear occurs automatically, independent from driving speed and the driving pedal position. The hydrodynamic power transmission is switched off in 2nd gear. This occurs by the pump brake being closed, which stops the impeller. At the same time, the turbine wheel is not transmitting torque to the turbine gear due to the open turbine brake. The transmission ratio of the 2nd gear corresponds to the input differential. When changing from 2nd into 3rd gear, the input clutch opens and the lockup clutch, is shut. As a result, the drive shaft is, by the outer rim of the locked up clutch, directly connected with the planetary gear shaft, and thus the output shaft. The ratio is now 1:1. Depending on the position of the accelerator pedal, the vehicle load and the topography, the shift from 3rd to 4th gear occurs automatically. During this transition, the locked up clutch opens while the coupling for the 4th gear, the fast release coupling, closes. 4th gear is overdrive, with the ratio of 0.7 or 0.73 depending on the differential.^[2]

In order to activate the retarder in the mechanical gears 2 to 4, the reverse gear brake, is closed. As a result, the turbine wheel is accelerated by a correspondingly high ratio and driven in 1st gear against the rotary direction. The turbine wheel now acts as an axial pump which delivers oil against the guide wheel and the braked or stationary impeller. During this process, kinetic energy is converted into heat which is dissipated by the heat exchanger. The vehicle is braked.^[3]

ANS stands for automatic neutral shift at standstill by opening the input clutch, the converter is fully decoupled from the input shaft. As a result, the power flow between engine and transmission is automatically interrupted when the vehicle stand while the engine keeps running. The ANS function is automatically activated both at bus stops and stops at red traffic lights which reduces fuel consumption during these operating conditions.^[4]

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

1	2	3	4	R
5.200	1.360	1.000	0.735	3.800

DIWA.5, DIWA.6

1	2	3	4	R
5.200	1.429	1.000	0.700	4.120

See also[]

• List of Voith transmissions
• List alternative transmissions

References[]

"Voith 506 Document" (PDF). Voith. Voith. Retrieved 24 October 2013.

"DIWA.3E, E 200, DIWAGNOSIS - The Combination for Economic Operation". Voith. Voith. Retrieved 24 October 2013.