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Engine rpms in DMUS

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hwl

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Exactly, which I assume is how the transmission is set up with the different variants of the 158s as well with their different engine speeds.
Nope!!! they all have the same final drives/ratio (3.10) but slightly different T211 set ups (different fixed gear ratios inside the voith box).
The simple final drive ratio change approach only started with 165s/166s (same T211 for both 75/90mph), 150-156s have 3.01 final drive ratio (3% difference vs 158 but 20% would be needed to do it in the final drive alone) and a different Voith T211 setup to the various 158/159s
 

hexagon789

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Nope!!! they all have the same final drives/ratio (3.10) but slightly different T211 set ups (different fixed gear ratios inside the voith box).
The simple final drive ratio change approach only started with 165s/166s (same T211 for both 75/90mph), 150-156s have 3.01 final drive ratio (3% difference vs 158 but 20% would be needed to do it in the final drive alone) and a different Voith T211 setup to the various 158/159s

So different ratios but not of the same transmission part.
 

37057

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Just to avoid any further confusion the hydrodynamic gearbox alone is generally referred to as the transmission and the final drive gearboxes are referred to as that. Calling the lot the transmission leads to confusion.
 

hexagon789

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Just to avoid any further confusion the hydrodynamic gearbox alone is generally referred to as the transmission and the final drive gearboxes are referred to as that. Calling the lot the transmission leads to confusion.

But surely as they entire thing transmits the engine power to the wheels it is reasonable to call the entire lot the transmission?
 

37057

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Depends if you'd rather confuse people. Everyone I know who works on them refer to them separately for this reason.
 

hexagon789

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Depends if you'd rather confuse people. Everyone I know who works on them refer to them separately for this reason.

Don't get me wrong I can understand differentiating them but surely it would be easier to do that by referring to them by their actual names and then collectively as the "transmission".
 

37057

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Don't get me wrong I can understand differentiating them but surely it would be easier to do that by referring to them by their actual names and then collectively as the "transmission".

People do, transmission is the transmission and the final drives are the final drives!

Collectively known as... Driveline...
 

hwl

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Don't get me wrong I can understand differentiating them but surely it would be easier to do that by referring to them by their actual names and then collectively as the "transmission".
Except Voith refers to the Torque converter /hydrodynamic drive / reverser / reduction gears as the "Transmission" (ditto ZF for the mech boxes) and Gmeinder (paired with Voith transmissions) /ZF describe the final drive gear box (on the axle) as the "final drive" hence most people follow that convention!
 

hexagon789

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People do, transmission is the transmission and the final drives are the final drives!

Collectively known as... Driveline...

Fair enough.

Except Voith refers to the Torque converter /hydrodynamic drive / reverser / reduction gears as the "Transmission" (ditto ZF for the mech boxes) and Gmeinder (paired with Voith transmissions) /ZF describe the final drive gear box (on the axle) as the "final drive" hence most people follow that convention!

Just adding to the confusion! :lol:
 

37057

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To separate things further, the EMU equivalent of a final drive is often referred to as just "Gearbox".
 

hwl

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To separate things further, the EMU equivalent of a final drive is often referred to as just "Gearbox".
But most EMU gearboxes (i.e. all except Voyager /Meridian) and most locomotives are just straight cut gear to gear direct drives with no change in alignment of axis of motion where as DMU final drives (and voyager /Meridian / Cl91) convert the rotation through 90 degrees (and often drive 2 axles/ bogie with a master and slave final drive) hence the differentiation between gearbox and final drive.
 
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37057

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A more interesting thread topic would be "Traction Motor speed at top speed"...

Desiros are double reduction and from what I've seen when they're moving low speed they don't half shift. Need to dig the OEM docs out.
 
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