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Class 175 (and 180) "Boost mode"

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hexagon789

hexagon789

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I read that as built the Class 175s (and possibly 180s for that matter) were equipped with a "Boost" function which operated when Notch 4 was selected on the TBC.

I believe this has long been isolated, possibly before entering passenger service I'm not sure, but does anyone know how it would have worked, did the engines simply rev up more or was it something else?

Regards Hexagon789.
 
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Erniescooper

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The 175 has a Traction Boost function that will re-rate the engine to 510 hp for 20 minutes at a time and will load shed the three phase functions of the HVACs by dropping out contractor TBST which will also drop out in the event of the alternator overheating. The 180 only the contactor TBST part of the circuit to protect the alternator from overtemp.
 
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With the 750hp QSK19 engines the 180 didn't need it. The 175 has 450hp N14RE engines, so the Traction Boost was to give them some extra power if they lost an engine. Particulaly if they were running on 100mph sections. Don't think it has ever been used in anger though. If was thought that the transmission fitted to 175 couldn't cope with continuous 500hp, so that is why the engine was rated to 450hp.
 
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route:oxford

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Tynwald said:
With the 750hp QSK19 engines the 180 didn't need it. The 175 has 450hp N14RE engines, so the Traction Boost was to give them some extra power if they lost an engine. Particulaly if they were running on 100mph sections. Don't think it has ever been used in anger though. If was thought that the transmission fitted to 175 couldn't cope with continuous 500hp, so that is why the engine was rated to 450hp.
Click to expand...

Are the QSK19 engines in the 180 now of greater value than the unit itself?

In that they could be used in a new unit, as they were manufactured at a time when they were compliant.
 
anamyd

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I didn't know about the boost, but I can just imagine it helping the fires start :)
 
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sw1ller

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Tynwald said:
With the 750hp QSK19 engines the 180 didn't need it. The 175 has 450hp N14RE engines, so the Traction Boost was to give them some extra power if they lost an engine. Particulaly if they were running on 100mph sections. Don't think it has ever been used in anger though. If was thought that the transmission fitted to 175 couldn't cope with continuous 500hp, so that is why the engine was rated to 450hp.
Click to expand...

I used it on a cool day last summer. It works best on the 2 car units as a 3 car has enough power to crack on with an engine out. If the sun was out I wouldn’t have used it though. Did make a difference on the hills.
 
anamyd

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sw1ller said:
I used it on a cool day last summer. It works best on the 2 car units as a 3 car has enough power to crack on with an engine out. If the sun was out I wouldn’t have used it though. Did make a difference on the hills.
Click to expand...
and it didn't even catch fire...?
 
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OrangeJuice

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I think I've been on a few 175 trips down the Marches when the HVAC has cut out or powered down and someone mentioned it was to do with using all the power for 100mph running. So is this an automatic thing for high speeds or specifically when the driver selects it?
 
hexagon789

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Erniescooper said:
The 175 has a Traction Boost function that will re-rate the engine to 510 hp for 20 minutes at a time and will load shed the three phase functions of the HVACs by dropping out contractor TBST which will also drop out in the event of the alternator overheating. The 180 only the contactor TBST part of the circuit to protect the alternator from overtemp.
Click to expand...

Thank you for the explanation. How does the engine 'up-rate' though, does it rev higher or is it something else?

Additionally, am I correct that the Traction Boost is selected via Notch 4 and if so does that mean that generally 175s are driven on Notches 1-3?

Tynwald said:
With the 750hp QSK19 engines the 180 didn't need it. The 175 has 450hp N14RE engines, so the Traction Boost was to give them some extra power if they lost an engine. Particulaly if they were running on 100mph sections. Don't think it has ever been used in anger though. If was thought that the transmission fitted to 175 couldn't cope with continuous 500hp, so that is why the engine was rated to 450hp.
Click to expand...

I take it the function is isolated though?

anamyd said:
I didn't know about the boost, but I can just imagine it helping the fires start :)
Click to expand...

Firing up the jet propulsion? :lol:

OrangeJuice said:
I think I've been on a few 175 trips down the Marches when the HVAC has cut out or powered down and someone mentioned it was to do with using all the power for 100mph running. So is this an automatic thing for high speeds or specifically when the driver selects it?
Click to expand...

I had thought the function was isolated, perhaps not then.
 
Strat-tastic

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anamyd said:
what does this mean...? :p
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rebmcr said:
It's a reference to some technical systems (and associated rules) added to Formula 1 races, to try and add excitement.
Click to expand...

Yes, it's a button to increase power which can only be used for a limited time each lap, with the hope of helping you to overtake. And as for adding excitement, well, we're still waiting for that... :rolleyes: ;)
 
Erniescooper

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hexagon789 said:
Thank you for the explanation. How does the engine 'up-rate' though, does it rev higher or is it something else?

Additionally, am I correct that the Traction Boost is selected via Notch 4 and if so does that mean that generally 175s are driven on Notches 1-3?



I take it the function is isolated though?



Firing up the jet propulsion? :lol:



I had thought the function was isolated, perhaps not then.
Click to expand...
When you press the traction boost button there is an input to the engine ECM which activates a different map on the engine but I’m not sure which parameters are changed.
I’ve been away from 175 for about 12 months but it was still in use when I left but it was rarely used as without the air con running the saloon would heat up really quick and it wouldn’t be long before passengers complained.
 
hexagon789

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Erniescooper said:
When you press the traction boost button there is an input to the engine ECM which activates a different map on the engine but I’m not sure which parameters are changed.
I’ve been away from 175 for about 12 months but it was still in use when I left but it was rarely used as without the air con running the saloon would heat up really quick and it wouldn’t be long before passengers complained.
Click to expand...

Not ideal in the summer months!

So it's selected via a button rather than Notch 4 on the TBC?
 
Erniescooper

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anamyd said:
Once the boost has been used, how long does the driver have to wait until they can re-engage it...?
Click to expand...
He can press it straight away and as many times but I would imagine the limiting factor would be the melting passengers
 
185

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Is this anyone's prop-shaft that's just landed in my front driveway? :o

I mean, seriously... was on a 175 on the WCML last week at 96mph - it felt like it was coming apart.
 
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sw1ller

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hexagon789 said:
In that case - does Notch 4 actually do anything different to Notch 3?
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Yes, there’s a difference between 3 and 4. Nothing major, but It’s noticeable.

The button to engage the “boost” is on the far right isolation panel as has been said, it’s the blue one next to the front window if anyone’s playing train sim. You need a drivers key to “unlock” it. You can press it whenever you want (can just about reach it on the move but it’s not ideal) and you get 20 minutes from the last press.

I will state now though, that I was under the impression the 175’s normally run on 380hp and the button pumps it up to 450hp. The engines are 450hp so if I’m wrong, is the other 70hp supplied by KERS? (Sticking with the F1 theme). I can’t think how this would work with the engine.

I get that it takes electricity from 5 separate areas (basically the HVAC and the bogs) but how does it convert this electricity into HP into the engine?
 
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craigybagel

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OrangeJuice said:
I think I've been on a few 175 trips down the Marches when the HVAC has cut out or powered down and someone mentioned it was to do with using all the power for 100mph running.
Click to expand...

There is no 100mph running on the Marches - it's 90mph max. Wilmslow - Crewe is a good long run at 100mph, but you can't do the ton South of there until beyond Bridgend.

185 said:
Is this anyone's prop-shaft that's just landed in my front driveway? :o

I mean, seriously... was on a 175 on the WCML last week at 96mph - it felt like it was coming apart.
Click to expand...

That's the track itself. The aforementioned Wilmslow - Crewe run is as smooth as you like at 100mph. Or it might have been a dodgy unit you were on - if you were on one of the diverted Crewe - Warrington - Oxford road services, they easily attain 100mph and sustain it all the way to where the limit drops around Warrington, so long as nothing else gets in the way.
 
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craigybagel said:
There is no 100mph running on the Marches - it's 90mph max. Wilmslow - Crewe is a good long run at 100mph, but you can't do the ton South of there until beyond Bridgend.



That's the track itself. The aforementioned Wilmslow - Crewe run is as smooth as you like at 100mph. Or it might have been a dodgy unit you were on - if you were on one of the diverted Crewe - Warrington - Oxford road services, they easily attain 100mph and sustain it all the way to where the limit drops around Warrington, so long as nothing else gets in the way.
Click to expand...

Possibly a Sunday between wolves and Crewe via stafford. Can get a bit rickity. There was one unit running around with rather poor (but serviceable) suspension the other day and even I was glad to get off it.
 
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