Different engine revs on 66/67

[truckman060473]

when a 66 with freight comes up to a red signal the revs drop down to total idle making a quiet, frequent "phew phew phew" sort of whistle noise. when similarly engined 67's stop at stations with coach stock the revs stay high. what is the reason for this difference? I remember seeing a 67 on mail starting up at Swansea in 2000, which revved up to gain vacuum/air brakes but then dropped back to idle after a minute or so.

 

[royaloak]

possibly because when the loco is supplying ETS to the train the revs are held higher.

 

[truckman060473]

i was thinking it might be that, seeing as the freight would need much more braking power and so if the 66 drops to idle then the 67 on coaches would certainly drop to idle. is it auxiliary generators or something, required for the train heating that causes the huge 3000+hp engine to need to rev powerfully like this?

 

[royaloak]

You will probably find it is only about 100rpm more than normal idle.

 

[truckman060473]

what the range then? about 400 - 1000 is it? the 67's are quite loud then at around 500rpm. the virgin 57 i went on yesterday was remarkably quiet by comparison. the 57 on the Holyhead seems loud. perhaps because the high power ETS required for the on-board chefs' cookers!

 

[starrymarkb]

Best comparison is HST sets - The leading powercar will be at idle but the trailing will be revving as it supplies the coaches with power

 

[ailsa]

what the range then? about 400 - 1000 is it?

I seem to remember that 66s idle at 200rpm and 67s are 400rpm. The 67 needs the higher speed primarily for ETH but I am sure there are other reasons too.

Also 66s sometimes raise their idle speed for a couple of minutes before dropping down again, presumably to charge the batteries and build up air pressure.

 

[TDK]

i was thinking it might be that, seeing as the freight would need much more braking power and so if the 66 drops to idle then the 67 on coaches would certainly drop to idle. is it auxiliary generators or something, required for the train heating that causes the huge 3000+hp engine to need to rev powerfully like this?

It can be a number of thing that cause a 67 engine to rev above it's idle revs of 265 - 270rpm, what is being described here is the ETH or HEP as it is referred to on a 67, when ETH is active the revs of a 67 are about 490. The other things that can cause a 67 engine to rev is of course taking power, cold water temp, auxilliary power demand and the compressor. The ETH on a 67 will rev the engine the same as in power notch 3.

Depending on the other demands like cold water temp and compressor demand the revs will occasionally go to the equivelent of notch 2, about 320 rpm. It can be a bit disconcerting when uncoupling a loco or coupling if you are in between the loco and the coaches and the engine revs up
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what the range then? about 400 - 1000 is it? the 67's are quite loud then at around 500rpm. the virgin 57 i went on yesterday was remarkably quiet by comparison. the 57 on the Holyhead seems loud. perhaps because the high power ETS required for the on-board chefs' cookers!

The range is 267 rpm to 910 rpm in general

 

[kestrel]

You also have to take into account the 3 different types of silencers involved.
All 3 locomotive types (57/66/67) are fitted with essentially the same type of engine an EMD 2stroke V12 (66/67 slightly bigger bore and electronically controlled),
The 66 will be the quietest type in having the more efficient and larger silencer, the 67 was initially fitted with the same type but found to be too heavy hence the small one fitted and the deeper louder exhaust flux, class 57 on the Virgin leased stroke 3's, have a modified version of that fitted on the stoke 6's on FGW in that they have a single exhaust outlet as opposed to 2 when converted, this was done to produce a stronger exhaust flux to help clear the Air con vents on the pendo's (holyhead drags)

 

[TDK]

You also have to take into account the 3 different types of silencers involved.
All 3 locomotive types (57/66/67) are fitted with essentially the same type of engine an EMD 2stroke V12 (66/67 slightly bigger bore and electronically controlled),
The 66 will be the quietest type in having the more efficient and larger silencer, the 67 was initially fitted with the same type but found to be too heavy hence the small one fitted and the deeper louder exhaust flux, class 57 on the Virgin leased stroke 3's, have a modified version of that fitted on the stoke 6's on FGW in that they have a single exhaust outlet as opposed to 2 when converted, this was done to produce a stronger exhaust flux to help clear the Air con vents on the pendo's (holyhead drags)

The silencers will not have any effect on the rpm of the engine just the sound. The 66 is louder in the cab than a 67 probably due to sound proofing in the 67 is better.

 

[Drimnagh Road]

We've always referred to our 201s and your 66s as "Nee Nees" due to the sound they make when idle.

 

[gregh]

Turbo cool-down will also keep engine revs high for anything up to 20 minutes after a loco has come to a stand, especially if they have been working hard in the period immediately before coming to a stand.

 

[kestrel]

The silencers will not have any effect on the rpm of the engine just the sound. The 66 is louder in the cab than a 67 probably due to sound proofing in the 67 is better.

I'm well aware of that i'm not a kiddie, if you read a couple of posts up you'll see a post about the noise ;o)

 

[TDK]

I'm well aware of that i'm not a kiddie, if you read a couple of posts up you'll see a post about the noise ;o)

Hi there, Just going by the thread title

 

[Wyvern]

We've always referred to our 201s and your 66s as "Nee Nees" due to the sound they make when idle.

Ying-ying?

 

[royaloak]

I have some other names for them, but I had better keep them too myself!

 

[kestrel]

Hi there, Just going by the thread title

lol no probs chap