MLV class 419

[roythebus1]

Agreed, but don't forget it is quite possible to get far higher speeds in parallel. I've only trained on MLVs during my SR driver training course but have worked on the converted 501 motor cars that ran on battery power on the ECML.

 

We had to collect a pair of them from Hertford North one day, me 2nd manning. They too were limited to 25 mph so the sign in the cab said. But we got put out behind an all stops 313. We have hime a bit of a start and on downhill sections easily reached 45mph or more. We followed on single yellow all the way to Bounds Green at that sort of speed, but then it's downhill most of the way. I know they're a different beast to the MLV battery wise as they are full of batteries. They'd also last 12 hours or more when we used them down to Moorgate when that was being converted. The traction equipment is similar to that of the MLV so there's no reason to expect a decent MLV not to do Redhill-Tonbridge. They will go as fast as the balancing speed of the motors allows them to go.

 

It's all down to the driver's route knowledge and the use of gravity. Also remember he doesn't need to take power all the time. Get to 25, shut off, coast...drop to 20, take power, 25, shut off, coast...

 

[HGR]

In an MLV the traction battery is 176 V (200 V on charge), so about one quarter of the normal line voltage. The express gear ratio is intended to balance out at roughly 90 MPH on the level at rated load on 750 V in weak field. The speeds I listed 'on battery' are in parallel but you only have the much lower voltage of the battery so won't reach any significant speeds unless going downhill.

 

The batteries in the ex. 501 battery locos were connected for 320 V operation. These had different motors which were rated for 630 V. The Watford DC lines were in effect LT lines, so a bit lower voltage than B.R. Southern third rail. Hence the motors can reach a higher speed than an MLV on battery. On the Watford DC lines the 501s were quoted as 70 MPH because of their really low gear ratio, but I think towards the end they were restricted to 60 MPH ? Getting the likes of 45 MPH at roughly half voltage on level to falling gradient would be reasonably expected.

 

The amount of batteries, hence the capacity available, determines the running time. With the battery locos it also resulted in them being a rather hefty RA 4 as they ended up being not far short of 60 Tons each. One of the reasons for the 25 MPH limit was this increased weight compared to the available brake force. 

 

When on battery there is not much advantage of cycling between motoring and coasting, unless you are coasting in preparation to slow down for a speed restriction or a stop. The extra current drawn in periodically accelerating back up say from 20 to 25 MPH and saved whilst coasting in between averages out about the same as the steady current that obtains motoring at the same average speed. 

 

 

 

 

[Wickham Green too]

8 minutes ago, HGR said:

......... When on battery there is not much advantage of cycling between motoring and coasting, ........

Regeneration would have been nice to have ...... but ................................

[class37418stag]

Hello 

class 419 MLV running slow for 20 miles without third line and arrive at start third line and pick electric lives for charge up to battery ?

[roythebus1]

Yes, once it goes back on the third rail the motor generator will run and charge the battery.

 

[roythebus1]

As a bit of an aside from the OP, when I learnt the Portsmouth direct (via Haslemere), one of the old boys told me when you leave Haslemere on the Up, get to about 40 by the over bridge, shut off and the train will coast to Guildford. I tried it one day with an 8 car CEP/VEP or whatever. And I got to just over 40 by the over bridge and shut off. The train accelerated to just over 90 on the downhill bit through Milford, I had to brake a bit for Godalming and Farncombe, then it carried on up to 70 , entering Guildford tunnel still doing 55, and I had to use the brake to stop at Guildford.

 

I doubt if the old Nelson stock would have rolled that far as it didn't have the benefit of roller bearings.