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Post by Deleted on Mar 3, 2011 22:04:07 GMT
Whilst watching old East London line videos on Youtube and the Baker Street - Rickmansworth cab ride video (shot in 1992) also on Youtube. I couldnt help noticing how much more of a 67ts style whining sound they had when pulling away and also they seem to have accelerated quicker  |
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SE13
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RIP 23-Oct-2013
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Post by SE13 on Mar 3, 2011 22:16:16 GMT
Well, I'm fairly sure that the stock worked between the lines, but it also got me thinking that any time I used ELL (which was admittedly VERY rare) I seem to remember a different seat cover moquette...
In view of both points raised, I'll leave this thread here, and move it to the relevant area depending on the answers.
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Post by Deleted on Mar 3, 2011 22:31:55 GMT
That's probably pre-refurb SE13! The units were regularly mixed at Neasden, where most work had to be undertaken, AIUI.
On the cab ride, can you see the weak field up?
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Post by Deleted on Mar 3, 2011 23:02:58 GMT
No but its deffo over 30mph
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Post by Deleted on Mar 4, 2011 10:47:10 GMT
On the old East London line was there anywhere where A Stock could do more than 30?
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Post by Deleted on Mar 4, 2011 10:48:28 GMT
You could most certainly do >30mph with the weak field down, the A stock goes for higher speeds than the Ds and Cs.
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metman
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Post by metman on Mar 4, 2011 17:02:59 GMT
They did seem to have a different noise in the old days not the mature hum they have now. I'm sure they refurbed the motors too, maybe played about with the windings? I'm not that great with motors, all I know is they are still LT114s.  |
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Post by Deleted on Mar 4, 2011 18:22:58 GMT
Wernt LT114's in the 59 and 62ts aswell?
Also, why does everyone say that weak field limits the speed to 30mph but makes it accelerate faster?
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Post by Deleted on Mar 4, 2011 19:34:53 GMT
Weak field increases top speed and acceleration but there is less torque. I'm just trying to figure out if the line speeds on the former east London line exceeded 30 mph.
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Post by Deleted on Mar 4, 2011 19:59:00 GMT
BVE Has some 40mph parts
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metman
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Post by metman on Mar 5, 2011 10:20:49 GMT
The 59/62ts had LT112s I think.
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Post by 100andthirty on Mar 5, 2011 12:52:56 GMT
Weak field increases top speed and acceleration but there is less torque. I'm just trying to figure out if the line speeds on the former east London line exceeded 30 mph. Weak field on its own increases the current flowing in the motors and therefore torque increases! Weak field only cuts in usually when the train has finished notching though the sequence of starting resistors. A stock, though had a special feature to help it cope with a barely adequate electrical power system north of Finchley Road. Flag switch up on A stock allowed the increased torque to deliver the higher speed but also set the acceleration to rate 1. A stock has two rates - 1 (low) and 2 (higher). On older trains rate 1 was intended for silppery conditions. |
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Post by Deleted on Mar 5, 2011 19:28:03 GMT
Going off topic here but, is rate 1 or 2 optional even with the flag up?
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Post by Deleted on Mar 6, 2011 1:35:15 GMT
Weak field increases top speed and acceleration but there is less torque. I'm just trying to figure out if the line speeds on the former east London line exceeded 30 mph. Weak field on its own increases the current flowing in the motors and therefore torque increases! Weak field only cuts in usually when the train has finished notching though the sequence of starting resistors. This from Wikipedia : Wound field DC motor The permanent magnets on the outside (stator) of a DC motor may be replaced by electromagnets. By varying the field current it is possible to alter the speed/torque ratio of the motor. Typically the field winding will be placed in series (series wound) with the armature winding to get a high torque low speed motor, in parallel (shunt wound) with the armature to get a high speed low torque motor, or to have a winding partly in parallel, and partly in series (compound wound) for a balance that gives steady speed over a range of loads. Further reductions in field current are possible to gain even higher speed but correspondingly lower torque, called "weak field" operation. |
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Post by 100andthirty on Mar 6, 2011 7:51:27 GMT
The Wikipaedia entry is simplistic. The motors have to deliver more power if they are to propel the train at a higher speed.
Say, that the the train is running on level track and is running at 40mph on "full power". It's running at constant speed with the flag switch down. This is called the balancing speed. The power produced by the motor exactly balances the train's resistance to motion.
Then the second man in the cab, say, raises the flag switch. The train will accelerate. In order to accelerate, it has to produce more torque. As speed rises, torque will fall until the torques which delivers the force at the running rail is equal to the higher resistance to motion at the higher speed.
I hope this explains things.
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