Clicks on 1972 and C stock

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150001

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I rode on the 1972 and C stock this weekend and on these stocks, whilst accelerating, you can hear clicks (several of them) and with these come jerks causing you to be pushed back when standing up. What are these clicks and jerks; is it just a sign of age as I don't notice the new stock doing this. Also I've never been on a Class 455 and do they have this jerkiness at first?
 
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tom1649

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The lovely clicking or ticking sound you can hear on these older trains as they accelerate is a result of the (PCM) Pneumatic Camshaft Motor.

They have always done it from new.

I don't know the technical ins and outs of the system, but I'm sure someone else can explain.
 

John Webb

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The camshaft control system operates switches that alter resistances in series with the traction motors to control the speed and acceleration of the train. Modern traction uses entirely electronic means of motor speed control which eliminate both the noises and the surges of power of the older system.
Regards,
John Webb
 

tom1649

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All these electronics have taken a lot of the character out of modern trains unfortunately. This is all very well for your average passenger who likes a smooth ride, but as an enthusiast I like to hear the train 'working'.
 

150001

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Thanks! Must say that I love the ticking but do the 455s with SWT do it as well?
 

MCR247

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I remember hearing it on the stocks mentioned above but not 455s?
 

150001

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I just thought because the 455s are older EMUs they may clicking too.
 

Dstock7080

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Certainly cl.313 and cl.455 have a type of rotary accelerator, causing similar notching to LU Stock.
 

317666

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The 455s do have that sort of equipment and are a bit jolty when accelerating although it's harder to notice than on Underground Stock or 313s/507s/508s.
 

12CSVT

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The lovely clicking or ticking sound you can hear on these older trains as they accelerate is a result of the (PCM) Pneumatic Camshaft Motor.

They have always done it from new.

I don't know the technical ins and outs of the system, but I'm sure someone else can explain.

I seem to remember the Central line 1962 stock doing this as well.
 
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