Class 334 banging noise

[Eng1Alpha]

Hi
I am a daily user of Scotrail's 334 train and on a recent journey there was a loud banging noise from the underside of the train. Almost like someone was striking the underside with a metal pole. It happened at various times. Braking-accelerating-idle.
It was loud enough other passengers were startled each time it 'pinged'. The best description is similar to a cat spring when it snaps.

Just curious, but any info welcome.
--- old post above --- --- new post below ---
Car Spring! Oops.

 

[Peter Mugridge]

Was it definitely from the underside?

My first thought is it's the vacuum circuit breakers operating on either side of a neutral section, but I would expect the noise from those to be from the roof area.

 

[ExRes]

Could it have been some Remainers hanging onto the underside of the train while trying to sneak into Free Scotland from England?

 

[PaxVobiscum]

Was it definitely from the underside?

Candidates for the Metre High Club in the toilet?

 

[Eng1Alpha]

Hi,

Yes definitely underside. It was directly beneath our feet. I thought maybe a loose brake pipe. But it was a very loud deafening ping.

 

[Harbornite]

Candidates for the Metre High Club in the toilet?

 

[Lrd]

Compressor?

 

[deltic1989]

Couldn't be a wheel flat could it?

 

[61653 HTAFC]

Couldn't be a wheel flat could it?

wouldn't the noise of a wheel flat be a constant, rhythmic one (at a steady speed) and increasing/decreasing with acceleration/deceleration?

 

[NotATrainspott]

It's not a compressor. It's almost as if there's hard parts of the body and bogies which are sometimes coming into contact.

 

[PaxVobiscum]

It's not a compressor. It's almost as if there's hard parts of the body and bogies which are sometimes coming into contact.

 

[bengley]

Most likely a knackered bush or something on the suspension - not dangerous but definitely something which should be fixed sooner rather than later.

 

[Eng1Alpha]

I think bengley is probably spot on.

 

[318259]

They've always done that from time to time. It's not just a noise, you can actually feel an impact through the floor.

I always thought it was either the suspension or something like a loose stone or Irn Bru bottle being flung up from the tracks and hitting the underside of the train.

 

[Tynwald]

Anti-roll bar bushes a regular one.

 

[No Fault Found]

Anti-roll bar bushes a regular one.

This^^^

Failing that, damper bushes, bump stops making contact due to incorrect vehicle heights,traction centre bush worn, just about any part of the underframe mountings loose / bushes worn.