Bumping and jerking HST

[Journeyman]

It is like nails down a chalkboard to me. I have often wondered why folk who complain about the noise of underfloor engines often find this one of the MK3's charming idiosyncrasies or similarly will get all excited about the hell fire thrash being generated by loco.

Absolutely - I regularly travel on 170s, and they're only particularly noisy when accelerating hard. Even then, the noise is fairly constant in pitch and volume and very easy to tune out. The noise of the gangway squeal is exactly as you say - a noise that's extremely irritating in pitch, and the random element of it makes it really noticeable. Honestly, we can do a lot better than that these days - the Mark 3 really isn't the luxurious palace the fanboys regularly make out.

 

[HaggisBotherer]

It is like nails down a chalkboard to me. I have often wondered why folk who complain about the noise of underfloor engines often find this one of the MK3's charming idiosyncrasies or similarly will get all excited about the hell fire thrash being generated by loco.

Rest assured I am not complaining about the noise of underfloor engines, nor do I have any understanding of any train spotter who bangs on about 'thrash' and 'clag' or who lives their life according to the maxim of "my favourite class is better than your favourite class, so ner". The very concept of someone being a 'fanboy' of a type of carriage nearly produced a tea/screen interface moment when I read the previous post. There are a lot of odd people out there.

I was merely commenting that the gangway screeching is a characteristic noise of Mk3s and, as such, is something whose passing I will notice and will, in a way, miss. In the same way that I rather miss semaphore signalling, goods yards, shunting, roaring fires in waiting rooms in winter and Val, John 'n' Pete on Blue Peter Nostalgia, that's all!

 

[bastien]

Absolutely - I regularly travel on 170s, and they're only particularly noisy when accelerating hard. Even then, the noise is fairly constant in pitch and volume and very easy to tune out. The noise of the gangway squeal is exactly as you say - a noise that's extremely irritating in pitch, and the random element of it makes it really noticeable. Honestly, we can do a lot better than that these days - the Mark 3 really isn't the luxurious palace the fanboys regularly make out.

There's some piece of rotating machinery under the HST coach that makes at least as much noise as the 800's diesels! I'm not sure what it is, but it seems to 'rev up' as the train accelerates, the air-con compressor perhaps?

 

[TractiveEffort]

There's some piece of rotating machinery under the HST coach that makes at least as much noise as the 800's diesels! I'm not sure what it is, but it seems to 'rev up' as the train accelerates, the air-con compressor perhaps?

Air con compressor it certainly is and the same as any of the 3 phase equipment connected directly to the train supply, it will run better and faster as the driver goes up through the notches - voltage increase from approx 270v in N2 to 415v in N5.

 

[TractiveEffort]

There are quite a few LNER powercars running around with traction motors isolated at the moment, so this may have an effect on the ride quality, i.e. if the front powercar has 2 out of 4 motors isolated then the rear powercar is more powerful, and will cause the feeling of getting shoved from behind, a bit like when the class 91 is pushing a MK4 set towards London, however with the Mk4 this is cushioned by the device above the coupling, I forget the proper technical term maybe its a dampner or something.
With the HST's though there is nothing to cushion it when the rear power car is doing more work than the front which causes it to be more jerky and violent

In low adhesion conditions, having two traction motors on the front power car isolated will be an advantage and will reduce the amount of bumping and jerking, as isolating 2 traction motors automatically reduces the available power in that power car to N3. The rear power car will in nearly every situation, slip less, so whilst it will be pushing, the leading power car will be lagging, so there will be no bumping or jerking as the buck eyes will all be pushed up together.

 

[43096]

In low adhesion conditions, having two traction motors on the front power car isolated will be an advantage and will reduce the amount of bumping and jerking, as isolating 2 traction motors automatically reduces the available power in that power car to N3. The rear power car will in nearly every situation, slip less, so whilst it will be pushing, the leading power car will be lagging, so there will be no bumping or jerking as the buck eyes will all be pushed up together.

But at the cost of lost time, especially with LNER’s 9 car sets. In any case the bumping and jerking in low adhesion conditions is nothing like as bad as it used to be with those power cars fitted with the Brush electronics upgrade which included new wheel slip/slide control systems.

 

[TractiveEffort]

But at the cost of lost time, especially with LNER’s 9 car sets. In any case the bumping and jerking in low adhesion conditions is nothing like as bad as it used to be with those power cars fitted with the Brush electronics upgrade which included new wheel slip/slide control systems.

The Brush upgrade certainly copes with wheelslip better than the original fitted equipment, indeed instead of notching off and trying cope with the slip by Driver intervention (and some are better at it than others) the Brush upgrades just say keep the power handle in the notch you want and let the system sort it out.

 

[43096]

The Brush upgrade certainly copes with wheelslip better than the original fitted equipment, indeed instead of notching off and trying cope with the slip by Driver intervention (and some are better at it than others) the Brush upgrades just say keep the power handle in the notch you want and let the system sort it out.

The system is always going to be able to react faster than any driver can.

Bizarrely neither GWR nor ScotRail have gone for the upgrade, despite the big cost savings from extended bogie life as a result.

 

[TractiveEffort]

The system is always going to be able to react faster than any driver can.

Bizarrely neither GWR nor ScotRail have gone for the upgrade, despite the big cost savings from extended bogie life as a result.

GWR have two powercars with the Brush system (or did, I don’t know if they have gone off lease now) and they were by far the two most reliable power cars in the fleet.

 

[43096]

GWR have two powercars with the Brush system (or did, I don’t know if they have gone off lease now) and they were by far the two most reliable power cars in the fleet.

They still have - 43053/056. Both got the new electronics before they transferred to FGW (as it was then); they were fitted back when they were with Midland Mainline.

 

[DPWH]

The hum of underfloor engines is rather dull, boring and annoying.

The screeching and lurching of gangways is characterful.

 

[gimmea50anyday]

There are quite a few LNER powercars running around with traction motors isolated at the moment, so this may have an effect on the ride quality, i.e. if the front powercar has 2 out of 4 motors isolated then the rear powercar is more powerful, and will cause the feeling of getting shoved from behind, a bit like when the class 91 is pushing a MK4 set towards London, however with the Mk4 this is cushioned by the device above the coupling, I forget the proper technical term maybe its a dampner or something.

Think it's called a Pullman Buffer or a Pullman buffing plate. It's essentially a buffer lined up with the base of the corridor connection of the adjoining coach.

 

[Journeyman]

The hum of underfloor engines is rather dull, boring and annoying.

The screeching and lurching of gangways is characterful.

You have got to be kidding me.

 

[K.o.R]

We were sat in the very first set of seats in the very first (well, last) coach from KX to Edinburgh a few months back and my goodness it was a bumpy ride. Still, endless free drinks and snacks made up for it

 

[Journeyman]

We were sat in the very first set of seats in the very first (well, last) coach from KX to Edinburgh a few months back and my goodness it was a bumpy ride. Still, endless free drinks and snacks made up for it

I enjoyed the free drinks, agreed, but it was frustrating that half the liquid ended up on the table, with some of it reaching my lap, every time another train passed us.