When did "docking" get changed to "pitching"?
Well, those notices have been there for years, so no idea!
When did "docking" get changed to "pitching"?
47s had a reputation for rolling like a ship in a force 12 at 95mph
Many of the modern units suffer from 'lurching' on rougher track and over points and crossings. .../QUOTE]
I've noticed that although not all trains do badly. The notorious Mill Hill bumps on the MML fasts would be quite rough when in a 319. When the Electrostars arrived, although smoother, they really did lurch at some of the bumps, - even the brand new 387s behaved that way. The 700s though seem to ride them a lot better, even though they take them at 100mph linespeed.
I believe DLR wheel profile is more like heavy rail than trams, which isn't optimum for tight curves. The hunting is probably indeed caused by having bogies that are easy to turn to take those curves, and therefore don't damp out that type of oscillation.Possibly a bit like trams, the profile is designed more for tight curves than fast running as you surmise.
Certainly most trams tend to get a bit of a tail wag going when they get to their 70-80km/h ceiling.
The Class 458 fleet had its yaw dampers removed when it was regeared for 75mph.Incidentally vehicles passed for more than 75mph require extra yaw dampers between bogie and body, which are quite obvious when you
look for them. A good example being the Turbo fleets- 165/0 do not have them whereas 165/1 do, despite having otherwise identical bogies.
The Class 458 fleet had its yaw dampers removed when it was regeared for 75mph.
The big exception to this is the BT10 bogie, which doesn’t need and doesn’t have a yaw damper.
Maintenance reduction, I believe. If you don’t need them, why keep them?Interesting. Why remove them? To save on maintenance, or does it reduce track wear somehow?
That is very arguable. 45 years in service says otherwise.Arguably it does need them (or something else) - the Mk3 coach has a very characteristic side to side sway which shows inadequate damping.
Interesting. Why remove them? To save on maintenance, or does it reduce track wear somehow?
That is very arguable. 45 years in service says otherwise.
BT10s are not an awful ride, though. Quite the opposite in fact. Your view is something of an exception to the norm - there are far more of the view that the BT10 remains unsurpassed in terms of ride quality.Pacers have been in service for a while as well, and they have always had an awful ride
BT10s are not an awful ride, though. Quite the opposite in fact. Your view is something of an exception to the norm - there are far more of the view that the BT10 remains unsurpassed in terms of ride quality.
I wouldn't say the Mk3 had an awful ride (the Mk4 can have that "accolade"), but to suggest they are unsurpassed is unfair to trains with a genuinely excellent ride such as the Class 158 and the heavyweight Class 221.
I believe DLR wheel profile is more like heavy rail than trams, which isn't optimum for tight curves. The hunting is probably indeed caused by having bogies that are easy to turn to take those curves, and therefore don't damp out that type of oscillation.
I wouldn't say the Mk3 had an awful ride (the Mk4 can have that "accolade"), but to suggest they are unsurpassed is unfair to trains with a genuinely excellent ride such as the Class 158 and the heavyweight Class 221.
The big exception to this is the BT10 bogie, which doesn’t need and doesn’t have a yaw damper.
The BT10 bogie does need and does have a yaw damper, except that it's not obvious. It used the same principle as that also used in some earlier bogies such as the B4 being a large disc of friction material, essentially brake lining, surrounding the centre location pin. It's protected from the elements and so offers consistent friction values.The Class 458 fleet had its yaw dampers removed when it was regeared for 75mph.
The big exception to this is the BT10 bogie, which doesn’t need and doesn’t have a yaw damper.
Of course the 158 has a better ride than the BT10/Mark 3 combination. It used BR's next iteration of bogie design after the BT10 and the Series 3 bogie now used in its thousands under the PEP derived vehicles, Networkers, Electrostars and Turbostars. It used all the experience from these coupled to a very stiff body formed of welded aluminium extrusions.I wouldn't say the Mk3 had an awful ride (the Mk4 can have that "accolade"), but to suggest they are unsurpassed is unfair to trains with a genuinely excellent ride such as the Class 158 and the heavyweight Class 221.
The BT10 bogie does need and does have a yaw damper, except that it's not obvious. It used the same principle as that also used in some earlier bogies such as the B4 being a large disc of friction material, essentially brake lining, surrounding the centre location pin. It's protected from the elements and so offers consistent friction values.
Of course the 158 has a better ride than the BT10/Mark 3 combination. It used BR's next iteration of bogie design after the BT10 and the Series 3 bogie now used in its thousands under the PEP derived vehicles, Networkers, Electrostars and Turbostars. It used all the experience from these coupled to a very stiff body formed of welded aluminium extrusions.
It's a pity the Series 4 wasn't more widely used but apparently the position regarding the ownership of the intellectual rights got very confused at the time of the various BREL/ABB takeovers and the dismemberment of BR's design offices.
Glad it's not just me who thought that about 387 ride quality. Very easy comparison to do on the same track out of Paddington.I think the best riding bogie is definitely the one fitted to the 165s and 166s. Absorbs bumps very well and very little sideways motion.
Just a pity that it was ruined by bombardier as the 387s have some very violent sideways jolts, ruining the ride quality.
It's a shame that in its 18 year product life, Bombardier didn't get around to correcting a flawed bogie setup on the Electrostars, -I would have thought that the availability of the 110mph versions would have triggered that.Glad it's not just me who thought that about 387 ride quality. Very easy comparison to do on the same track out of Paddington.
Glad it's not just me who thought that about 387 ride quality. Very easy comparison to do on the same track out of Paddington.
The basic bogie, as I wrote in post 18, is the same in both designs of vehicle, it is BR's Series 3.I think the best riding bogie is definitely the one fitted to the 165s and 166s. Absorbs bumps very well and very little sideways motion.
Just a pity that it was ruined by bombardier as the 387s have some very violent sideways jolts, ruining the ride quality.
That's true but many of the posts here are comparisons between different classes running over the same track. A good suspension system should give reasonable performance over all likely track 'imperfections'.A companion to ride quality is the state of the track that the stock has to deal with. BR had a large fleet of Tampers and the target for each midweek night shift was 80 chains of tamping.
NR have a fleet which is less than half in size and the target per midweek night shift is 40 chains.
It's a shame that in its 18 year product life, Bombardier didn't get around to correcting a flawed bogie setup on the Electrostars, -I would have thought that the availability of the 110mph versions would have triggered that.
I don't think the seating has anything to do with the trains ride. Stock that doesn't handle track irregularities well suffers more maintenance issues. The lateral lurches of the Electrostars affect standing passengers even more than those who are seated.... I think same as with previous comments about seating.... the people involved just dont care enough about passenger comfort.
I remember the comments other staff when the 377s were first tested about how bad the ride was (between brighton and seaford).
I don't think the seating has anything to do with the trains ride. Stock that doesn't handle track irregularities well suffers more maintenance issues. The lateral lurches of the Electrostars affect standing passengers even more than those who are seated.