Class 172 Chiltern, how come so quiet compared to class 165

[pethadine82]

How come these are engineered so that they are much quieter compared to a 165. It sounds as though you are in a coach / bus rather than a train, and you can hear the engine moving up the gears.

 

[jonty14]

I think the 172s have a different type of bogie. Like the Voyagers. I might be totally wrong though!!

 

[D365]

I think the 172s have a different type of bogie. Like the Voyagers. I might be totally wrong though!!

Classes 172, 220 and 222 use a FLEXX Eco bogie - the same as will be fitted to the London Aventra fleets.

 

[Harbon 1]

The 172s are newer and a different design/family of units at a guess.

The 172s also have mechanical transmission rather than (I assume) hydraulic on the Networkers.

 

[Mikey C]

Newer generation of engines as well, the turbos are from the 1990s and diesel engine technology has moved on significantly since then (not always successfully as VW have found!)

 

[Philip Phlopp]

Classes 172, 220 and 222 use a FLEXX Eco bogie - the same as will be fitted to the London Aventra fleets.

The legendary, nay mythical British Rail Advanced Suburban Bogie, as was. The rights to it, the P3/T3 bogies (found under Electrostar/Turbostars) and the underused P4/T4 bogie (Class 158 and Mark 3 DVT) which should have been a 140mph capable DMU/EMU and coach bogie, all went with BREL when they were privatised.

It suits the Turbostar (which started life as the Networker, anyway) because that's what it was designed for. It'll do brilliantly under the Aventra, I'm sure, and unlike Siemens SF7000, the option exists for their inside framed bogies to have disc braking on the powered wheelsets, not just the unpowered ones.

 

[Cherry_Picker]

Different transmissions too. A 165 has a fluid coupling while a 172 has a mechanically coupled automatic gearbox.

 

[D365]

It'll do brilliantly under the Aventra, I'm sure, and unlike Siemens SF7000, the option exists for their inside framed bogies to have disc braking on the powered wheelsets, not just the unpowered ones.

At least the tread brakes will make 'mulch' work of leaf fall season

 

[Peter Sarf]

As older engines and exhausts make more noise as they get worn out I expect that the 172s might catch up with the 165s anyway..

 

[edwin_m]

Different transmissions too. A 165 has a fluid coupling while a 172 has a mechanically coupled automatic gearbox.

Yes. The Sprinters tend to move off with the engines going flat out, with about 99% of the energy being wasted as heat in the hydraulic transmission. I presume a 172 starts at lower revs, and this was part of the reason to change from hydraulic to mechanical.

 

[Mikey C]

Yes. The Sprinters tend to move off with the engines going flat out, with about 99% of the energy being wasted as heat in the hydraulic transmission. I presume a 172 starts at lower revs, and this was part of the reason to change from hydraulic to mechanical.

They certainly sound very different from previous diesels, when it seems the engine has to be really flogged to get the train to move!

The 172s to me sound like a modern car or bus, taking off with quite low revs. I'm sure the residents along the GOBLIN line have really noticed the difference