Class 172 ZF gearbox - better or worse?

[73001]

Hi all, I've tried searching threads but haven't found anything on whether the Class 172 is more or less reliable and economical than the standard hydraulic transmission DMUs. They certainly seem quieter when setting off but are we likely to see anything similar produced in the future, given that there seems to be a few new DMU orders on the horizon. Are they any better/worse from a drivers point of view as well?

 

[RPM]

I don't sign 172s myself, but talking to colleagues who do, the view is that they are great for quick acceleration but very poor at coasting. The fact that they have to be kept under power most of the time must presumably have an effect on fuel efficiency - the Chiltern 172s have not been fitted with DAS for this reason.

 

[t_star2001uk]

The gearbox takes 7 seconds before you do anything:

7 seconds to engage direction.
7 seconds to return to neutral
7 seconds to re-engage direction

when stopping at a station with a short dwell time it seems better to leave it in drive, otherwise 14 seconds have elapsed before you can move again. They may be very good on acceleration but the gear change seems shocking and low speed control is abysmal.

 

[Philip Phlopp]

Hi all, I've tried searching threads but haven't found anything on whether the Class 172 is more or less reliable and economical than the standard hydraulic transmission DMUs. They certainly seem quieter when setting off but are we likely to see anything similar produced in the future, given that there seems to be a few new DMU orders on the horizon. Are they any better/worse from a drivers point of view as well?

They're not directly comparable unfortunately - they're fitted with different engines (which are more powerful) and the bogies give them a significant weight advantage (much lighter).

If it's the CAF bid that won (has it been confirmed yet ?) then it's likely to be a version of the NIR Class 4000, which has the same engine and transmission as the Class 172s, and as a result, they might even manage a BSI coupler and Class 158 and Class 170 compatibility. Bodyshell wise, they're pretty much a diesel version of Class 332/333 with a new cab design.

 

[TH172341]

From a passenger view they are pretty good - the first gear change at times can be a bit jerky if low power is applied, and moving off slowly (e.g out of Snow Hill) - if higher power is applied it's smoother and certainly don't notice after that first gear change really. Can jerk though if power is cut out just as the gearbox goes to change up a gear. Only other thing is wheelslip perhaps on wet rails - rode 172339 the other week in wet, damp conditions and driver cut the power off after starting off one of the times, and reapplied it, perhaps to avoid wheelslip - only assuming though.

Other than that find they're fine - the engines are quiet and the gearbox probably puts less strain on the engine with the flexibility in gears. As I say 90% of the time they're smooth; just if moving at a low low speed it can be more tempermental to control. Daresay the drivers though have grown to learn how they work now and learnt the 'style' - bit like adjusting to a new car I suppose.

I do know someone who drives them at LM and finds them great.

 

[73001]

That's very informative, thanks for the replies. I've never tried one but as I'm in Northernland I'd hope we got something similar in the new franchise. They sound so much better than the screaming pacer and sprinter engines we have here.
I used to work with ZF automatics in the past, with a decent engine and regular servicing the engines and gearboxes would last forever.

 

[TH172341]

No problem 73001 - A 172 design would be perfect right now for Northern - the flexibility of joining up units and the improved comfort provided. Hopefully the Aventra could be offered with something very similar, or CAF as well.

They've been good down here in the West Midlands - well built trains and done a good job in replacing the hard working 150s. They're ideal replacements for medium distance and short distance stock - the Snow Hill lines they run have quite a variety of sections - higher speed sections with fewer stops, and sections of multiple stops in close proximity. They've fitted that role very well and hopefully the cause of the two fires recently can be isolated and resolved.

Always liked ZF - both in buses and trains - perform well and as you say can go on for years with good maintenance.

 

[fgwrich]

Speaking of the ZF Gearboxes - a good comparison would be between a standard 158, The two modified with the ZF gearbox (@SWT & ATW) and a 172 to see if the difference in savings really is comparable.

172s can be ok, my only issues have been already mentioned about the occasionally snatchy gearbox.

 

[craigybagel]

Speaking of the ZF Gearboxes - a good comparison would be between a standard 158, The two modified with the ZF gearbox (@SWT & ATW) and a 172 to see if the difference in savings really is comparable.

172s can be ok, my only issues have been already mentioned about the occasionally snatchy gearbox.

ATW's unit (158834 incidentally) is fitted with a 4 speed Voith DIWA, not the 6 speed ZF in the 172s. I've only worked it once since it had the new transmission in but it definitely gets going lot quicker than a normal 158!

 

[168lover]

The chiltern ones seem quite nippy and i think faster accelerating than a 168?

 

[TH172341]

They probably are - the gear setup and lighter weight of the 172 (each carriage is approx 3 tonnes lighter than a 168 carriage) would contribute towards that.

 

[MCR247]

They probably are - the gear setup and lighter weight of the 172 (each carriage is approx 3 tonnes lighter than a 168 carriage) would contribute towards that.

And the fact that 'first generation' turbostars aren't known for their great acceleration

 

[Mikey C]

I was impressed with the LO Class 172s, operating a Metro service with regular stops. Much quieter (inside) than previous Turbostars without the high revving needed to get away from platforms of the 168s/170s.

 

[notadriver]

I've read that 172s are more economical than their less power 168/170 cousins. They are also faster climbing the Lickey than those units.

The inability to freewheel is interesting. I was told this by my Lorol colleagues. They needed to power downhills just to maintain speed.

It's a shame they jerk at low speeds at low power settings. I recently drove new ZF fitted coach which didn't do that. Perhaps it's because the box is set up for performance in the 172.

 

[superkev]

Hydraulic transmissions are simpler than mechanica ones but use more fuel. I seem to remember the two set 159's use around 10% and with 6 rather than ratios are presumably a bit quicker off the mark.
K

 

[TH172341]

And the fact that 'first generation' turbostars aren't known for their great acceleration

Haha - I missed the obvious

Yeah they don't really freewheel - noticed a bit of a difference between the 150s and 172s at first with that. The low speed thing isn't always - just occasionally the gear change can jerk a bit around if the power is cut off at that moment or low power applied. Never been uncomfortable I've found fortunately. As I said I know someone driving them and finds them great.

One day wouldn't mind trying the CAF4000s in Northern Ireland - when watching videos of them, notice a bit of a difference with the gear changes - 1st gear change sounds smoother, and none of the metallic rattles (is it the metal bin covers?) the 172s sometimes do at times around that 1st change.

 

[CP165]

One day wouldn't mind trying the CAF4000s in Northern Ireland - when watching videos of them, notice a bit of a difference with the gear changes - 1st gear change sounds smoother, and none of the metallic rattles (is it the metal bin covers?) the 172s sometimes do at times around that 1st change.

The NIR CAF4000s are nice units, they ride nicely and don't jerk around at all. Though there is a short amount of vibration as they start to move off.

 

[craigybagel]

I wonder if the rattles on the 172s is more down to Bombardier build quality, or company maintenance? Some of the 170s, CrossCountry's especially seem to rattle something terrible in a way the contemporary 175s never do.

 

[380101]

The NIR CAF4000s are nice units, they ride nicely and don't jerk around at all. Though there is a short amount of vibration as they start to move off.

The wider track gauge in NI/ROI adds to the nicer, smoother ride.

 

[TH172341]

The NIR CAF4000s are nice units, they ride nicely and don't jerk around at all. Though there is a short amount of vibration as they start to move off.

Interesting to hear - thanks!

The light fittings if loose sometimes contribute to the vibration - had 214 in multiple with 216 - 214 not the best I've had - loose light fitting causing a rattling and don't know whether something up with the engine/gearbox, as weird sound/performance at times at low speeds. 336 later had a rather noisy wheelflat (only other annoyance of the 172s is the sound of a wheelflat!).