Chiltern class 172 - Change to hydraulics transmission?

[Bletchleyite]

The other downside of electric drive is that traditionally it wasn't very efficient - there's a reason you don't have it in your car!

You don't have it in your car because it's expensive and complicated and takes up a lot of space.

Of course, series hybrids do, and those will become more common.

 

[Billy A]

You don't have it in your car because it's expensive and complicated and takes up a lot of space.

Of course, series hybrids do, and those will become more common.

That as well, but the early manifestations of electric drive with DC motors were fairly dire from the efficiency point of view. I think they've got it up to 90% or so nowadays which is something closer to what you'd get with a torque converter automatic box. Interestingly hybrids use mechanical drive at least some of the time.

 

[apinnard]

Do we know why the 220s are so much faster than other units? They have the same engine as both the 180 and 185, and yet both of those are a fair amount slower (although they have hydraulic transmissions as opposed to electric motors and generators).

Eversholt did a test in the early days of the 222's. I can't remember how many cars they used, but they disabled half the engines and sent it out from Etches Park southbound and it still beat HST timings.

 

[Bletchleyite]

Interestingly hybrids use mechanical drive at least some of the time.

I think that will reduce over time, though.

 

[Prestige15]

Always interesting to read, and where I get much if my acceleration times info from. It does show how superior 172s are off the mark compared to a 168/170 etc.

Can the 168/170 be fitted with FLEXX-ECO bogies?

 

[t_star2001uk]

Can the 168/170 be fitted with FLEXX-ECO bogies?

With some modifications, yes, its possible.

 

[hexagon789]

Can the 168/170 be fitted with FLEXX-ECO bogies?

Presumably to save weight? While possible I'm not sure if it's worthwhile as such.

 

[delticdave]

Strictly speaking, the Voith box is a three speed unit with two gears - first speed involves a torque converter driving low gear while second speed uses a fluid coupling to drive the same gear with less slip. It drains all the couplings when power is cut so it'll coast in neutral - it doesn't coast in gear as such.
Yes, Voith make a conventional "mechanical" box - the Diwarail, a modified version of their four speed bus gearbox

The SCG box was a bit of a disaster from the reliability point of view..

I can't quite see why you can describe the Voith transmission as a 3-speed.
I've owned a Ford Escort with a 3-speed auto & the torque-converter would slip in each ratio but above certain RPMs it would "lock-up" in 3rd, so it felt like a 4-speed with 3 discernable shifts, but still only 3 gear ratios.
A later (Vauxhall) car with a 4-speed Asian Warner box would lock-up in 3rd & 4th, but still only 4 ratios.....

Most modern multi-ratio automatics (bus, car, train) still use a fluid coupling but only when starting in 1st gear & to smooth the shifts.

 

[Billy A]

I can't quite see why you can describe the Voith transmission as a 3-speed.
I've owned a Ford Escort with a 3-speed auto & the torque-converter would slip in each ratio but above certain RPMs it would "lock-up" in 3rd, so it felt like a 4-speed with 3 discernable shifts, but still only 3 gear ratios.
A later (Vauxhall) car with a 4-speed Asian Warner box would lock-up in 3rd & 4th, but still only 4 ratios.....

Most modern multi-ratio automatics (bus, car, train) still use a fluid coupling but only when starting in 1st gear & to smooth the shifts.

The Voith has two gears, but I think that the company describe it as a three speed, even though it's really "three" speed. The change (or "change") from first to second is the replacement of a torque converter by a fluid coupling, but there's still a significant reduction in engine speed. It's more than the locking of a torque converter.
Are you sure about your Escort? I had a three speed one many years ago, but it had a torque split system. First gear was hydraulic, second was partly mechanical and third was almost entirely mechanical with the converter being bypassed rather than locked - you could feel the slip disappearing as third engaged. It was the later four speed that had a locking converter.

 

[delticdave]

The Voith has two gears, but I think that the company describe it as a three speed, even though it's really "three" speed. The change (or "change") from first to second is the replacement of a torque converter by a fluid coupling, but there's still a significant reduction in engine speed. It's more than the locking of a torque converter.
Are you sure about your Escort? I had a three speed one many years ago, but it had a torque split system. First gear was hydraulic, second was partly mechanical and third was almost entirely mechanical with the converter being bypassed rather than locked - you could feel the slip disappearing as third engaged. It was the later four speed that had a locking converter.

My '89 (Front Wheel Drive) Escort used the Ford ATX transaxle, which is described as a 3-speed with lock-up only in 3rd gear.
The torque converter isn't "by-passed", it just locks the impeller & turbine shafts, in 3rd on the Ford but 3rd & 4th on the Vauxhall.
AFAIK, the modern 8 & 9 speed car transmissions allow torque converter slip only in 1st, as per the more modern bus 'boxes, all in the name of efficiency / & cleaner emissions.

As for the Voith transmission, it allows slip in 1st gear all the way to the point when the DMU has reached the maximum speed in 1st, the rpms then drop, it shifts into 2nd gear, locks-up & the train continues to the maximum possible speed.
Said maximum speed varies from train to train, due to differing final-drive ratios, engine power/ maximum allowed rpm's & gradients.

 

[Billy A]

My '89 (Front Wheel Drive) Escort used the Ford ATX transaxle, which is described as a 3-speed with lock-up only in 3rd gear.
The torque converter isn't "by-passed", it just locks the impeller & turbine shafts, in 3rd on the Ford but 3rd & 4th on the Vauxhall.
AFAIK, the modern 8 & 9 speed car transmissions allow torque converter slip only in 1st, as per the more modern bus 'boxes, all in the name of efficiency / & cleaner emissions.

As for the Voith transmission, it allows slip in 1st gear all the way to the point when the DMU has reached the maximum speed in 1st, the rpms then drop, it shifts into 2nd gear, locks-up & the train continues to the maximum possible speed.The
Said maximum speed varies from train to train, due to differing final-drive ratios, engine power/ maximum allowed rpm's & gradients.

My 1984 Escort with the ATX box definitely had a torque split system - you could feel it working - so I've asked Mr Google and came up with this: http://www.carkipedia.com/automatic_transmissions_and_transaxles/ford_atx_transaxle.php In short there were three different variations. The description is applicable to American models, but nonetheless the third paragraph describes my Escort. It worked just fine, as I recall.
The Voith gearbox never literally locks up but slip in fluid coupling mode (or modes in the three "speed" models) is greatly reduced as compared to torque converter mode. As originally designed Voith used one gear, one torque converter and one fluid coupling, but the more recent models have added a high gear with its own fluid coupling so the 312 unit (to take an example) has torque rating 3, one torque converter and two couplings. A 311 would have capacity 3, one torque converter and one coupling. I occasionally travel in DMUs that have two distinct "gearchanges" at 40 and 70 kmh so the first of these is switching from converter to coupling, still in low gear, and then it switches to high gear and its associated coupling.

 

[grumpyoldman01]

Can the 168/170 be fitted with FLEXX-ECO bogies?

Wouldn't the fitting of FLEXX-ECO bogies to class 168s cause problems for Chiltern in the short-term? As I understand it, trip-cocks can't be fitted to inside framed bogies, and consequently 172s can't run on their own or as leading sets when coupled with 168s on the electrified part of the Met&GC Joint.

 

[hexagon789]

Wouldn't the fitting of FLEXX-ECO bogies to class 168s cause problems for Chiltern in the short-term? As I understand it, trip-cocks can't be fitted to inside framed bogies, and consequently 172s can't run on their own or as leading sets when coupled with 168s on the electrified part of the Met&GC Joint.

I believe that's correct, yes. 172s have to be 'boxed-in' by tripcock-fitted units if going up that way - which must be pretty rare.