Top speed of a Class 150?

Why do you think they called them Sprinters?

Fred X

Cos reality with words such as uncomfortable, ugly, cramped and noisy might have put some passengers off.

Cheers, Simon

I understand they were fitted with what was called " Twin Disc 'hot shift' gearboxes " which accounted for the 'uncomfortable' & 'noisy'. The heatshield may be for the air con on the roof. Top speed ? About 75 mph ugly ? Hove you ever seen the Skoda built versions of the 150 ?

Prototypes tested in Derby and Matlock

Chris

"Dragon Heart" wrote

I was going to query this, but checked before I did and can confirm that

75mph is indeed the claimed top speed. Seems very low for a second generation dmu.

John.

141-144 and 150, 151, 155 and 156 were designed for a 75mph maximum speed but with rapid acceleration up to that speed. 158 was able to go up to 90 mph as using disc instead of tread brakes gave it the same stopping distance from 90 as "conventional stock" (IIRC that was the phrase used) needed from 75 mph. The choice of a 75mph limit for 150 et al was really imposed by signal-sighting distances on the lines they were expected to be used on and the limits of tread brakes. The speed only seems low now because we've all got used to the performance of 158s (and later units) and forget just what a breakthrough in performance they were.

101s could go 75mph.

Eventually...

I've seen 90 on the speedo of a Swindon 120 with the rev counter in the red. And it was a lively trip.

I was sitting behind the driver - I miss that about the newer DMUs

Many moons ago I travelled regularly from Stockport to Westbury. During a "work to rule" the diesel that took over from New Street to Bristol was unavailable, so the train was replaced by a 9 car DMU (3 x 3). Expecting a very slow trip, we actually lost very little time (10, 20 mins or something) - the unit took some winding up but didn't half go when given some welly!

Much later I was on a delayed unit from Reading to Paddinton travelling on the cushions with my driver and commented to him that the unit driver was giving it some welly. "Isn't he just" came from the next row of seats - from a Traction Inspector, who set off forward for a little chat. I'd assumed that units had semi-automatic clutch tied into a speed limiter determining where gear changes should happen, but my driver explained that you can actually delay the change if you like, but it's a Bad Thing, and the gain is not as good as it sounds (like driving a diesel car).

Cheers Richard

Before the days of data recorders and radar speed traps, it was not uncommon for Class 156 to reach the mid -eighties at some locations, and I have heard of Class 150 reaching similar speeds. First generation dmu's were mostly liimted to 70 mph, and some (**) struggled even to reach that limit . (**) The exception was units with all cars powered, which had pretty good acceleration.

Bevan Price

Few weeks ago found web site set up by ex BREL employee. Good photo's of the prototypes etc. but can I find it again ........

I remember it being 75 mph as I thought myself it was a little slow, more like 85 to 90, but he was the chap who set up & carried out the maintenance schedules apparently,

Chris

You mean this one?

Fred X

It's got some good stuff but what a horribly designed site: yellow text on a background of lit up carriages makes it so hard to read.

=A0

Well done that man

" ..... a horribly designed site .... " ? I have seen a lot worse ! How about navy blue text on a black background !

Chris

Chatting with a driver - gear changes take about 7 seconds 3 off power change wait 4 then go - or 4 then 3 anyway it was a 7 second change.

Go on a few years and returning from a car delivery a DMU was being thrashed - gear change - just move the gear lever to the next gear!

That driver was power shifting it! Apart from autos I haven't been near powershifting since my first bike when I accidentally knocked from 3rd to

4th at full RPM full throttle and it changed up OK.

My memory of early DMUs was that the tachometer had two marks. When the needle reached the upper mark, the driver would cut power; when it fell to the lower mark he would shift up a gear, wait a bit then reapply power. I suppose that took in the order of 7 seconds. If a downshift was required, I guess there was a similar procedure.

kim wrote:

Sounds like you are talking about the Pacers of class 142-144. They all all use hydraulic transmission and so not have any heating units on the roof. Top speed for 150-156 is 75 MPH as their eventual cascade location was urban (150) and rural/urban (155, 156) where locations for above 75 MPH running are rare and higher acceleration between frequent stops is more desirable.

What you say is correct for the Pacers which are in essence a bus body on a long wheelbase 4 wheel wagon. There was so many problems with the gearboxes that they had to be replaced with the hydraulic drive used on the sprinters.

Chris