starting a dead DMU

[Ken H]

So to summarise:-
you cant start a train because none had/have mechanical transmissions - even 1st gen DMU. I have never owned any car other than a manual so excuse my ignorance!.
You can jump start but using jump leads or a battery booster thing but that is a fitter job, not train crew.
I assume this is true of diesel electric locomotives, and the diesel hydraulics like hymeks and cl 52

Maybe you could have bump started the Fell!

 

[TRAX]

Didn’t some first-gen DMUs have manual gearboxes ?

 

[Ken H]

This is a class 101 DMU drivers position. I think many 1st gen DMU that survived long had a similar layout
The big grey handle on the left if the throttle
The knob behind was wipers
2 dials is revs is speedo and revs. The rev counter had marks on when to change gear
The big chrome button atop a grey thing is AWS acknowledgement.
Red button is buzzer to communicate with the guard
The right grey handle with black knob is the gear change. The driver brought with him a brass handle that slotted into the groove under the handle. To get the handle out the unit had to be in neutral.
The big dome with holes in it is the brake valve. Again, the driver brought the handle with him.
By the windscreen is the AWS indicator and brake pressure valves. Below the brake valve there is an ashtray.
Out of shot to right is an emergency brake handle and a handbrake
Engine start/stop buttons on panel to left.

I assume this unit had some sort of hydraulic gearbox.

 

[TRAX]

Not hydraulic, mechanical (epicyclic).

 

[Ken H]

Not hydraulic, mechanical (epicyclic).

er?
could someone explain that, please?
And to get back on topic, can you bump it?

 

[TRAX]

Internet will have good explanations of what it is.
Unless there is a manual clutch on the 101, no you can’t bump it.

 

[rebmcr]

Only the running engine will provide electricity via the alternator on a car with a dead battery.

Am I correct in recalling that the opposite is true on some loco-hauled carriages, which have an alternator attached to the wheelsets?

 

[TRAX]

This is possible, to provide electricity to the carriages with mechanical energy coming from rotating wheelsets. It’s the same principle, converting mechanical energy into electrical energy via an alternator.
But this time there is no engine or motor involved, and in both cases the alternator doesn’t power an engine or motor.

 

[Ken H]

Am I correct in recalling that the opposite is true on some loco-hauled carriages, which have an alternator attached to the wheelsets?

Mk 1's had a dynamo, not an alternator. (2)
It was driven by a belt from the wheelsets, a bit like a fanbelt on your car.
It provided low voltage DC for battery charging and carriage lights. This is before ETH so no high voltage feed to the coaches.

The RCH jumpers provided control of train lights meaning it was possible to turn on/off all the lights on a train. But I dont think they carried actual lighting current.
They later had public address and push pull(1) signals added to their workload.

(1) this was time division multiplex signals sent down the train from a driving trailer to a locomotive. First used between the Mk2 DBSO and the Cl 47/7 locos on the Edinburgh-Glasgow push pulls, then generally used elsewhere.
(2) A dynamo makes DC current, an alternator AC. A car alternator has a built in rectifier that converts the AC to DC.

 

[chuff chuff]

Ah the good old days,this one has the new fangled engine and air and axle lights.Do I miss them no I do not.

 

[Ken H]

Ah the good old days,this one has the new fangled engine and air and axle lights.Do I miss them no I do not.

I used to love sitting behind the driver. especially one with a grudge between Leeds and York

 

[Highlandspring]

er?
could someone explain that, please?
And to get back on topic, can you bump it?

As explained in several posts on this thread now, you can’t bump start a 1st generation DMU. An epicyclic gearbox is quite complicated and uses a planetary gear system. The various gears in the box (the planet gears) rotate around a geared ring to turn another gear at the centre (the sun gear). Each ratio has a particular planetary gear set - four in a 1st gen DMU - each of which is selected by tightening a brake band round the geared ring to stop it, causing the sun gear to rotate through the action of the planets and thus drive the wheels through a particular speed range. It makes far more sense once you see it in operation so perhaps googling “epicyclic gear box” would help.

A 1st generation DMU doesn’t have a clutch as it uses a fluid flywheel between the engine and the gearbox instead. The rotation of the engine crankshaft causes the oil in the fluid flywheel to move through centrifugal force and this turns the output side which is connected through the freewheel to the gearbox. The fluid flywheel acts like an automatic clutch. There’s no way of getting the rotation of the rail wheels back through the gearbox, freewheel and fluid flywheel into the engine to turn the crankshaft without causing catastrophic damage, which is why you can’t do a bump start.

There were some old shunters fitted with clutches and direct mechanical gearboxes like road vehicles and in theory they sould be bump-startable in the usual way.

 

[Ken H]

As explained in several posts on this thread now, you can’t bump start a 1st generation DMU. An epicyclic gearbox is quite complicated and uses a planetary gear system. The various gears in the box (the planet gears) rotate around a geared ring to turn another gear at the centre (the sun gear). Each ratio has a particular planetary gear set - four in a 1st gen DMU - each of which is selected by tightening a brake band round the geared ring to stop it, causing the sun gear to rotate through the action of the planets and thus drive the wheels through a particular speed range. It makes far more sense once you see it in operation so perhaps googling “epicyclic gear box” would help.

A 1st generation DMU doesn’t have a clutch as it uses a fluid flywheel between the engine and the gearbox instead. The rotation of the engine crankshaft causes the oil in the fluid flywheel to move through centrifugal force and this turns the output side which is connected through the freewheel to the gearbox. The fluid flywheel acts like an automatic clutch. There’s no way of getting the rotation of the rail wheels back through the gearbox, freewheel and fluid flywheel into the engine to turn the crankshaft without causing catastrophic damage, which is why you can’t do a bump start.

There were some old shunters fitted with clutches and direct mechanical gearboxes like road vehicles and in theory they sould be bump-startable in the usual way.

Thanks.

 

[KevinTurvey]

For anyone interested and not seen this already, this is part two of a four part fascinating BTF film on how dmu's work and how to drive one, including a detailed look at the gearboxes and transmission from about 9m30s.

 

[edwin_m]

Many years back I recall reading that British Rail had called out the AA at least once to jump-start a locomotive.

 

[johnr57]

For anyone interested and not seen this already, this is part two of a four part fascinating BTF film on how dmu's work and how to drive one, including a detailed look at the gearboxes and transmission from about 9m30s.

thank you - need a "like" button!

 

[big all]

Many years back I recall reading that British Rail had called out the AA at least once to jump-start a locomotive.

would read that with scepticism as locos are usually between 90-110v battery for starting and lights etc
may be a van or other road based vehicle

 

[Jensen]

That story about the AA may relate to the tale that an AA Patrolman reported a "dead" APT on the WCML in Cumbria that he saw when passing over the railway.

 

[big all]

That story about the AA may relate to the tale that an AA Patrolman reported a "dead" APT on the WCML in Cumbria that he saw when passing over the railway.

aaahh a pppp take

 

[big all]

there used to be a driver at redhill with a part share in a racehorse and the name was influenced by a dmmu so you might expect some deep and meaning full connection

ehhh no it was named after the electric fan heater fitted in the cabs later in life
if you look at the switches they had a "full" top position an "off" central position and a"half so it was called "full of ale"
dont think it performed very well