Non-steam railway stuff / Deltics [merged]

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Re: Diesel Deltics

Postby MOD » Sun Jun 12, 2011 2:44 pm

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Re: Diesel Deltics

Postby RLN » Sun Jun 12, 2011 3:57 pm

Like this




Like the sound of the local diesel at the start of this clip.


It will start.
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Re: Non-steam railway stuff [merged]

Postby Mayfly » Sun Jun 12, 2011 4:07 pm

Topic Merged so all Deltic stuff is in the same place
In memory of a very dear friend - Mike Pearson

Very fond memories of Robbie Gilvary - DTs 1st Vulcan Captain who taught DT all he knew.
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Re: Diesel Deltics

Postby 10680 » Mon Jun 13, 2011 9:58 am

RLN wrote:Deltics are great.


I saw the Deltic, hired for the Aluminium factory run, up in the wilds of Scotland last week. Will post a picure later.
I'd rather be skiing
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Re: Non-steam railway stuff / Deltics [merged]

Postby MOD » Mon Jun 13, 2011 8:05 pm

Why were the Deltics so difficult to 'Cold Start'?

At 2.37 ( in RLN's last vid ) you also see a belch of raw flame in the exhaust..

Dodgy 'Glow' Plugs!!! =))

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Re: Non-steam railway stuff / Deltics [merged]

Postby RLN » Mon Jun 13, 2011 8:37 pm

I don't think they had preheat. As they were 2 stroke, they used a lot of oil, hence the white smoke and the oil is probably the cause of the flames in that clip. I believe they used the generator as the battery to turn it over, and had to press the starter until it fired. They were also prone to exhaust fires.
The naval version used a cartridge start into one of the cylinders with five cartridges in a rack, although it usually started first time.
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Re: Non-steam railway stuff / Deltics [merged]

Postby Hydealfred » Mon Jul 25, 2011 7:20 pm

You are right RLN - in diesel electrics the generator does act as the starter under battery power. It just keeps spinning until the engine fires. It has always struck me as odd why hydraulic transmission was not used more within the diesels of the late 50's - 60's. With generators there is always the danger of a flashover which has sidelined many a diesel. With hydraulics you dont get this. Am I right in thinking that many of the modern diesel units use hydraulic transmission ?

Many happy days I have had watching the Westerns coming round the Sea Wall at Teignmouth. I also remember the Deltics when they were running up through York. Very pleasing that some survived into preservation.
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Re: Non-steam railway stuff / Deltics [merged]

Postby RLN » Mon Jul 25, 2011 7:29 pm

The following is an excerpt from Wiki - it mentions how they overcame flashover. The full article is

http://en.wikipedia.org/wiki/Diesel_locomotive

A diesel-mechanical locomotive uses a mechanical transmission in a fashion similar to that employed in most road vehicles. This type of transmission is generally limited to low-powered, low speed shunting (switching) locomotives, lightweight multiple units and self-propelled railcars.
Schematic illustration of a diesel mechanical locomotive

The mechanical transmissions used for railroad propulsion are generally more complex and much more robust than road versions. There is usually a fluid coupling interposed between the engine and gearbox, and the gearbox is often of the epicyclic (planetary) type to permit shifting while under load. Various systems have been devised to minimise the break in transmission during gear changing, e.g. the S.S.S. (synchro-self-shifting) gearbox used by Hudswell Clarke.

Diesel-mechanical propulsion is limited by the difficulty of building a reasonably sized transmission capable of coping with the power and torque required to move a heavy train. A number of attempts to use Diesel-mechanical propulsion in high power applications have been made (e.g. the 1,500 kW (2000 horsepower) British Rail 10100 locomotive), although none have proved successful in the end.
Diesel-electric

For locomotives powered by both external electricity and diesel fuel, see electro-diesel below. For locomotives powered by a combination of diesel or fuel cells and batteries or ultracapacitors, see hybrid locomotive.



In a Diesel-electric locomotive, the Diesel engine drives an electrical generator whose output provides power to the traction motors. There is no mechanical connection between the engine and the wheels. The important components of Diesel-electric propulsion are the Diesel engine (also known as the prime mover), the main generator, traction motors and a control system consisting of the engine governor as well as electrical and/or electronic components used to control or modify the electrical supply to the traction motors, including switchgear, rectifiers and other components. In the most elementary case, the generator may be directly connected to the motors with only very simple switchgear.


Originally, the traction motors and generator were DC machines. Following the development of high-capacity silicon rectifiers in the 1960s, the DC generator was replaced by an alternator using a diode bridge to convert its output to DC. This advance greatly improved locomotive reliability and decreased generator maintenance costs by elimination of the commutator and brushes in the generator. Elimination of the brushes and commutator, in turn, disposed of the possibility of a particularly destructive type of event referred to as a flashover, which could result in immediate generator failure and, in some cases, start an engine room fire.

More recently, the development of high-power variable-frequency/variable-voltage (VVVF) drives, or "traction inverters," has allowed the use of polyphase AC traction motors, thus also eliminating the motor commutator and brushes. The result is a more efficient and reliable drive that requires relatively little maintenance and is better able to cope with overload conditions that often destroyed the older types of motors.
Engineer's controls in a Diesel-electric locomotive cab. The lever near bottom-centre is the throttle and the lever visible at bottom left is the automatic brake valve control.
Diesel-electric control
MLW model S-3 produced in 1957 for the CPR adhering to designs by ALCO.

A Diesel-electric locomotive's power output is independent of road speed, as long as the unit’s generator current and voltage limits are not exceeded. Therefore, the unit's ability to develop tractive effort (also referred to as drawbar pull or tractive force, which is what actually propels the train) will tend to inversely vary with speed within these limits. (See power curve below). Maintaining acceptable operating parameters was one of the principal design considerations that had to be solved in early Diesel-electric locomotive development and, ultimately, led to the complex control systems in place on modern units.
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