Class 37 number of notches? - (answered)

[Hamburger]

Hello,

I wonder how many notches the throttle of the Class 37 might have, or is it without 'steps"?

I listened to several DCC sound projects, some have just three, some more.

Bit confused - may anyone can help?

Thanks

Wolf

Edited May 15, 2019 by Hamburger

[hexagon789]

44 minutes ago, Hamburger said:

Hello,

I wonder how many notches the throttle of the Class 37 might have, or is it without 'steps"?

I listened to several DCC sound projects, some have just three, some more.

Bit confused - may anyone can help?

Thanks

Wolf

 

Technically notchless. There is an initial 'notch' (roughly 10% power), then it's fully variable up to full power.

[Hamburger]

Thanks , that helps me alot.

[standardblue]

Isn't there a number of set engine speeds?

 

Mark

[roythebus]

No, the power handle sends air to the engine governor. That air pressure varies as the driver moves the handle. The engine speed varies depending how much air pressure there is in the governor to put it in simple terms. Electric trains have notches.

Edited May 15, 2019 by roythebus

[Davexoc]

1 hour ago, standardblue said:

Isn't there a number of set engine speeds?

Basically notch on is a a low air pressure onto the governor to take up the slack, much like initial on the brake controller puts around 10 psi in the brake cylinders to get the blocks in contact with the wheels.

Both then are variable/proportional to how much more you pull on the handle until you reach maximum pressure.

Notches as on IC125 are a series of pressures that increase by operating solenoid valves in different combinations to give speed/brake steps.

 

Dave

[royaloak]

Just for clarity it is power notches and brake steps.

[woodyfox]

Power was varied via a load regulator. Any power steps on the recording would be the various phases of power governed by the regulator. 

 

[Classsix T]

As a connected aside, do the better sound files replicate the change in engine note as the field diverts kick-in, or is that what the OP is hearing, though more than two seems excessive?

 

C6T. 

[russ p]

Is it possible to replicate field divers automatically with DCC sound?

Incidentally the accelerator valve which is valve at the base of the power controller on a 37 which sends regulating air to the governor is the same internally as a Davis and Metcalf straight air brake valve 

[45125]

Depending how the governor is set up all sorts of things can be heard when power is taken. A small amount of reg air is fed to the governor to aide the governor, but no speed increase happens, just a bit more fuel. At around 7 psi the load reg will move off and the engine note should change as excitation increases, with more fuel how ever no engine speed should occur at around 15 psi of reg air the load reg will be at max but the engine speed should not occur this is what is know as max load min speed. As more air is applied to the governor the speed will increase and the load regulator will start to back off. If this not set right and no speed increase takes place the engine will sound like it is struggling (Crewe set some power units up that didn't increase the rev until above 20 psi of reg  air) . Engine will increase to max as the reg air gets to 45psi, the air pressure actually goes to 50 psi so as over come minor air leaks in the system.

The reg air valve at the base of the controller was made by Clayton Dewandre and is much smaller than a D&M straight air brake valve. The cam on the controller which operates the valve can be adjusted either on a spline or if really out by a bit of hand filling.

[Classsix T]

 I remember attending a NYMR diesel Gala and 40145s diverts were noticeably more apparent than D200's. Perhaps not surprisingly. 

I subsequently learned the mph at which diverts kick-in. For good or bad, istr generator EE traction was first divert at 27mph? Which is a rather telling overspeed at light railways! 

Alternator fitted traction works differently of course. On a 56 the first divert kick-in is at summat like 37mph?

 

C6T