Voyager Electrical Hum on Braking Only

[trainJam]

Correct me if I'm wrong: Voyagers have diesel engines to power electric motors.

What causes the buzzing sound on braking but not acceleration?

On regular electric trains, I don't hear this - or if there are sounds, then they are usually heard both in acceleration (and braking on a lot of trains).

 

[hexagon789]

What causes the buzzing sound on braking but not acceleration?

Continously to a low speed or immediately but, only briefly, a brake application is made?

The former - I'd suggest the rheostatic braking operating.

The latter - I'd suggest the actual electric signal for a brake demand being sent, some Sprinters make a similar, brief, sort of 'chirp' noise when a brake application is made, you hear the noise and then feel the brakes apply.

 

[AM9]

Continously to a low speed or immediately but, only briefly, a brake application is made?

The former - I'd suggest the rheostatic braking operating.

The latter - I'd suggest the actual electric signal for a brake demand being sent, some Sprinters make a similar, brief, sort of 'chirp' noise when a brake application is made, you hear the noise and then feel the brakes apply.

Would that be inrush through the brake valve on the air line?

 

[hexagon789]

Would that be inrush through the brake valve on the air line?

Possibly, having thought more about it I'd describe the sound as almost like a shrill electric whistle, so it could well be exactly that which you describe.

 

[coppercapped]

So it’s nothing to with the rheostatic brakes then?

 

[voyagerdude220]

I think there are possibly two different noises which Voyagers make when braking:

You've got the initial high pitched noise which lasts 2-3 seconds which you can hear much more clearly when you're in the vestibule by a toilet/exterior door. Happens when the Driver initially applies the brakes. You can often hear this immediately after the train has come to a stand at a Station as the brakes are fully applied and the Driver releases the doors.

You've also got the continuous high pitched "humming" noise which I think from memory was more prevalent when you're sat in the carriages themselves- which I'm guessing is the rheostatic brake noise which Hexagon789 and Coppercapped are referring to.

 

[Halish Railway]

It’d be rheostatic breaking, it’s a noise that is faintly present on Class 80Xs when running on diesel and all models of Hitachi AT300 when the return to the overhead wires has been isolated.