Re: Re: Track brakes

Thanks, Greg. Good idea having them on the dead man. It's asking a bit much
for the disc brakes to pull a tram down from normal operating speeds.

Bob Murphy
----- Original Message -----
From: "Greg King" <[email protected]>
To: <[email protected]>
Sent: Tuesday, December 11, 2001 9:05 AM
Subject: Re: [TramsDownUnder] Re: Track brakes

Hi Bob,

On the Z,A and now W, the track brakes are purely for emergency and it's a
case of "all on or nothing" you really can't graduate them. The B's are
slightly different, you can vary them a bit and all the bells and whistle
sound when you use them (which can be a pain at times). The other cars,

when

you lift your foot from the (politcally correct) safety pedal, the track
brakes drops, on the B's, it will bring you to a firm service stop.

Greg

Hi Peter.

A lot of people think that magnetic track brakes are necessarily rough.

Not so.

Most of them think that because most trams are set up so that you have

to

be

using a lot of brake pedal for them to come on.

In San Francisco we had 70 1100 series trams (ex-St Louis 1700s. You saw
that wonderful model of Greg's. One of them.) that had a dash switch

which

you could use independent of the dynamic brakes. The switch was

variable,

the harder you pressed the more track brake you got.

That independent control was good on night runs in the fog where we were
going up and down steep grades. You could use the track brakes and just
"spot" the car with the dynamics. That way you didn't get flat wheels.

Our

sanders were stuffed so that was the best way. Of course that is hard on

the

track. It wears the head down. It's a bit like sanding it.

But it taught me that track brakes are not rough per se. They never come

on

(or shouldn't) for a normal service stop. They are there for emergencies
when you jam the brake pedal to the floor.

On the Muni Railway 1100s, if you went to the floor on the brake pedal,

the

sander came on, the repeater gong sounded, the track brake came on and

the

doors went into kind of a neutral so you could pull them open if you had

to.

I don't know what the Z, A and B class cars do.

Cheers,

Bob Murphy

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