Hey Mick,

Who knows now why some GE247 motors were faster than others? But something to do with current in either armatures or field coils must have been different. I don’t think Preston ever ventured into roller bearings in motors.

Regards,

Richard

On 12 Dec 2018, at 7:42 pm, Mick Duncan kitbuny@...> wrote:

Gday Richard

Agreed about W peformance

I doubt that Preston would have used different thickness wires
or alter the No of turns.

However if the fields were on thicker insulating pads,the air gap
would be smaller and thus the flux stronger and the motor more
powerful,or less powerful if the pads were thinner

This might be the reason for different peformances for the same
motors and wheel dia

436 at Kew, a SW2 and about 18 tons was a real flyer,better than
most Big Cars.247s and 28" wheels,whereas some W2s were real slugs,
lucky to get to 25MPH and crawled up hills

Cheers, Mick

> On 9/12/2018 10:39 PM, 'Richard Youl' via TramsDownUnder wrote:

> Hi Mick,

>

> It may have been 767, an unremarkable tram re performance.

>

> Unlike modern trams which all essentially behave the same as others in its class, Ws varied a lot from one to the next re speed.

>

> While worn or new wheels would make a difference, I think there was more to it than just the wheels.

>

> Preston rewound the motors for many years and I have sometimes wondered if standards varied over the years, including the thickness of the wire and the number of turns of wire on each coil, both field coils and armature coils.

>

> It’s a pity we did not then have the GPS measuring equipment available today to know just how fast those Ws could go. But all modern trams are faster.

>

> Richard

>