Gday Dudley, All

33" wheels were used because the early motors were big, WH 225 50 HP
are a good example compared with later motors of the same power which
had a fan on the armature and could get rid of heat better such as the
GE 247 40 HP and similar WH and DK motors. GE 201 50 HP fan

These motors allowed 24" wheels,26" more common which reduced the floor height and with drop ends and centers got rid of an extra step.

Many Aussie trams till the plastic trams came in are like this

The PCC with 24" wheels were the 1st to really lower the floor.

Cheers, Mick

On 22/09/2017 1:16 AM, 'Dudley'transitconsult@... [TramsDownUnder] wrote:
>

>

> ISTR that the standard BR wheel diameter was 4’ for coaching stock = 48”. I think that the biggest tram wheel was 38”, but more definitely 33” in Melbourne. However, I have just found the drawings for the LCC E3 cars, and the driving wheels were 31 and 7/8” dia, with Pony Wheels 21 and 7/8” dia. 74 seats in a length of 33’ 10”.

>

> Tram wheels were kept smaller than HR wheels as otherwise passengers would have a problem in boarding and alighting. There was already one large step up to the folding step, then a small step to the cab deck and then another small step to the saloon deck.

>

> Track grooves were always kept as small as possible so as to reduce the problem of cart getting stuck in the grooves – remember they had thin wheels strapped in iron, and that was not far off the width of the groove. Also narrow grooves reduced hunting, and led to reduced wear and fewer derailments.

>

> I can’t remember if London adopted flange running at crossings, but I would have thought that was normal practice. At least one town adopted wheels with a central flange, and used track with two parallel rails closely spaced. This was reported to give very good running over crossings – don’t know if the extra rail was continuous or only at and near frogs.

>

> You will remember from the books on Sydney tramways that when the cars were transferred over the railway system from N to S and vv, the main line was shut down, I think staff had to put in fillers at all frogs.

>

> Regards

>

> Dudley

>

>